[Sursound] ambisonic microphone techniques

[Chris Caudle]

I have several questions on Ambisonic microphone techniques that I have
not so far been able to find concise answers to.
This may get a bit rambling, but I'll try to break the question(s) into
logically distinct parts. Anyone who replies please feel free to change
the subject line to represent the specific topic, since some of the
sub-questions are really completely separate issues.

1) Is anyone doing direct B format recording, meaning using two
figure-of-eight microphones in a M-S arrangement with an added omni
for the W signal?
I am told that some of the gorgeous Chesky recordings were done with
an AKG C-24 dual capsule microphone. I don't know if they were done
with capsule angles of 45/45, or 0/90deg., but either way I think that
anyone would be hard pressed to argue that you cannot get very good
sound with condenser figure-8 capsules. The C24 is discontiuued, but
AKG make a newer model with dual capsules.
Josephson even makes a microphone with two selectable
pattern capsules plus an omni capsule in the same housing, so the
technique could be used even without resorting to cumbersome multiple
microphone mounting arrangements like Nimbus seemed to use.
So why do all the ambisonic recordists seem to use the Soundfield?

2) What effect do non-coincident microphones have on ambisonic
recording?
The Soundfield microphone has the capsules as nearly coincident as
possible,
and the ambisonic papers I have been able to read seem to assume
coincident
capsules as the starting point for the mathematical derivations, yet Dr.
Moorer of Sonic Solutions and Jack Vad of the San Francisco Symphony
have
done experimental recordings which utilize what is basically the NOS
technique (hypercardioid microphones at 110deg. and 13cm to 17cm
separation) with an additional rear facing hypercardioid, from which
the horizontal ambisonic signals were derived.
The paper can be found at:
http://www.sonic.com/pdf/wp_aud_RationalBasis.pdf
That paper is the first mention I have seen in print of non-coincident
ambisonic techniques (although admittedly I do not have a lot of
reference material which covers ambisonics in any detail).

3) Using the the technique described by Dr. Moorer, is any advantage
gained
by using more than three microphones to generate the ambisonic signals?
I think that would in effect be similar to mathematically having three
unknowns but more than three equations constraining the results, i.e.
the
system is overspecified so you have some redundancy of information. In
practice it might have some benefit because you rely on the off-axis
performance of each microphone less, or it may have some disadvantage
because
you have more leakage between microphones, with the resultant phase
cancellation problems.
I am much too rusty on my matrix math to fully follow how Dr. Moorer's
equations could be extended to using four or five microphones. Does
anyone
have a reasonably educated guess as to whether the microphone technique
being developed by Jim Johnston at AT&T research labs is likely using
the
same idea? That array is described as 5 hypercardioid microphones, with
an
angular separation of 72 degrees between each, with two shotgun
microphones
pointed up and down. The array of 5 microphones separates the capsules
by
approximately "the diameter of a human head."
You can see a picture of JJ's array at:
http://www.stereophile.com/showarchives.cgi?465:4
and at:
http://www.stereophile.com/shownews.cgi?1035


-- Chris Caudle

[John A. Leonard]

Post by Chris Caudle
So why do all the ambisonic recordists seem to use the Soundfield?

Because it works, is quick and easy to set up, has a well-documented history
and excellent back-up from the company. My ST250 has a Rycote suspension
mount and windshield and I mostly use it for location recording of effects
and music where time and repeatability are of the essence.

I don't have the luxury of a lab or a controlled environment for my
recordings, they're part of how I make my living, so I need to have
practical tools that are usable in all sorts of situations.

YMMV, but that's my $0.02 worth

Regards,
--
John A Leonard
Aura Sound Design Ltd.
23 Charlotte Road
London EC2A 3PB
Tel: [phone] Fax: [phone]
http://www.aurasound.co.uk

The book is out!
http://www.aurasound.co.uk/files/theatresound.html

[G***@aol.com]

John,

I agree. We're up to $0.04 worth.

-- Gary Reece

Post by Chris Caudle
So why do all the ambisonic recordists seem to use the Soundfield?

Because it works, is quick and easy to set up, has a well-documented history
and excellent back-up from the company. My ST250 has a Rycote suspension
mount and windshield and I mostly use it for location recording of effects
and music where time and repeatability are of the essence.

I don't have the luxury of a lab or a controlled environment for my
recordings, they're part of how I make my living, so I need to have
practical tools that are usable in all sorts of situations.

YMMV, but that's my $0.02 worth

Regards,

[Jeffrey Silberman - SurroundWorks(tm)]

----- Original Message -----
From: "Chris Caudle" <***@chriscaudle.org>
To: <***@music.vt.edu>
Sent: Thursday, January 24, 2002 7:33 PM
Subject: [Sursound] ambisonic microphone techniques

Post by Chris Caudle
1) Is anyone doing direct B format recording, meaning using two
figure-of-eight microphones in a M-S arrangement with an added omni
for the W signal?

I have experimented with 2 figure-8's plus omni arrangements. Works
surprisingly well.

Post by Chris Caudle
Josephson even makes a microphone with two selectable
pattern capsules plus an omni capsule in the same housing, so the
technique could be used even without resorting to cumbersome multiple
microphone mounting arrangements like Nimbus seemed to use.
So why do all the ambisonic recordists seem to use the Soundfield?

I have been trying to get the Josephson to let me try a C700S for years in
hopes of buying one, but he apparently builds them to order. Recently, he
stated that I might get to try one.... The SoundField is ideally elegant but
seems to drift out of calibration (invariably mine needs recalibration every
so often- as a rule I send it to Soundfield every 18 months for routine
maintenance and for peace of mind. Now that I have had to replace all 4
capsules, perhaps it will be more stable- time will tell). Furthermore, the
SoundField is undeniably noisey. A digital implemenation is in the works or
so I hear....

Post by Chris Caudle
2) What effect do non-coincident microphones have on ambisonic
recording?
The Soundfield microphone has the capsules as nearly coincident as
possible,
and the ambisonic papers I have been able to read seem to assume
coincident
capsules as the starting point for the mathematical derivations, yet Dr.
Moorer of Sonic Solutions and Jack Vad of the San Francisco Symphony
have
done experimental recordings which utilize what is basically the NOS
technique (hypercardioid microphones at 110deg. and 13cm to 17cm
separation) with an additional rear facing hypercardioid, from which
the horizontal ambisonic signals were derived.
http://www.sonic.com/pdf/wp_aud_RationalBasis.pdf
That paper is the first mention I have seen in print of non-coincident
ambisonic techniques (although admittedly I do not have a lot of
reference material which covers ambisonics in any detail).

If the capsules are vertically aligned, the non-coincidence is effectively
in the vertical domain. In conducting a SoundField vs. 3 vertically aligned
mics in a calibrated walk-around, the 3 vertically aligned mics localized
nearly as well as the SoundField. The fact that the SoundFIeld was far
noisier led one of the experimenters to eschew the SoundField in favor of
Sennheiser MKH mics. The Sennheiser array is more cumbersome and required a
custom mic rig to be fabricated. In addition, the mics had to be specially
calibrated/matched by Sennheiser. The Moorer technique I have not heard
(though I may be able to- come to think of it!)

Post by Chris Caudle
3) Using the the technique described by Dr. Moorer, is any advantage
gained
by using more than three microphones to generate the ambisonic signals?
I think that would in effect be similar to mathematically having three
unknowns but more than three equations constraining the results, i.e.
the
system is overspecified so you have some redundancy of information. In
practice it might have some benefit because you rely on the off-axis
performance of each microphone less, or it may have some disadvantage
because
you have more leakage between microphones, with the resultant phase
cancellation problems.
I am much too rusty on my matrix math to fully follow how Dr. Moorer's
equations could be extended to using four or five microphones. Does
anyone
have a reasonably educated guess as to whether the microphone technique
being developed by Jim Johnston at AT&T research labs is likely using
the
same idea? That array is described as 5 hypercardioid microphones, with
an
angular separation of 72 degrees between each, with two shotgun
microphones
pointed up and down. The array of 5 microphones separates the capsules
by
approximately "the diameter of a human head."

Perhaps, the phasiness associated with spacing the B-Format mic elements may
appeal to some. Not I, since I prefer pinpoint localization, but I am funny
that way. As for the Johnston technique, my experience is that shotgun mics
are very colored- designed for band-limited speech- not music.

[chris woolf]

Post by Chris Caudle
So why do all the ambisonic recordists seem to use the Soundfield?

I do know a couple who construct similar arrays using Schoeps CCM
capsules. They are about the only easily available range of high quality
microphones that allow compact enough arrangements for close coincidence
and reasonable lack of acoustic shadowing (or other distortions from
lumps of microphone body). They are sometimes used in preference to a
Soundfield by these people where weight and location-style suspension is
important.

Chris Woolf

[Kurt Albershardt]

--On Friday, January 25, 2002 8:52 AM +0000 chris woolf

Post by chris woolf
I do know a couple who construct similar arrays using Schoeps CCM
capsules. They are about the only easily available range of high quality
microphones that allow compact enough arrangements for close coincidence
and reasonable lack of acoustic shadowing (or other distortions from
lumps of microphone body). They are sometimes used in preference to a
Soundfield by these people where weight and location-style suspension is
important.

Are you aware of any comercial suspension setups that would accomodate this?
I imagine it would be something similar to an M-S setup but rigged for three
mics?

[chris woolf]

I have supplied Rycote parts to do this (for 4 mics) per occasion. It
isn't requested frequently enough to make a product but its usually
possible to make up a rig from fairly standard components.

Schoeps have a set up for double MS, which is a related technique, again
using our Rycote suspension parts plus an adapter bar of their's. If you
are interested I expect we could discuss how we could make something to
satisfy your requirements.

Chris Woolf

Post by Kurt Albershardt

Post by chris woolf
I do know a couple who construct similar arrays using Schoeps CCM
capsules. They are about the only easily available range of high quality
microphones that allow compact enough arrangements for close

coincidence

Post by Kurt Albershardt

Post by chris woolf
and reasonable lack of acoustic shadowing (or other distortions from
lumps of microphone body). They are sometimes used in preference to a
Soundfield by these people where weight and location-style

suspension is

Post by Kurt Albershardt

Post by chris woolf
important.

Are you aware of any comercial suspension setups that would accomodate this?
I imagine it would be something similar to an M-S setup but rigged for three
mics?

[Mobile webmaster]

Taking some bits of this thread and criticisms adds up to a picture which I
have strong gut feelings about. ('scuse the pun)

Post by Jeffrey Silberman - SurroundWorks(tm)

Post by Chris Caudle
So why do all the ambisonic recordists seem to use the Soundfield?

Because they don't know any better? It's a quick fix?

Post by Jeffrey Silberman - SurroundWorks(tm)

Post by Chris Caudle
Because it works, is quick and easy to set up, has a well-documented

history
and excellent back-up from the company.
Untrue it works for what you want to do, don't generalize.

Neumanns,DPAs, Schoeps etc and all other top quality items also have
excellent backup.
SF is a not very good mic capsule, dead noisy.It's a good way of selling
cheap mics expensively. You could make your own using better capsules.

