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Updateable list of "Ambisonic-legal" mics? Modular Synthesizers
Old 17th July 2017
  #1
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Thread Starter
Updateable list of "Ambisonic-legal" mics?

I'd like to have a sticky for this subforum that lists the mics available that can produce correct Ambisonic recordings (including all-in-one units mic+recorder)?

I know of/have used:

--Tetra mic (Core Audio)

--Ambeo (Sennheiser)

--Soundfield (2 or 3 models?)

--Brahma (standalone and attached to a Zoom H-?)

--bespoke arrays of mono mics

what else?
Old 18th July 2017
  #2
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PatrickFaith's Avatar
 

I use 4 schoeps ccm41's, but I'd say 90% of the time it's a single schoeps cmit 5u object that is rendered into a immersive format (i.e. a whole lot of other single x,y,z objects tracks and the computer audio renderer goes to which ever format is needed). The cmit 5u is used with the ccm41 because it mixes perfectly(i.e. it's real hard to tell the difference between a ccm41 and a cmit5u). This btw is not for music.
Old 18th September 2017
  #3
Gear Head
 

I'm looking at getting a larger diaphragm Brahma and think they might be the best bang/buck. Do you have any experiences with this mic? It has 25mm capsules.
Old 18th September 2017
  #4
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Current Soundfield mics are the SPS200( standalone mic that requires you to supply 4 channels of gain-matched preamp. A-format conversion to B-format and stereo/Surround in computer via software), ST-450 MKll (mic plus dedicated analog preamp/processor that
outputs B-Format plus stereo decode at line level plus headphone output. The stereo decode (line level and headphone)
can be adjusted continuously to any pattern from omni to fig 8 with stereo
angle continuously variable between 0 and 180 deg. The B-format