Post by Jeffrey Silberman - SurroundWorks(tm)

Post by Chris Caudle
I mostly use it for location recording of effects

and music where time and repeatability are of the essence.
What about recording live music?
Do they work really? There is strong evidence they don't do what we are
looking for.
Many have written to this list saying they use them for concert recordings.
1/

Post by Jeffrey Silberman - SurroundWorks(tm)
Perhaps, the phasiness associated with spacing the B-Format mic elements

may
appeal to some. Not I, since I prefer pinpoint localization,

It's the phasiness which makes me feel unwell, and want to develop a better
approach, based on microphone pairs,- typically several pairs of omnis,
hypos, and cardios.
(Why do people want to use figure 8s, is it because of Gerzon?)

Post by Jeffrey Silberman - SurroundWorks(tm)
Josephson even makes a microphone with two selectable
pattern capsules plus an omni capsule in the same housing, so the
technique could be used even without resorting to cumbersome multiple
microphone mounting arrangements like Nimbus seemed to use.

Nimbus is hardly a reference for recording quality, and they mainly used
their own studio in Monmouth, which was a known quantity for them.
I doubt they would have gone far if they had had to record for broadcast and
live.

FYI
We taylor make each set up each time to each auditorium and artist geometry.
This changes a lot when the audience arrives, and this is an additional
element.
There is obviously a lot more work and needs taking terrific risks on the
final result, far more difficult than just merely swinging in a soundfield
or other array of microphones and just saying "this is good,- don't question
it!
That is why I guess so many people are sold on the Calrec SF concept. It
looks simple and sound deceptively good. (Deceptive = disappointing after a
short time, - like the smile on a photo ad, it always curls up and dies
after viewing for a few seconds).
The soundfield is one solution which is always basically the same, sometimes
it works, mostly it doesn't, but it does give you the chance to correct
major mistakes in post mixing, which our approach doesn't.
With ours we only have one shot at it, it has to be a good one, and that
depends heavily on the quality of your hearing on the day in that building
and the ability to adapt immediately to what you hear, including the
difficulty of perception of what is really going on around and behind
you.(So you have to move mics adjust the number/type/delays and record on a
limited number of stereo channels mixed down direct to disk in record time
during rehearsals.)

The single determining factor is human hearing.
After a week or two of live concerts + audio editing, the ear tends to get a
little tired.
Some people reckon you can't get a proper objective judgement on the spot in
that concert hall environment, you have to listen to the recording
elsewhere, in a controlled environment.
I believe you can, but it takes loads of practice and lots of experience
with music,and an ability to think and imagine two steps away from where you
really are.

2/ Objection.
You can't set up the delays with the SF mic, (because it is a single
source).
For surround it is essential to align room size parameter adjustments, to
what the majority of people will find acceptable to listen to in their
homes, and if there are large distances which have to be corrected (eg.
miking a choir, then a large symphony orchestra + a soloist, which we did
with our Brahms requiem recording) you need many more sources than just one.
The result with a SF mic would have been a phasy bathroom in the case I just
cited.
A single source is just not good enough.

3/ >If the capsules are vertically aligned, the non-coincidence is
effectively
in the vertical domain. In conducting a SoundField vs. 3 vertically aligned
mics in a calibrated walk-around, the 3 vertically aligned mics localized
nearly as well as the SoundField.

So why use the SF, which is sub standard for a pro mic?

Post by Jeffrey Silberman - SurroundWorks(tm)
I do know a couple who construct similar arrays using Schoeps CCM
capsules. They are about the only easily available range of high quality
microphones that allow compact enough arrangements for close coincidence
and reasonable lack of acoustic shadowing (or other distortions from
lumps of microphone body). They are sometimes used in preference to a
Soundfield by these people where weight and location-style suspension is
important.

Schoeps also are not as good as people make out...They're very "acidic" in
sound, prefer small Neumanns/DPAs, we've stopped using them.

This is probably a pile of heresy to a lot of the list, but the debate is
really about how to capture "that sound" .Technology has quite simply really
moved on.

GT

[chris woolf]

[Chris Woolf]

Post by chris woolf
I do know a couple who construct similar arrays using Schoeps CCM
capsules. They are about the only easily available range of high quality
microphones that allow compact enough arrangements for close

coincidence

Post by chris woolf
and reasonable lack of acoustic shadowing (or other distortions from
lumps of microphone body). They are sometimes used in preference to a
Soundfield by these people where weight and location-style suspension is
important.

[GT]
Schoeps also are not as good as people make out...They're very

"acidic" in

sound, prefer small Neumanns/DPAs, we've stopped using them.

Aside from subjective preferences - which I don't want to touch on - the
Neumann KM100 series (which is excellent) is only available in remote
cable form, not a compact design, which does have considerable relevance
for the people I was describing. The DPA 4020/4030 series (also greatly
respected) suffer from slightly greater self-noise and are limited to
omni and cardioid configurations.

I'm delighted that you like the (alkaline?) Neumann and DPA devices but
they cannot be substituted for the Schoeps CCMs in every instance.

Chris Woolf

[seva]

Post by Mobile webmaster
We taylor make each set up each time to each auditorium and artist geometry.

who is taylor?


























=)

[Goran Finnberg]

Post by Mobile webmaster
SF is a not very good mic capsule, dead noisy.It's a good way of selling
cheap mics expensively. You could make your own using better capsules.

The noise of the 250 simply makes it unusable to me.

A pair of Schoeps is so quiet to my ears that the 250 can simply be
described as "hissy".

[Culann mac Caba]

Interesting views on the need for/practical usefulness of Soundfield mics...
Our experience at Cuan is that they are very noisy and that's just the way
it is... We use an old Calrec one which is extremely noisy and drifts way
out of calibration with time. Still highly convenient for background-type
atmospherics and probably the best shot at coincidence there is...

For acoutic music work, we use two techniques:
1 Our DIY B Format mic is essentially to 414s at right angles, with a U87
omni above them (horizontal only). Issues arising include time and level
calibration - we have devised an MLS-based real-time calibration system set
up to optimize the array's pick-up for the chosen "focus point" in the live
room (usually the main instrument if solo, or "centre stage" if wide area).
The calibration corrects for level differences in the individual capsules
and the time alignment really helps improve coherency, to a (frequency)
point... The really excellent thing is that, as a stimulus signal, we often
just ask the player to play - the real-time cross-correlation required does
not necessarily need a white stimulus...

2 We have a semi-permanent array of mics set up in the live room, which
we have placed using purely room-acoustical criteria (ie where does the room
sound best and how). Knowing the positions (including height) of the mics,
we process them in DSP to achieve a "wide area" B Format composite output.
We usually also sound out each Mic/B Format W channel and cross-correlate to
get at the delay to each mic. We then use these numbers to "normalize" the
array with respect to time alignment - tedious but it's a once-off for each
session and well worth it...

It's all pragmatic and not as exact as the theory books... which to us has a
ring of real world about it which we like. And, at the end of the day, in
the control room it sounds great! Info at http://www.cuan.com/bsystem.html

Culann.

--
Culann mac Caba
Technical Director
Cuan.

----- Original Message -----
From: Goran Finnberg <***@telia.com>
To: <***@music.vt.edu>
Sent: 25 January 2002 14:01
Subject: Re: [Sursound] ambisonic microphone techniques

Post by Goran Finnberg

Post by Mobile webmaster
SF is a not very good mic capsule, dead noisy.It's a good way of selling
cheap mics expensively. You could make your own using better capsules.

The noise of the 250 simply makes it unusable to me.
A pair of Schoeps is so quiet to my ears that the 250 can simply be
described as "hissy".
--
Best,
Goran Finnberg
The Mastering Room AB
Goteborg
Sweden
_______________________________________________
Sursound mailing list
http://mail.music.vt.edu/mailman/listinfo/sursound

[Jeffrey Silberman - SurroundWorks(tm)]

----- Original Message -----
From: "Culann mac Caba" <***@cuan.com>
To: <***@music.vt.edu>
Sent: Friday, January 25, 2002 7:03 AM
Subject: Re: [Sursound] ambisonic microphone techniques

Post by Culann mac Caba
It's all pragmatic and not as exact as the theory books... which to us has a
ring of real world about it which we like. And, at the end of the day, in
the control room it sounds great! Info at

http://www.cuan.com/bsystem.html

What is the prospect of the "bsystem" being made commercially available on
the TC6000 platform?

[Kurt Albershardt]

--On Friday, January 25, 2002 12:56 PM +0100 Mobile webmaster

Post by Mobile webmaster
Why do people want to use figure 8s, is it because of Gerzon?

Some of us _like_ the sound of figure-8 microphones, both for their lack of
off-axis coloration in comparison to most directional mics and their ability
to capture room sound.

[Goran Finnberg]

Post by Kurt Albershardt
Some of us _like_ the sound of figure-8 microphones, both for their lack of
off-axis coloration in comparison to most directional mics and their ability
to capture room sound.

And what about the lack of low frequency reponse inherent in the
pressure gradient mode.?

This lack gives a response that is down between -12 to -16 dB at 40 Hz.

Makes recordings of the pipe organ sounds thin and lacking in body.

[Kurt Albershardt]

--On Friday, January 25, 2002 6:40 PM +0100 Goran Finnberg

Post by Goran Finnberg

Post by Kurt Albershardt
Some of us _like_ the sound of figure-8 microphones, both for their lack
of off-axis coloration in comparison to most directional mics and their
ability to capture room sound.

And what about the lack of low frequency reponse inherent in the
pressure gradient mode.?
This lack gives a response that is down between -12 to -16 dB at 40 Hz.

The original post suggested that cardioids (and hypo-/hyper- variants as
well) were somehow inherently superior to figure-eights. That lack of LF
response applies to all pressure gradient designs of course.

Post by Goran Finnberg
Makes recordings of the pipe organ sounds thin and lacking in body.

A pressure gradient design would not be my first choice for recording a pipe
organ, at least in the lower registers.

[Mobile webmaster]

True

I use KM100 series most of the time with passive cables, and we get superb
results with them for precisely the reasons you describe. Wonderful open
natural ambience particularly with mixed voice/instruments.

We used to use Schoeps a lot in stereo pairs, but I don't rate them as
highly and the omnis are nothing like as clean as the Neumann/ too many bad
compromises and equalisation/rejection too match, so we stopped a couple of
years ago.

The discovery of year 2001 was the KM143, which very few people use.
For surround it gives EXACTLY what we are looking for, a beautiful
compromise between forward and rear rejection with a bit of directivity.
This means we can mike up the rear channels to match, without the troubles
caused by pure omni or cardio.

GT

Post by chris woolf

[Chris Woolf]

Post by chris woolf
I do know a couple who construct similar arrays using Schoeps CCM
capsules. They are about the only easily available range of high

quality

Post by chris woolf
microphones that allow compact enough arrangements for close

coincidence

Post by chris woolf
and reasonable lack of acoustic shadowing (or other distortions from
lumps of microphone body). They are sometimes used in preference to a
Soundfield by these people where weight and location-style suspension

is

Post by chris woolf
important.

[GT]
Schoeps also are not as good as people make out...They're very

"acidic" in

sound, prefer small Neumanns/DPAs, we've stopped using them.

Aside from subjective preferences - which I don't want to touch on - the
Neumann KM100 series (which is excellent) is only available in remote
cable form, not a compact design, which does have considerable relevance
for the people I was describing. The DPA 4020/4030 series (also greatly
respected) suffer from slightly greater self-noise and are limited to
omni and cardioid configurations.
I'm delighted that you like the (alkaline?) Neumann and DPA devices but
they cannot be substituted for the Schoeps CCMs in every instance.
Chris Woolf

[Mobile webmaster]

He is rich.

Post by seva

Post by Mobile webmaster
We taylor make each set up each time to each auditorium and artist

geometry.

Post by seva
who is taylor?

[G***@aol.com]

Gordan,

Any chance you've compared a Mark V? Same, better, worse?
-- Gary

In a message dated 1/25/02 5:58:14 AM, ***@telia.com writes:

<< > SF is a not very good mic capsule, dead noisy.It's a good way of selling

Post by Mobile webmaster
cheap mics expensively. You could make your own using better capsules.

The noise of the 250 simply makes it unusable to me.

A pair of Schoeps is so quiet to my ears that the 250 can simply be
described as "hissy".

[Angelo Farina]

I have just replaced an MKV with a new ST-250. Having simpler electronics
and no knobs, its is much more stable, and does not go out of calibration so
easily. And there is no gain knob, so once You calibrated it (in an anechoic
chamber, unfortunately it is not easy to fir a standard calibrator on it),
You are in the position to know almost exactly the absolute sound pressure
level.
The ST-250 is quite noisy when battery powered (or phantom supply powered),
but when You give 220 V AC mains to its control box, and wait 15 minutes for
the microphone to warm up properly, then the noise goes away almost
completely. Of course this is not practical for site recordings...
In any case, I suppose that the good solution is to intercept the A-format
signals before the SF control unit, and process them digitally.
What I would really like would be the availability on the market of the
AGM-MR2 microphone (http://www.agmworld.com/agm-mr2.htm): B&K (DPA)
capsules, digital processing, a calibrator can be mounted on them, etc....
Bye!

Angelo Farina
----- Original Message -----
From: <***@aol.com>
To: <***@music.vt.edu>
Sent: Friday, January 25, 2002 5:49 PM
Subject: Re: [Sursound] ambisonic microphone techniques

Post by G***@aol.com
Gordan,
Any chance you've compared a Mark V? Same, better, worse?
-- Gary
<< > SF is a not very good mic capsule, dead noisy.It's a good way of selling

Post by Mobile webmaster
cheap mics expensively. You could make your own using better capsules.

The noise of the 250 simply makes it unusable to me.
A pair of Schoeps is so quiet to my ears that the 250 can simply be
described as "hissy".
--
Best,
Goran Finnberg >>
_______________________________________________
Sursound mailing list
http://mail.music.vt.edu/mailman/listinfo/sursound

[Jeffrey Silberman - SurroundWorks(tm)]

----- Original Message -----
From: "Angelo Farina" <***@pcfarina.eng.unipr.it>
To: <***@music.vt.edu>
Sent: Friday, January 25, 2002 1:38 PM
Subject: Re: [Sursound] ambisonic microphone techniques

Post by Angelo Farina
What I would really like would be the availability on the market of the
AGM-MR2 microphone (http://www.agmworld.com/agm-mr2.htm): B&K (DPA)
capsules, digital processing, a calibrator can be mounted on them, etc....

Despite the website information, I don't believe this mic has ever been
available for hire (or purchase for that matter), correct me if I am wrong.
I do have the lone (to my knowledge) commerical recording using this mic:
Grieg & Sibelius String Quartets on the AGM#980101 New Media "label" (1998)
(Probably UHJ encoded but no so stated). I

[Mobile webmaster]

Figure of 8 is basically 2 back to back omnis.
In this config it is normal not to have coloration, but not much
directivity.
The directivity is produced by the rear part of the 8 information derived
from 2 or more.

Figure of 8 are symmetric in their characteristics which means the front and
rear sensitivities are equal.

The demands of rear information are surely completely different from the
front, especially in a surround situation- I mean we don't for instance want
to reproduce the audience in the same way as the artist.
We use another mic array or pair for that and it is not in the same spot.
(negative delay is introduced for distance compensation)

That is why we like either 2 dissimular seperate capsules, with phase
inversion or hypo characteristic (wide oval omni).

GT

Any good?

Post by Kurt Albershardt

Post by Mobile webmaster
Why do people want to use figure 8s, is it because of Gerzon?

Some of us _like_ the sound of figure-8 microphones, both for their lack of
off-axis coloration in comparison to most directional mics and their

ability

Post by Kurt Albershardt
to capture room sound.

[Marco Olivotto]

Post by Mobile webmaster
Figure of 8 is basically 2 back to back omnis.

You're joking, aren't you? :-)
Put two omnis back to back and what you have is double intensity signal,
always omni.
Phase shift one of them by 180° and what you have is silence due to
phase cancellation.
All this in a perfect world, of course.
Omnis react to air pressure, figure of 8's react to air pressure
*gradients*. Totally different beasts...
Omnis' sensitivity (normalised) is S=1. Figure of 8's sensitivity
(always normalised) is S=cos(theta), where theta is the angle of the sound
source wrt to the capsule. No way you can get directional information with
coincident omnis: either S=2 or S=0 depending on the phase.

Marco
---
Marco Olivotto
Sonica Studios
16 Via dell'Abetone
38068 ROVERETO (TN)
ITALY
Tel/Fax: [phone]
---
Visit www.sonicastudios.com - finally updated, up and running!

[Bob Cain]

Post by Marco Olivotto

Post by Mobile webmaster
Figure of 8 is basically 2 back to back omnis.

You're joking, aren't you? :-)
Put two omnis back to back and what you have is double intensity
signal, always omni.

If you space them within a quarter wavelenth of the highest frequency of
interest, subtract their outputs and integrate the result you get a
gradient mic with a fig 8 pattern. They have to be pretty small to make
that work though and small implies noisy.


Bob
--
"Things should be described as simply as possible, but no simpler."

A. Einstein


////////////////////////////////////////\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\

To contribute your unused processor cycles to the fight against cancer:

http://www.intel.com/cure

\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\///////////////////////////////////////

[Goran Finnberg]

Post by Bob Cain
They have to be pretty small to make
that work though and small implies noisy.

Which simply means that its not realizable as something that can be used
for the recording of music then.

[Kurt Albershardt]

--On Friday, January 25, 2002 5:57 PM +0100 Mobile webmaster

Post by Mobile webmaster

Post by Kurt Albershardt

Post by Mobile webmaster
Why do people want to use figure 8s, is it because of Gerzon?

Some of us _like_ the sound of figure-8 microphones, both for their lack of
off-axis coloration in comparison to most directional mics and their
ability to capture room sound.

Figure of 8 is basically 2 back to back omnis.

Actually in its most basic form it is simply an open diaphragm. Its frontal
response is indeed circular, but the side nulls make for some useful setups,
particularly in certain positions.

Post by Mobile webmaster
Figure of 8 are symmetric in their characteristics which means the front and
rear sensitivities are equal.

This can ideed present some challenges, and is probably the primary reason
_not_ to use them for many tasks.

Post by Mobile webmaster
That is why we like either 2 dissimular seperate capsules, with phase
inversion or hypo characteristic (wide oval omni).

So do I, for many tasks. I just happen to like figure-eights for some as
well.

[Goran Finnberg]

Post by Mobile webmaster
Figure of 8 is basically 2 back to back omnis.

Really???

[seva]

Post by Goran Finnberg

Post by Mobile webmaster
Figure of 8 is basically 2 back to back omnis.

Really???

hey, let's just ask taylor, the rich guy!

he's probably smart too, and can spell!

and he's probably not racist!

[Angelo Farina]

----- Original Message -----

Post by Goran Finnberg

Post by Mobile webmaster
Figure of 8 is basically 2 back to back omnis.

Really???

I can give some more technical info here.
First of all, we must understand that the physical quantity which should be
captured by an ideal "figure of eight" microphone is not the pressure p, but
instead it is the particle velocity v.
The Euler's equations relate the pressure GRADIENT to the particle velocity.
Along a given axis, You can get the component of the particle velocity
vector. Let's consider the X axis for simplicty. Then, following Euler, we
have:
dp/dx=-rho*dv/dt
where rho is the air density, and t is time.
Now, it is possible to get the velocity from a pair of pressure microphones
(this is technique normally employed in sound intensity proboes, such as the
ones manufactured by Bruel & Kjaer - I have a couple of them). Rearranging
the Euler's equation, we get:
u=-1/rho*Integral(dp/dx)*dt
(excuse me for the symbolism)
The gradient dp/dx is simply approximated as the finite difference: dp/dx
=(p1-p2)/L, where L is the spacing between microphones. In a typical B&K
probe, the microphones are mounted face-to-face, with a solid spacer between
them, having a thickness of 12 mm. This gives an usable frequency range
between 100 hz and 5 kHz.
So, from the difference between two closely spaced pressure transducers it
is effectively possible to get the velocity signal, but You also need to
time-integrate this difference.
This is a very crude approach, of course: instead of the linear
approximation employed in the above equation it is possible to make
something better. The theory developed by Gerzon and Craven, and employed in
the Soundfield microphone, is really smart, because they used an
higher-order approximation for the gradient (including also second order
terms), and this extends significantly the frequency range. Recently also
Bruel & Kjaer moved to this advanced approach, and on their newest Sound
Intensity analyzer (type 2260 Investigator), now an "extended frequency
range" mode is available, which makes the same 12mm spaced probe to work
between 80 and 10000 Hz. They did not poublish yet the details of their
trick, but I am quite sure that they simply employed the Soundfield
equations.
Of course, the B&K system does all the computations digitally inside the
analyzer, so the velocity signal which comes out is remarkably quieter than
other analog approaches.
I also suggest that all You read the fundamental paper of Mark Poletti,
appeared on the Journal of AES at the end of 2000. He generalized the above
formulation to any number of microphones placed along a circle, and having
arbitrary directivity (not only omnidirectional). With the Poletti's theory,
it is possible to synthesize virtual microphones of higher order (more
directive).
What is lacking now is a generalization of his theory for a
three-dimensional microphone distribution (i.e., a sphere), which would
allow to derive, for example, a 2-nd order B-format signal (a 9-channels FMH
wave file).
Bye!

Angelo Farina

[Goran Finnberg]

Post by Mobile webmaster
In this config it is normal not to have coloration, but not much
directivity.

Really??

[Mobile webmaster]

I was talking about characteristics, not what would actually happen if you put two omni mics back to back obviously.
Such a synthesis would actually be quite to achieve with 2/4 mics.

The proof of this theory is what happens if you use 2 figure 8s as A B or X/Y

GT

Post by Mobile webmaster
Figure of 8 is basically 2 back to back omnis.

You're joking, aren't you? :-)
Put two omnis back to back and what you have is double intensity signal, always omni.
Phase shift one of them by 180° and what you have is silence due to phase cancellation.
All this in a perfect world, of course.
Omnis react to air pressure, figure of 8's react to air pressure *gradients*. Totally different beasts...
Omnis' sensitivity (normalised) is S=1. Figure of 8's sensitivity (always normalised) is S=cos(theta), where theta is the angle of the sound source wrt to the capsule. No way you can get directional information with coincident omnis: either S=2 or S=0 depending on the phase.

Marco
---
Marco Olivotto
Sonica Studios
16 Via dell'Abetone
38068 ROVERETO (TN)
ITALY
Tel/Fax: [phone]
---
Visit www.sonicastudios.com - finally updated, up and running!

[Goran Finnberg]

Post by Mobile webmaster
The proof of this theory is what happens if you use 2 figure 8s as A B or X/Y

And what happens then may I ask?

[Marco Olivotto]

Hum. Either I lost something along the way, or I am getting incredibly
confused.

Post by Mobile webmaster
I was talking about characteristics, not what would actually happen if you

put two omni mics back to back >obviously.

You mean re: colouration? Can't quite get this one... omnis (single
diaphragm) are usually and by nature less coloured than any pressure
gradient microphone - including figure of 8s. And moreover they suffer less
from proximity effect.

Post by Mobile webmaster
Such a synthesis would actually be quite to achieve with 2/4 mics. The

proof of this theory is what happens if >you use 2 figure 8s as A B or X/Y

Completely lost here... X-(
Would you like to elaborate a bit more on this point? I can't see a way
to get an "omni" from two figure of 8's, no matter how you try. Or maybe I
can't quite get what you're talking about, sorry.

Marco
---
Marco Olivotto
Sonica Studios
16 Via dell'Abetone
38068 ROVERETO (TN)
ITALY
Tel/Fax: [phone]
---
Visit www.sonicastudios.com - finally updated, up and running!

[Goran Finnberg]

omnis (single diaphragm) are usually and by nature less coloured than any pressure
gradient microphone - including figure of 8s. And moreover they suffer less from proximity effect

BTW, there´s simply no proximity effect at all in a true pressure
actuated mic, ie omni, at all.

Km83, M50, mk2 etc.

[Robin Miller, Filmaker]

More precisely, a Figure 8 is 2 back-to-back cardioids mixed equally with
one out of phase - and you can "make" one just this way. Singly, a mic with
this pattern can be made precise, which explains its reputation for being
"uncolored," is highly directional in attentuating sides, but requires EQ of
its lows. An orthogonal pair (Blumlein or B-format) Figure 8s combine for
omnidirectional energy distribution, which for recordists means a natural
but uncontrollable stage + hall balance.
Robin

Post by Mobile webmaster
Figure of 8 is basically 2 back to back omnis.

In this config it is normal not to have coloration, but not much
directivity.
The directivity is produced by the rear part of the 8 information derived
from 2 or more.

Figure of 8 are symmetric in their characteristics which means the front and
rear sensitivities are equal.

The demands of rear information are surely completely different from the
front, especially in a surround situation- I mean we don't for instance want
to reproduce the audience in the same way as the artist.
We use another mic array or pair for that and it is not in the same spot.
(negative delay is introduced for distance compensation)

That is why we like either 2 dissimular seperate capsules, with phase
inversion or hypo characteristic (wide oval omni).

GT

Any good?

Post by Mobile webmaster

Post by Mobile webmaster
Why do people want to use figure 8s, is it because of Gerzon?

Some of us _like_ the sound of figure-8 microphones, both for their lack of
off-axis coloration in comparison to most directional mics and their

ability

Post by Mobile webmaster
to capture room sound.

[Stephen Barncard]

I was forwarded this from an attorney friend of my who is working
with Herbert Waltl. I have another article to follow about this same
project. Sorry about the length but I thought it has some relevance
on this list. I have nothing to do with this or endorse (or not
endorse) this project. Comments welcome.

Below is another article about our productions with Chick Corea, to be
published by AUDIO MEDIA - probably in the next issue,
Best regards,
Herbert Waltl
media HYPERIUM
office: 310 - 378.1078
studio: 310 - 891.0006
cell: 310 - 891.0006

--------------------

The best parties are the ones that people are still talking about years
later, and cornerstone jazz pianist Chick Corea has made sure that
everyone will be hearing about his 60th birthday bash for quite a while.
Corea held his celebration at New York Citys legendary Blue Note,
performing 36 shows with his highly illustrious friends over 18 nights
and specifying the extra-accurate Direct Stream Digital (DSD) format to
record every second.

As DSD, with its one-bit recording process and sampling rate of 2.8224
mHz for a frequency response of 100 kHz, begins to take root in the
global music catalog, the number of studio sessions and remixes for the
Super Audio CD (SACD) consumer format is steadily growing. Live DSD
recordings, however, have been very few and far between, which only
added to the fun for LA-based audio production company Media Hyperium
(www.mediahyperium.com). Every DSD recording is an adventure, because
every setup is totally new, points out Herbert Waltl, CEO/Senior
Producer for Media Hyperium. Theres no job where you can say, Back
then, we did it like that.

As an early experimenter in 5.1 and 7.1 Surround, as well as DVD video,
Waltl was well prepared for this new experience. However, the odd shape
of the Blue Note's room (long and narrow with a small stage on the
side), untested DSD software, plus random factors like surprise guests
(including Chaka Khan, Isaac Hayes, Bella Fleck and Liza Minelli, among
others) and a silverware-clinking audience lent the Corea bash a host of
problems that needed solving.

Helping Waltl, Chief Engineer Clark Germain, and Assistant Engineer Ted
White get off the ground was the innovative Pyramix DSD software created
by Merging Technologies and Philips. This is the very first time that a
DSD system can do 16 tracks, Waltl reports. Sadies can only do two
tracks, and theres Sonoma from Sony, which is good but only does eight
tracks. With Pyramix, the interface is very familiar. It doesnt look
too exotic, and everything is available instantly.

Media Hyperium set up their comfortable command center upstairs from the
action in the office of the clubs manager, running cable to the stage
through a back stairwell and watching the action via a previously
installed video monitor. In his best-case scenario, Germain would have
made his console out of a pair of vintage Neve BCM10 sidecars.
Disappointingly, not only did those prove impossible to procure in NYC,
he was also stymied in his search for a desk of acceptable quality
available locally. Eventually, he obtained a delicious API 1604 console
from LAs Classic Equipment Rentals and had it shipped east.

I love the way it sounds the Class A electronics, Germain says of
the API. Im an analog guy, and I do mostly analog recording for high
fidelity jazz. Digital is not as warm as analog, but when Im working
with digital I like to get as warm a sound as I can. Here, its all
about having the biggest, fattest sound going into it, because DSD is
able to reproduce that.

Noticeably absent from Media Hyperiums temporary recording room was a
separate rack of effects for sound processing. Instead, Germain depended
on the API mic pres and a short list of hand picked microphones to
deliver the sound to eight Seagate 36 gig hard drives. The choice of
microphones was very important, he confirms. If I were live in a
studio, I could get much more sensitive mics, baffle them off, and it
would be fine. But here its a very small stage with a reflective brick
wall behind it, so I have to balance between the sensitivity of the mics
and the polar response off-axis.

On a night where Corea appeared with vibes innovator Gary Burton, the
dynamic interplay between the two was brought out by a stereo pair of
Schoeps CMC 5U mics on Coreas 9 ½ foot Yamaha grand piano, plus a pair
of DPA 441s and another pair of Schoeps CMC 5Us on Burtons vibes.
Meanwhile, a Royer stereo mic and two DPA 4000s served as room mics. All
mics were rented from Dreamhire.

Tonight, these are two acoustic instruments that sound good and you
want to make them sound even, Germain says simply. You dont want too
much of one in the other. As far as placement goes, Ive recorded pianos
for years now, so I had an idea of where to start. Given that its a
club situation, you have to be closer than in a studio. Piano micing is
all about phase relationship: Sound is bouncing around, so you want to
be as phase-coherent as possible. I prefer to use a pair, taking the
high mic and facing it up near the hammers and angling towards the
higher string. The lower mic will come back some heading down to the low
strings, by the low soundboard. The result is a fairly close, warm sound
where you dont get too much leakage.

With the size and makeup of the band changing constantly around Corea
every two nights, the Media Hyperium crew needed to stay flexible. Going
from a duo to a sextet, then maybe back to a three-piece meant mic
configurations and mindsets were constantly changing. Its the same
setting, but theres no continuity, Waltl says. Its changing, and
Corea and his friends are improvising a lot. Suddenly they decide to
stop and do something completely different, and we have to go with the
flow.

The AD/DA converters on location consisted of a set of EMM Labs
(Meitner) units as well as DCD converters, each group going to Tascam
DA98 machines recording to Fuji DPD-113MP tape for backup. Once the last
note of the marathon birthday bash has sounded the mountain of media
will be reviewed by Corea, who will note the best performances. After
that, the ball is back in Media Hyperiums court at their comprehensive
LA facility, for SACD mixing and mastering as well as marrying the audio
to video footage shot throughout the event for in-house DVD authoring.

If the sounds that came out of the Genelec 1031 monitors upstairs at the
Blue Note are any indication, the DSD capture of Chick Coreas monster
party should stand as one of the most crisp, vibrant live jazz
recordings ever made. The idea is youre not saving time or taking
shortcuts youre improving on the sound, notes Germain. It looks
like a garage in here, but its a very hi-fi garage! Who knows if youll
get a second chance to record so many stars together on 16 tracks in
DSD? This is a once in a lifetime event.

David Weiss

[Garry Margolis]

For the purposes of this list, it should be noted that the sessions
at the Blue Note were neither miked nor monitored with surround
techniques because of the inhospitable acoustical environments for
both recording and monitoring. The surround mixes will be created in
post-production.

Garry, who attended the first night's sessions as a representative of Philips

[Goran Finnberg]

Post by Robin Miller, Filmaker
An orthogonal pair (Blumlein or B-format) Figure 8s combine for
omnidirectional energy distribution, which for recordists means a natural
but uncontrollable stage + hall balance.

Which is simply not true at all since the back of the fig-eight is out
of phase with the front so for random incidence we would see part
cancellation of the ambience instead as compared to an omni.

Post by Robin Miller, Filmaker
omnidirectional energy distribution

And what will the pressure gradient loss at LF do to the energy
distribution where the phase shift acting on the membrane will be at its
weakest force?

Post by Robin Miller, Filmaker
but uncontrollable stage + hall balance.

In what way?

It is a simple matter to go out and change the mic placement in relation
to the stage to control this.

Controls the stage + hall balance very well in my experience.

[Jeffrey Silberman - SurroundWorks(tm)]

----- Original Message -----
From: "Robin Miller, Filmaker" <***@dellepro.com>
To: <***@music.vt.edu>
Sent: Friday, January 25, 2002 9:57 AM
Subject: RE: [Sursound] ambisonic microphone techniques

Post by Robin Miller, Filmaker
More precisely, a Figure 8 is 2 back-to-back cardioids mixed equally with
one out of phase - and you can "make" one just this way. Singly, a mic with
this pattern can be made precise, which explains its reputation for being
"uncolored," is highly directional in attentuating sides, but requires EQ of
its lows. An orthogonal pair (Blumlein or B-format) Figure 8s combine for
omnidirectional energy distribution, which for recordists means a natural
but uncontrollable stage + hall balance.

Pearl Microphones makes a mic (TL44?) which contains back-to-back cardioids
so one can have a forward facing card, a rear facing card or a figure-8.
The Josephson C700 contains a forward facing figure-8 and an omni mounted
underneath so one can blend in post the two reponses to suit one's
unidirectional preference.

[Mobile webmaster]

I did say "basically", but as the other contributor points out, pressure
gradient changes a whole load of things . (Most guides try to explain it in
similar terms).
The steep roll off at low frequencies is similar to cardio, the f/b
sensitivity looseley similar to an omni.

It's all together an interesting situation, as the contributor states

Post by Mobile webmaster
Figure of 8 are symmetric in their characteristics which means the front

and

Post by Mobile webmaster
rear sensitivities are equal.

This can indeed present some challenges, and is probably the primary reason
_not_ to use them for many tasks.

Which is why I asked why use them at all?

Post by Mobile webmaster

Figure of 8 is basically 2 back to back omnis. but only in an attempt to

define some loose characteristics, not what would happen if you did that
physically...... "ie. theory not practice".
NEVER did I suggest actually doing that, that would be stupid, especially
not in coincident as it wouldn't work at all.

Post by Mobile webmaster
In this config it is normal not to have coloration, but not much
directivity.

Well the terminology is confusing, we were comparing off-axis coloration in
comparison to most directional mics and their abilities, not what the mics
were absolutely capable of doing.
Clearly we are intererested by the subject of the thread in what happens off
axis. Nothing else.

GT

Really??

Post by Mobile webmaster
Really???
--
Best,
Goran Finnberg
The Mastering Room AB
Goteborg
Sweden

[Stephen Barncard]

I know there's some PR hype here, but still interesting...
sqb

Draft #4 Chick Corea at the Blue Note
01-21 FINAL version
Approx. 1,300 words
Bruce Tucker
732.846.8712
***@verizon.net

Charles Conte (for Tannoy & DPA) ***@home.com


Live at the Blue Note:
Chick Corea and Friends in a Series of High-Def Recordings
On December 23rd, an extraordinary musical experiment concluded at
the storied Blue Note jazz club in New York's Greenwich Village.
Chick Corea, one of the major jazz pianists to emerge in the past
thirty years, wound up a three-week stint during which he played with
nine different line-ups.

An equally extraordinary audio experiment also concluded. For the
first time anywhere - live or in a studio - an audio production team
recorded in 16-track Direct Streaming Digital (DSD), the recording,
editing, and playback technology behind the Super Audio Compact Disc
(SACD). Among the shifting line-up of microphones used over the
course of three weeks of live recording, three DPA units played
crucial roles - the 4041-T omni tube mic (part of a DPA 3532-T A-B
stereo tube mic kit, available to the recording team), and a pair of
4021 Compact cardioid mics. The 4041-T was used mainly on the upright
bass, and the 4021's as a spaced pair for room mics.

Mr. Corea's various ensembles included duos with Bobby McFerrin and
the pianist Gonzalo Rubalcaba; a trio called "Now He Sings, Now He
Sobs" with Roy Haynes and Miroslav Vitous; a tribute to the late,
legendary be-bop pianist Bud Powell with Roy Haynes, Christian
McBride, Joshua Redman, and Terence Blanchard ; and Mr. Corea's
current group, Origin.

The audio team, underwritten by Phillips Electronics NV, was led by
producer Herbert Waltl, CEO and chief producer of Torrance, CA-based
Media Hyperium. Waltl, chief engineer Clark Germain, and assistant
engineer Ted White had to capture the live sound of these changing
groups as well as the impromptu performances of the many guest stars
who dropped by to join in the three-week musical celebration of Mr.
Corea's 60th birthday. Among the luminaries, each presenting a
unique acoustic challenge, were George Benson, Bela Fleck, Wallace
Rooney, Diana Reeves, Isaac Hayes, Paul Schaeffer, Sherry Allen,
Chaka Khan, and Doug E. Fresh.

To complicate matters further, a film crew was shooting every other
night. Produced by Jon and Peter Shapiro of Ideal Entertainment and
directed by David Niles of Colossalvision, the film will ultimately
result in a two-hour documentary and a companion DVD along with a
two-disc, hybrid SACD set in 5.1 Surround Sound (playable on any CD
or DVD player, as well as an SACD player).

"Our goal was to reproduce the experience of these performances in
the highest fidelity possible," says Waltl. "Every night there were
magical moments and our job was to capture them - for the recording
and for the film. We have so many great performances on tape, that we
are discussing the opportunity to release additional titles, possibly
a complete box set of nine discs, one disc for each line-up."

Pioneering the first 16-track DSD recording required some ingenuity.
Swiss-based Merging Technologies provided their PYRAMIX software, and
designed a system to coordinate two 8-track DSD systems, creating a
virtual 16-track machine.

"To my knowledge no one has ever locked together two 8-track DSD
machines in this way," says Germain. "We had two separate computers,
one for each 8-track machine, driven by the PYRAMIX software."

The live setting presented unique challenges that went beyond
audience noise. The stage of the Blue Note is small and on most
nights it was crowded with musicians and instruments. "I had a
conversation with Chick before starting this project," says chief
engineer, Germain, "and he explained to me that, if possible, he
wanted to have the piano on full stick. He also said that given the
size constraints of the stage at the Blue Note and the fact that they
would be filming the event, he didn't want to use any baffling
between the instruments. Given these preconditions, I knew the
microphones would play an extremely important part of the recording
process."
Waltl and Germain chose the DPA 4041-T omni tube mic for the upright
bass, an instrument notoriously difficult to mike and record in a
live ensemble setting.

"The 4041-T provides a much fuller frequency response than other
mikes," says Germain. "And it performed exceptionally well on the
bass here."

Germain chose the tube-bodied model, vs. the solid state 4041-S.
"I've always been a big fan of older tube mics," he says. "I've
used this model on pianos and other instruments in the studio and
like it so much that I haven't gotten around to comparing it with the
solid state version."

For miking the room, the team chose two DPA Type 4021 compacts, the
world's smallest studio quality cardioid condenser microphone. In
addition to the sound quality of the 4021, produced by the same type
of cartridge as the full-sized 4011, its small size - 35 mm by 19 mm
- was ideal for a film setting that required the fewest possible
visual obstructions.

"The compact size of the 4021's and the bendable SM4000 Suspension
Mount proved valuable when it came to placing the room mics," says
White. "Clark was able to use the 'cork screw' end of the mounting
system to secure the microphones to the drop ceiling, which is made
of a very pliable and porous material. It was quite easy to screw the
mount to the ceiling in such a way that did not cause any damage to
the ceiling or the microphone. The result was an exact and very low
profile placement, which was also unobtrusive to the video crew."

With equipment arriving from Los Angeles, New York, the Netherlands,
and Switzerland, the team had only one day to set up before the first
performance.

[Goran Finnberg]

Post by Mobile webmaster
The steep roll off at low frequencies is similar to cardio,

Sorry no.

Since a cardioid is composed of 50% omni and 50 % fig-8 then the bass
rollof will be much less for a cardioid then for a pure pressure
gradient mic as the fig-8 is.

Post by Mobile webmaster
the f/b
sensitivity looseley similar to an omni.

But there´s a polarity flip between the front and the back of the mic so
they will behave very differently in a real room compared to an omni.

[Stephen Barncard]

With all due respect to the Ambisonics and live recording members of
the list, I'd also appreciate hearing about the experiences of people
that are remixing analog masters of hit albums for 5.1, etc. (with
the limited budgets that go along with it), and how they are doing
it....

I would think that this kind of product will at least in the
beginning define the market, especially when surround is installed
routinely in autos.

[Eberhard Sengpiel]

Stephen Barncard wrote:

I would think that this kind of product will at least in the beginning
define the market, especially when surround is installed routinely in autos.


Very interesting: is there really a beginning of surround sound now? - in
cars?

I once was more optimistic.

Eberhard Sengpiel
mailto:***@t-online.de
http://www.sengpielaudio.com

[K. K. Proffitt]

Most of the "surround sound" in automobiles now it being touted by Harman. This
involves upmixing with Logic 7 and is less than satisfactory for much program
material, especially classical.


--
Regards,
K.K.Proffitt
chief audio engineer, JamSync, Nashville
http://www.jamsync.com

Post by Eberhard Sengpiel
I would think that this kind of product will at least in the beginning
define the market, especially when surround is installed routinely in autos.
Very interesting: is there really a beginning of surround sound now? - in
cars?
I once was more optimistic.
Eberhard Sengpiel
http://www.sengpielaudio.com
_______________________________________________
Sursound mailing list
http://mail.music.vt.edu/mailman/listinfo/sursound

[Angelo Farina]

This is true, but they are not the only... Also ASK Industries (the Italian
company which often supports my research in automotive audio) is working
hard for surround applications in cars, and the results are encouraging.
I have listened to the logic 7 demo car at the 19th AES conference, and it
was indeed quite impressive. I did not like the "logic steering" feature
with my preferred recordings (which are spaced-omnis, preferably with a
sphere dummy head) because the steering logic is simply amplitude-based (it
works fine with coincident techniques, it is a sort of Ambisonics steering).
Fortunately, it was possible to switch off the steering logic, leaving all
the other surround synthesis working, and at that point the car was very
pleasant for me.
I hope to be able to present our variation on the theme at the forthcoming
112th AES Conference in Munich... We plan to go there with a car for doing
listening tests (collecting blind questionnaires) and comparing different
approaches for the surround reproduction inside the car compartment.
Bye!

Angelo Farina

----- Original Message -----
From: "K. K. Proffitt" <***@jamsync.com>
To: <***@music.vt.edu>
Sent: Friday, January 25, 2002 10:20 PM
Subject: Re: [Sursound] Re: Pop PRojects

Post by K. K. Proffitt
Most of the "surround sound" in automobiles now it being touted by Harman. This
involves upmixing with Logic 7 and is less than satisfactory for much program
material, especially classical.
--
Regards,
K.K.Proffitt
chief audio engineer, JamSync, Nashville
http://www.jamsync.com

Post by Eberhard Sengpiel
I would think that this kind of product will at least in the beginning
define the market, especially when surround is installed routinely in autos.
Very interesting: is there really a beginning of surround sound now? -

in

Post by K. K. Proffitt

Post by Eberhard Sengpiel
cars?
I once was more optimistic.
Eberhard Sengpiel
http://www.sengpielaudio.com
_______________________________________________
Sursound mailing list
http://mail.music.vt.edu/mailman/listinfo/sursound

_______________________________________________
Sursound mailing list
http://mail.music.vt.edu/mailman/listinfo/sursound

[Kurt Albershardt]

--On Friday, January 25, 2002 12:48 PM -0800 Stephen Barncard

Post by Eberhard Sengpiel
I would think that this kind of product will at least in the beginning
define the market, especially when surround is installed routinely in autos.

Consider that most everyone has a four-speaker array in their auto these
days, while only what, maybe 5% have 4-5-6 at home?


It certainly is an interesting possibility, but som may times we have been
told "it's coming" that it falls on mostly deaf ears I think.

[Jeffrey Silberman - SurroundWorks(tm)]

----- Original Message -----
From: "Kurt Albershardt" <***@nv.net>
To: <***@music.vt.edu>
Sent: Friday, January 25, 2002 1:32 PM
Subject: Re: [Sursound] Re: Pop PRojects

Post by Kurt Albershardt
Consider that most everyone has a four-speaker array in their auto these
days, while only what, maybe 5% have 4-5-6 at home?
It certainly is an interesting possibility, but so many times we have been
told "it's coming" that it falls on mostly deaf ears I think.

Not mine.... ;^)

[Mobile webmaster]

Are you asking me to compare the results using AB or X/Y pairs of Omni,
cardio, or figure of 8? Why?

That is not relevant to this thread, and everyone knows the answers.

What we are trying to get at, is, what is the comparison off axis, so why
use them and how this is relevant to 1/ coincident or a 2/ delay corrected
recordings when non coincident technique is used.

GT

Post by Goran Finnberg
Best,
Goran Finnberg
The Mastering Room AB
Goteborg
Sweden

[Mobile webmaster]

Thank you
I wasn't interested in the behaviour of single mics, and the final sentence
you write is precisely why I asked, why use them then?

Here.......

Post by Mobile webmaster
The demands of rear information are surely completely different from the
front, especially in a surround situation- I mean we don't for instance

want

Post by Mobile webmaster
to reproduce the audience in the same way as the artist.

GT

Post by Mobile webmaster
More precisely, a Figure 8 is 2 back-to-back cardioids mixed equally with
one out of phase - and you can "make" one just this way. Singly, a mic

with

Post by Mobile webmaster
this pattern can be made precise, which explains its reputation for being
"uncolored," is highly directional in attentuating sides, but requires EQ

of

Post by Mobile webmaster
its lows.

An orthogonal pair (Blumlein or B-format) Figure 8s combine for

Post by Mobile webmaster
omnidirectional energy distribution, which for recordists means a natural
but uncontrollable stage + hall balance.
Robin

Post by Mobile webmaster
Figure of 8 is basically 2 back to back omnis.

In this config it is normal not to have coloration, but not much
directivity.
The directivity is produced by the rear part of the 8 information derived
from 2 or more.
Figure of 8 are symmetric in their characteristics which means the front

and

Post by Mobile webmaster
rear sensitivities are equal.
We use another mic array or pair for that and it is not in the same spot.
(negative delay is introduced for distance compensation)
That is why we like either 2 dissimular seperate capsules, with phase
inversion or hypo characteristic (wide oval omni).
GT
Any good?

Post by Mobile webmaster

Post by Mobile webmaster
Why do people want to use figure 8s, is it because of Gerzon?

Some of us _like_ the sound of figure-8 microphones, both for their lack

of

Post by Mobile webmaster

Post by Mobile webmaster
off-axis coloration in comparison to most directional mics and their

ability

Post by Mobile webmaster
to capture room sound.

[Richard G. Elen]

Although the SFM has its limitations (but do check the latest models,
they are much quieter than the old Calrec ones), the big advantage it
has in my mind is coincidence - both the inherent physical closeness of
the capsules in the tetrahedral array and in the provision of electronic
compensation in the control unit - which was always a major factor,
being into localization as I am.

Although I have tried the B&K/Schoeps omni+crossed figure-8 combination
as implemented by Halliday at Nimbus, I never found the localization as
good, though the sound was better than the Calrec MkIII I was using at
the time (yes, this is a while ago). (I am assuming that Halliday
included some coincidence compensation in the "black box" which I didn't
have access to, but even so...). I would note incidentally that Nimbus
were only limited to recording on their own premises in the early days:
later on they made recordings all over the place, although the on-site
concert hall was of course used frequently once it became available.

The SFM has always been reliable and predictable for me, although the
older units with which I am most familiar did not have the best noise
figures.

I would keep your eyes on Soundfield Research. At Surround 2001 I was
lucky enough to have an extended discussion with one Pieter
Schillebeeckx, a new guy there who came from the group doing Ambisonics
at Derby. He is intent on taking the Ambisonic possibilities of the
system seriously (they were traditionally rather downplayed in the past
in favor of stereo flexibility). I think we might see some cool things
from them in the months to come.

--Richard E

[Mobile webmaster]

Sounds great!

A case of big is beautiful,
would love to have been there.......

Sound like this is the way things are going to go.

GT

I know there's some PR hype here, but still interesting...
sqb



Live at the Blue Note:
Chick Corea and Friends in a Series of High-Def Recordings
On December 23rd, an extraordinary musical experiment concluded at
the storied Blue Note jazz club in New York's Greenwich Village.
Chick Corea, one of the major jazz pianists to emerge in the past
thirty years, wound up a three-week stint during which he played with
nine different line-ups.

An equally extraordinary audio experiment also concluded. For the
first time anywhere - live or in a studio - an audio production team
recorded in 16-track Direct Streaming Digital (DSD), the recording,
editing, and playback technology behind the Super Audio Compact Disc
(SACD). Among the shifting line-up of microphones used over the
course of three weeks of live recording, three DPA units played
crucial roles - the 4041-T omni tube mic (part of a DPA 3532-T A-B
stereo tube mic kit, available to the recording team), and a pair of
4021 Compact cardioid mics. The 4041-T was used mainly on the upright
bass, and the 4021's as a spaced pair for room mics.

Mr. Corea's various ensembles included duos with Bobby McFerrin and
the pianist Gonzalo Rubalcaba; a trio called "Now He Sings, Now He
Sobs" with Roy Haynes and Miroslav Vitous; a tribute to the late,
legendary be-bop pianist Bud Powell with Roy Haynes, Christian
McBride, Joshua Redman, and Terence Blanchard ; and Mr. Corea's
current group, Origin.

The audio team, underwritten by Phillips Electronics NV, was led by
producer Herbert Waltl, CEO and chief producer of Torrance, CA-based
Media Hyperium. Waltl, chief engineer Clark Germain, and assistant
engineer Ted White had to capture the live sound of these changing
groups as well as the impromptu performances of the many guest stars
who dropped by to join in the three-week musical celebration of Mr.
Corea's 60th birthday. Among the luminaries, each presenting a
unique acoustic challenge, were George Benson, Bela Fleck, Wallace
Rooney, Diana Reeves, Isaac Hayes, Paul Schaeffer, Sherry Allen,
Chaka Khan, and Doug E. Fresh.

To complicate matters further, a film crew was shooting every other
night. Produced by Jon and Peter Shapiro of Ideal Entertainment and
directed by David Niles of Colossalvision, the film will ultimately
result in a two-hour documentary and a companion DVD along with a
two-disc, hybrid SACD set in 5.1 Surround Sound (playable on any CD
or DVD player, as well as an SACD player).

"Our goal was to reproduce the experience of these performances in
the highest fidelity possible," says Waltl. "Every night there were
magical moments and our job was to capture them - for the recording
and for the film. We have so many great performances on tape, that we
are discussing the opportunity to release additional titles, possibly
a complete box set of nine discs, one disc for each line-up."

Pioneering the first 16-track DSD recording required some ingenuity.
Swiss-based Merging Technologies provided their PYRAMIX software, and
designed a system to coordinate two 8-track DSD systems, creating a
virtual 16-track machine.

"To my knowledge no one has ever locked together two 8-track DSD
machines in this way," says Germain. "We had two separate computers,
one for each 8-track machine, driven by the PYRAMIX software."

The live setting presented unique challenges that went beyond
audience noise. The stage of the Blue Note is small and on most
nights it was crowded with musicians and instruments. "I had a
conversation with Chick before starting this project," says chief
engineer, Germain, "and he explained to me that, if possible, he
wanted to have the piano on full stick. He also said that given the
size constraints of the stage at the Blue Note and the fact that they
would be filming the event, he didn't want to use any baffling
between the instruments. Given these preconditions, I knew the
microphones would play an extremely important part of the recording
process."
Waltl and Germain chose the DPA 4041-T omni tube mic for the upright
bass, an instrument notoriously difficult to mike and record in a
live ensemble setting.

"The 4041-T provides a much fuller frequency response than other
mikes," says Germain. "And it performed exceptionally well on the
bass here."

Germain chose the tube-bodied model, vs. the solid state 4041-S.
"I've always been a big fan of older tube mics," he says. "I've
used this model on pianos and other instruments in the studio and
like it so much that I haven't gotten around to comparing it with the
solid state version."

For miking the room, the team chose two DPA Type 4021 compacts, the
world's smallest studio quality cardioid condenser microphone. In
addition to the sound quality of the 4021, produced by the same type
of cartridge as the full-sized 4011, its small size - 35 mm by 19 mm
- was ideal for a film setting that required the fewest possible
visual obstructions.

"The compact size of the 4021's and the bendable SM4000 Suspension
Mount proved valuable when it came to placing the room mics," says
White. "Clark was able to use the 'cork screw' end of the mounting
system to secure the microphones to the drop ceiling, which is made
of a very pliable and porous material. It was quite easy to screw the
mount to the ceiling in such a way that did not cause any damage to
the ceiling or the microphone. The result was an exact and very low
profile placement, which was also unobtrusive to the video crew."

With equipment arriving from Los Angeles, New York, the Netherlands,
and Switzerland, the team had only one day to set up before the first
performance.

[Mobile webmaster]

Is this worth it?
FYI

The first phrase that French learn to say in English is according to legend
"my taylor is rich"

(There's no secret,- beamers, are not my flavour, happiness is badged
"cosworth"
racist or common sense, as BMW copied their technology?)

Spelling???

As for the mic thread today, as Bob Cain demonstrated is most interesting.
If you use 2 or 4 mics mixed with figure of 8s, you get suprising results.

So why use them?

??

Post by seva

Post by Goran Finnberg

Post by Mobile webmaster
Figure of 8 is basically 2 back to back omnis.

Really???

hey, let's just ask taylor, the rich guy!
he's probably smart too, and can spell!
and he's probably not racist!

[Mobile webmaster]

You forgot the reflections from the hall, this is unlikely to cause phase
cancellation as you suggest.

More a chaotic stage and hall balance as suggested.

(>Controls the stage + hall balance very well in my experience.)

We are interested here in surround not in stereo techniques.

GT

Post by Goran Finnberg

Post by Robin Miller, Filmaker
An orthogonal pair (Blumlein or B-format) Figure 8s combine for
omnidirectional energy distribution, which for recordists means a natural
but uncontrollable stage + hall balance.

Which is simply not true at all since the back of the fig-eight is out
of phase with the front so for random incidence we would see part
cancellation of the ambience instead as compared to an omni.

Post by Robin Miller, Filmaker
omnidirectional energy distribution

And what will the pressure gradient loss at LF do to the energy
distribution where the phase shift acting on the membrane will be at its
weakest force?

Post by Robin Miller, Filmaker
but uncontrollable stage + hall balance.

In what way?
It is a simple matter to go out and change the mic placement in relation
to the stage to control this.
Controls the stage + hall balance very well in my experience.
--
Best,
Goran Finnberg
The Mastering Room AB
Goteborg
Sweden

[Goran Finnberg]

Post by Mobile webmaster
You forgot the reflections from the hall, this is unlikely to cause phase
cancellation as you suggest.

The cancellations is how the mic works not in the reflections of the
hall.

Whether you use one two three whatever fig-8 mics does not change the
working principle, no?

Post by Mobile webmaster
We are interested here in surround not in stereo techniques.

Then tell that to the original contributor who specifically talked about
Blumlein.

:-)

[Scott Kent]

Unlike most of you everything I say is hearsay, plus I am a lazy speller
excuse me please. In defense, great insight can come from
innocence/ignorance.

Has anyone given thought to "Earthworks"(there capsule are realy small like
1cm diameter or so. If I had the $$ I would take 6 cardiod earthworks
capsules together for the x,y,z. Then I would AD 24/192 the Mic level signal
and process this with DSP. I think this is the only way to go. One could do
a quick calibration right before they start.

I was also woundering if anyone has tried similar with the SF MKIV. I hate
that they make you use there hardware. I want to automate the paning and
rotating.....


Just a thought....

As fare as spaced OMNIs and Directionality Try The HOLOPHONE????

Post by Culann mac Caba
Subject: Re: [Sursound] ambisonic microphone techniques
Date: Fri, 25 Jan 2002 20:00:38 +0100
Is this worth it?
FYI
The first phrase that French learn to say in English is according to legend
"my taylor is rich"
(There's no secret,- beamers, are not my flavour, happiness is badged
"cosworth"
racist or common sense, as BMW copied their technology?)
Spelling???
As for the mic thread today, as Bob Cain demonstrated is most interesting.
If you use 2 or 4 mics mixed with figure of 8s, you get suprising results.
So why use them?
??

Post by seva

Post by Goran Finnberg

Post by Mobile webmaster
Figure of 8 is basically 2 back to back omnis.

Really???

hey, let's just ask taylor, the rich guy!
he's probably smart too, and can spell!
and he's probably not racist!

_______________________________________________
Sursound mailing list
http://mail.music.vt.edu/mailman/listinfo/sursound

_________________________________________________________________
Chat with friends online, try MSN Messenger: http://messenger.msn.com

[Kurt Albershardt]

--On Friday, January 25, 2002 8:30 PM +0000 Scott Kent

Post by Scott Kent
Has anyone given thought to "Earthworks"(there capsule are realy small like
1cm diameter or so. If I had the $$ I would take 6 cardiod earthworks
capsules together for the x,y,z. Then I would AD 24/192 the Mic level
signal and process this with DSP. I think this is the only way to go. One
could do a quick calibration right before they start.

One could do the same with miniature mics from Schoeps or DPA I would think.

Post by Scott Kent
I was also woundering if anyone has tried similar with the SF MKIV. I hate
that they make you use there hardware. I want to automate the paning and
rotating.....

Why doesn't the Soundfield have an upcharge option available for premium
capsules? I'm sure they could work something out with DPA, Schoeps, Milab or
a similar manufacturer and then be free to focus on their core competencies.
I'll bet a lot of their customers or potential customers would spend the
extra $$.

[Jeffrey Silberman - SurroundWorks(tm)]

----- Original Message -----
From: "Kurt Albershardt" <***@nv.net>
To: <***@music.vt.edu>
Sent: Friday, January 25, 2002 1:00 PM
Subject: Re: [Sursound] ambisonic microphone techniques

Post by Kurt Albershardt
Soundfield have an upcharge option available for premium
capsules? I'm sure they could work something out with DPA, Schoeps, Milab or
a similar manufacturer and then be free to focus on their core

competencies.

Post by Kurt Albershardt
I'll bet a lot of their customers or potential customers would spend the
extra $$.

I am not aware of such an option; however, the US importer of SoundField is
a subsciber to this list. Perhaps, he can apprise us differently or shed
light on digital developments.

[John A. Leonard]

Post by Mobile webmaster
Taking some bits of this thread and criticisms adds up to a picture which I
have strong gut feelings about. ('scuse the pun)

To avoid the long quoting session, but to answer some of the points:

The question was - why do people use Soundfield microphones?

I gave _my_ answers, so no generalisation. I also qualified by YMMV, which
yours obviously does.

My current ST250 has just been factory modified and re-capsuled and is now
plenty quiet enough for _my_ needs, thanks very much.

The live music recordings that I've done have been extremely well received
by the musicians who were playing and others who have heard them, and I like
the way that they sound.

Some of the earliest recording made with my ST250 still sound stunning today
- immensely detailed with excellent imaging. I'm certainly not disappointed.

If someone will point me in the direction of an alternative that can be used
in the many and varied ways that I use my ST250, doesn't cost twice the
price, doesn't require that I spend longer setting up the system than I do
recording what I need (and we're talking about time equalling money in
almost all these situations) doesn't require me to transport enormous
amounts of mains-powered kit plus inverters and/or generators to the remote
locations that I usually have to record in and will get me good results in
next-to-impossible locations, then I'll certainly consider it.

Please understand that not everybody who uses ambisonic techniques is
involved in music recording in controlled circumstances. You may not care
about what I do, but the people who employ me certainly do. If you like, you
can come along to my next set of sessions, which are going to be in the
swamps around New Orleans, in the middle of the Mardi Gras celebrations and
in and around various dubious bits of Manhattan. I know that the ST250 will
give me the results I want, but I won't get a chance to do anything other
than dive in, start recording and dive out again.

Regards,



John A Leonard
Aura Sound Design Ltd.
23 Charlotte Road
London EC2A 3PB
Tel: [phone] Fax: [phone]
http://www.aurasound.co.uk

The book is out!
http://www.aurasound.co.uk/files/theatresound.html

[Jeffrey Silberman - SurroundWorks(tm)]

----- Original Message -----
From: "John A. Leonard" <***@btinternet.com>
To: <***@music.vt.edu>
Sent: Friday, January 25, 2002 3:22 PM
Subject: Re: [Sursound] ambisonic microphone techniques

Post by John A. Leonard
My current ST250 has just been factory modified and re-capsuled and is now
plenty quiet enough for _my_ needs, thanks very much.

When was your ST 250 purchased if you do not mind me asking (was it during
AMS's ownership of the company?) I had my ST-250 re-capsuled (about 8 years
old) when I noticed it becoming noisier and was informed that the capsules
during the AMS tenure were inferior to the current ones. Incidentally, you
stated that yours had been "modified" - in what way? For most live/ field
applications the St-250 is sufficiently quiet, but in low noise
environments, one hears hiss.

Post by John A. Leonard
The live music recordings that I've done have been extremely well received
by the musicians who were playing and others who have heard them, and I like
the way that they sound.

I like the timbre of the St-250 as well; I prefer its timbre all the more
ambisonically decoded.

Post by John A. Leonard
Some of the earliest recording made with my ST250 still sound stunning today
- immensely detailed with excellent imaging. I'm certainly not

disappointed.

Imaging is the SoundField's forte.

Post by John A. Leonard
If someone will point me in the direction of an alternative that can be used
in the many and varied ways that I use my ST250, doesn't cost twice the
price, doesn't require that I spend longer setting up the system than I do
recording what I need (and we're talking about time equalling money in
almost all these situations) doesn't require me to transport enormous
amounts of mains-powered kit plus inverters and/or generators to the remote
locations that I usually have to record in and will get me good results in
next-to-impossible locations, then I'll certainly consider it.

The St-250 certainly is convenient- no denying that.

Post by John A. Leonard
Please understand that not everybody who uses ambisonic techniques is
involved in music recording in controlled circumstances. You may not care
about what I do, but the people who employ me certainly do. If you like, you
can come along to my next set of sessions, which are going to be in the
swamps around New Orleans, in the middle of the Mardi Gras celebrations and
in and around various dubious bits of Manhattan. I know that the ST250 will
give me the results I want, but I won't get a chance to do anything other
than dive in, start recording and dive out again.

Do you record in B-Format? Is there a B-Format SFX library?

[Richard Elen]

I would think it would be quite difficult to do. The compensation must
be quite different and I bet it would take a lot of tweaking.
--Richard E

On Friday, January 25, 2002, at 02:30 PM, Jeffrey Silberman -

Post by Kurt Albershardt
Soundfield have an upcharge option available for premium
capsules? I'm sure they could work something out with DPA, Schoeps,
Milab

or

Post by Kurt Albershardt
a similar manufacturer and then be free to focus on their core

competencies.

Post by Kurt Albershardt
I'll bet a lot of their customers or potential customers would spend the
extra $$.

[G***@aol.com]

Hi John,

You've hit on a couple very good points which apply regardless of the mic
used.

One, "I'm certainly not disappointed." While I appreciate hearing the
perspectives of others that make mic decisions, this one is quite important.
You have to realize your own budget, capabilities, expectations, and put it
in to context with all the other equipment the mic will be feeding. (No point
having a $20,000 mic feeding a home camcorder.)

Second, and I think this is most important, "The live music recordings that
I've done have been extremely well received by the musicians who were playing
and others who have heard them, ..." So often we overlook who our audience
is. Those who pays the bills.

While I prefer the sound of certain mics over others, in the end it comes
down to many factors that not only include my time and cost of production,
but whether it meets or exceed the customer's expectations. For me the
validation of using the SoundField Mark V (supplemented with other mics) was
when the conductors and musicians told me they liked what they heard and they
specifically asked for me to do subsequent recordings of their work. Maybe
someday I'll advance another tier. ;~)

-- Gary Reece

Post by Mobile webmaster
Taking some bits of this thread and criticisms adds up to a picture which I
have strong gut feelings about. ('scuse the pun)

To avoid the long quoting session, but to answer some of the points:

The question was - why do people use Soundfield microphones?

...

The live music recordings that I've done have been extremely well received
by the musicians who were playing and others who have heard them, and I like
the way that they sound.

Some of the earliest recording made with my ST250 still sound stunning today
- immensely detailed with excellent imaging. I'm certainly not disappointed.

...

[Scott Kent]

I second That.


Jeffrey Silberman said;

Post by Jeffrey Silberman - SurroundWorks(tm)
What is the prospect of the "bsystem" being made commercially available on
the TC6000 platform?
_______________________________________________
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_________________________________________________________________
Join the world’s largest e-mail service with MSN Hotmail.
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[Culann mac Caba]

Jeffrey/Scott,

Our view of the basic technology is broader than just pro audio - the
bSystem project is also looking at 3G apps, for example. As for the S6000 -
we're using it because of its very high quality spec (we do also run this
stuff on other platforms); re. commecial prospects of something like
bSystem, it is not for me alone to consider...

Culann
--
Culann mac Caba
Cuan.

----- Original Message -----
From: Scott Kent <***@hotmail.com>
To: <***@music.vt.edu>
Sent: Saturday, January 26, 2002 4:39 AM
Subject: Re: [Sursound] ambisonic microphone techniques

Post by Scott Kent
I second That.
Jeffrey Silberman said;

Post by Jeffrey Silberman - SurroundWorks(tm)
What is the prospect of the "bsystem" being made commercially available on
the TC6000 platform?
_______________________________________________
Sursound mailing list
http://mail.music.vt.edu/mailman/listinfo/sursound

_________________________________________________________________
Join the world's largest e-mail service with MSN Hotmail.
http://www.hotmail.com
_______________________________________________
Sursound mailing list
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[John A. Leonard]

on 26/1/02 12:18 AM, Jeffrey Silberman - SurroundWorks(tm) at

Post by Jeffrey Silberman - SurroundWorks(tm)
When was your ST 250 purchased if you do not mind me asking (was it during
AMS's ownership of the company?)

Ah yes - well, the serial number of the original mic was 006, I seem to
remember: I went through quite a few in the early days and yes, it was AMS.

Post by Jeffrey Silberman - SurroundWorks(tm)
I had my ST-250 re-capsuled (about 8 years
old) when I noticed it becoming noisier and was informed that the capsules
during the AMS tenure were inferior to the current ones.

Same here: I also believe that I posses the prototype of the current
polycarbonate array-holder. Soundfield Research carried out the mod at no
cost on the understanding that I'd pay for any further work if it all went
horribly wrong, which it didn't. They inherited my mic as a repair/service
when AMS sold them the manufacturing rights and my ST250 was included in the
pile of stuff that was delivered to them. It took me a while to find out
where it had gone ;-)

I've also got the prototype Rycote set-up, which could do with replacing -
it's seen a lot of action.

Post by Jeffrey Silberman - SurroundWorks(tm)
Incidentally, you
stated that yours had been "modified" - in what way? For most live/ field
applications the St-250 is sufficiently quiet, but in low noise
environments, one hears hiss.

I've had a later model pre-amp board fitted, which is so much quieter than
the old one.

Regards,
--
John A Leonard
Aura Sound Design Ltd.
23 Charlotte Road
London EC2A 3PB
Tel: [phone] Fax: [phone]
http://www.aurasound.co.uk

The book is out!
http://www.aurasound.co.uk/files/theatresound.html

[Marco Olivotto]

Post by Jeffrey Silberman - SurroundWorks(tm)
I had my ST-250 re-capsuled (about 8 years
old) when I noticed it becoming noisier and was informed that the capsules
during the AMS tenure were inferior to the current ones.

Just a small remark: I have a very recent Soundfield MKV. Anyone who
claims it's noisy is, ahem, cheating. I don't say there aren't more silent
mics if you compare them to the MKV in a very controlled environment like,
say, an anechoic chamber :-). But for any kind of application, the unit is
silent enough. Works perfectly for me, from chamber to choral music, from
symphonic to ambient recording.

Regards,

Marco
---
Marco Olivotto
Sonica Studios
16 Via dell'Abetone
38068 ROVERETO (TN)
ITALY
Tel/Fax: [phone]
---
Visit www.sonicastudios.com - finally updated, up and running!

[Angelo Farina]

The MKV is not noisy. Some ST-250 are noisy, but it depends a lot on the
power supply.
With partially discherged batteries, it becomes quite noisy.
With clean mains supply, my one is as quite as my previous MK-V. The
problems which I got with the MK-V were mainly due to its impossibility to
be calibrated properly. All those knobs, two independent gain pots, and the
inter-capsule calibration is made (internally to the control unit) through 8
horrible screwable pots (not multi-turn, and absolutely unreliable).
The very good thing of the ST-250 is that, in B-format mode, You do not have
any pot in the signal path, everything is fixed!
Bye!

Angelo Farina
----- Original Message -----
From: "Marco Olivotto" <***@sonicastudios.com>
To: <***@music.vt.edu>
Sent: Saturday, January 26, 2002 3:41 PM
Subject: Re: [Sursound] ambisonic microphone techniques

Post by Marco Olivotto

Post by Jeffrey Silberman - SurroundWorks(tm)
I had my ST-250 re-capsuled (about 8 years
old) when I noticed it becoming noisier and was informed that the capsules
during the AMS tenure were inferior to the current ones.

Just a small remark: I have a very recent Soundfield MKV. Anyone who
claims it's noisy is, ahem, cheating. I don't say there aren't more silent
mics if you compare them to the MKV in a very controlled environment like,
say, an anechoic chamber :-). But for any kind of application, the unit is
silent enough. Works perfectly for me, from chamber to choral music, from
symphonic to ambient recording.
Regards,
Marco
---
Marco Olivotto
Sonica Studios
16 Via dell'Abetone
38068 ROVERETO (TN)
ITALY
Tel/Fax: [phone]
---
Visit www.sonicastudios.com - finally updated, up and running!

[Jeffrey Silberman - SurroundWorks(tm)]

----- Original Message -----
From: Marco Olivotto
To: ***@music.vt.edu
Sent: Saturday, January 26, 2002 6:41 AM
Subject: Re: [Sursound] ambisonic microphone techniques

Just a small remark: I have a very recent Soundfield MKV. Anyone who
claims it's noisy is, ahem, cheating. I don't say there aren't more silent
mics if you compare them to the MKV in a very controlled environment like,
say, an anechoic chamber :-). But for any kind of application, the unit is
silent enough. Works perfectly for me, from chamber to choral music, from
symphonic to ambient recording.
**************************************************************

I am not sure I catch your drift re: cheating. Be that as it may, I have
previously acknowledged that for most real-world applications the St-250's
self-noise is masked by ambience. However, there have been ocassions where
I have recorded in subterranneum spaces and compared to a B-Format array of
Sennheiser MKH capsules, the ST-250 was significantly noisier. Who was it
that said that "silence is the loudest sound" (Cage?). When one listens in
surround, black, cold silence is mandatory, for multichannel audio
perceptually unmasks noise/hiss much more so than stereophony. Hiss
destroys the illusion of "being there."

[Eero Aro]

I have a very recent Soundfield MKV. Anyone who claims it's noisy is,
ahem, cheating.

Count me in. It's noisy.

. But for any kind of application, the unit is silent enough.

"Any" application?" Silent "enough"? For radio drama the self noise of the
SFM is too high,
both for dialogue and ambient sound effects. I have both 250 and MK V in my
use.

How to record silence? - Not with a Soundfield, anyway.

Jeff hit the point, masking. If you record an ambience where there aren't
too many sound
sources, just some birds or a frog, maybe quiet wind, you will hear the
right things in their
right directions, but in multichannel reproduction the noise comes from all
directions and
that is disturbing.

I have noticed that if the polarizing voltage in the 250 gets low, not only
the noise gets higher,
but also the directional patterns go wrong.

It's good to keep the 250 connected to mains for at least two hours (I
leave it overnight) before
going out to record using batteries, to charge the electrolyte capasitors
to full voltage. It takes
a long time to do that from the batteries. Also, unplug the headphones from
the 250 box.

Eero Aro
***@dlc.fi

[Kurt Albershardt]

Post by Eero Aro
I have noticed that if the polarizing voltage in the 250 gets low, not only
the noise gets higher, but also the directional patterns go wrong.
It's good to keep the 250 connected to mains for at least two hours (I
leave it overnight) before going out to record using batteries, to charge
the electrolyte capasitors to full voltage. It takes a long time to do that
from the batteries. Also, unplug the headphones from the 250 box.

What kind of polarizing voltage/current does it need? It should be a fairly
simple matter to rig up a switching supply and a small deep-cycle for the
task if the original supply is not up to it.

[John A. Leonard]

on 26/1/02 12:18 AM, Jeffrey Silberman - SurroundWorks(tm) at

Post by Jeffrey Silberman - SurroundWorks(tm)
Do you record in B-Format?

Just starting to do direct-to hard drive location work in B-Format. ST250,
Metric Halo MIO and DP3.

Post by Jeffrey Silberman - SurroundWorks(tm)
Is there a B-Format SFX library?

Watch this space!

Regards,
--
John A Leonard
Aura Sound Design Ltd.
23 Charlotte Road
London EC2A 3PB
Tel: [phone] Fax: [phone]
http://www.aurasound.co.uk

The book is out!
http://www.aurasound.co.uk/files/theatresound.html

[DG Malham]

Being REALLY pedantic about it ;-) there are only two fundamental polar
patterns from which all others are derived, at least amongst ordinary,
first order microphones, figure-8 (velocity sensitive) and
omnidirectional (pressure sensitive).

Dave

Post by Robin Miller, Filmaker
More precisely, a Figure 8 is 2 back-to-back cardioids mixed equally with
one out of phase - and you can "make" one just this way. Singly, a mic with
this pattern can be made precise, which explains its reputation for being
"uncolored," is highly directional in attentuating sides, but requires EQ of
its lows. An orthogonal pair (Blumlein or B-format) Figure 8s combine for
omnidirectional energy distribution, which for recordists means a natural
but uncontrollable stage + hall balance.
Robin

Post by Mobile webmaster
Figure of 8 is basically 2 back to back omnis.

In this config it is normal not to have coloration, but not much
directivity.
The directivity is produced by the rear part of the 8 information derived
from 2 or more.
Figure of 8 are symmetric in their characteristics which means the front and
rear sensitivities are equal.
The demands of rear information are surely completely different from the
front, especially in a surround situation- I mean we don't for instance want
to reproduce the audience in the same way as the artist.
We use another mic array or pair for that and it is not in the same spot.
(negative delay is introduced for distance compensation)
That is why we like either 2 dissimular seperate capsules, with phase
inversion or hypo characteristic (wide oval omni).
GT
Any good?

Post by Mobile webmaster

Post by Mobile webmaster
Why do people want to use figure 8s, is it because of Gerzon?

Some of us _like_ the sound of figure-8 microphones, both for their lack of
off-axis coloration in comparison to most directional mics and their

ability

Post by Mobile webmaster
to capture room sound.

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[Scott Kent]

Post by Jeffrey Silberman - SurroundWorks(tm)
Subject: RE: [Sursound] ambisonic microphone techniques
Date: Mon, 28 Jan 2002 09:22:06 +0000 (GMT)
Being REALLY pedantic about it ;-) there are only two fundamental polar
patterns from which all others are derived, at least amongst ordinary,
first order microphones, figure-8 (velocity sensitive) and
omnidirectional (pressure sensitive).
Dave

Thanks,
That clicked the light bulb on in my head.
I see what you all are talking about when you sugest pressure & velocity.
Omni has the sealed chamber of which the air gets compressed and rarefracted
relative to the foce place on the outside of the diaphram(Air Pressure).
Where as the figure of 8 is realy just a diaphram flapping in the breeze
where the diaphram moves relative to the pressure difference between the +
and - side of the diaphram. So if you uniformly increase the airpressure it
will depress the omni diaphram but will not affect the fig.8's diaphram as
the pressure difference is 0. This is why fig.8s have that pattern, because
when the velocity vector is parallel to the diaphram the presure difference
is 0.
So when setting up an array you are basicly trying to create an array of
sensors that can be used to triangulate the velocity vector. So in designing
an array you must take into consideration our audible spectrum and our
directional sensitivity threwout the spectrum. Once one knows this
information, they can find capsules that match our directional sensitivity
vs. frequecny pattern.
So now I have an array of sensors that triangulates the velocity vector of a
soundwave with a level of accuracy that closely matches that of humans over
our audible spectrum. If you have an arrangement like S.F. then the part of
the spectrum that has 0 directionality will be seen on all sensors.
Is this a good generalization???
Am I way out or am I grasping the concept.




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[Scott Kent]

Show Off. |-{;-P

Post by Angelo Farina
Subject: Re: [Sursound] Re: Pop PRojects
Date: Fri, 25 Jan 2002 14:12:41 -0800
----- Original Message -----
Sent: Friday, January 25, 2002 1:32 PM
Subject: Re: [Sursound] Re: Pop PRojects

Post by Kurt Albershardt
Consider that most everyone has a four-speaker array in their auto these
days, while only what, maybe 5% have 4-5-6 at home?
It certainly is an interesting possibility, but so many times we have

been

Post by Kurt Albershardt
told "it's coming" that it falls on mostly deaf ears I think.

Not mine.... ;^)

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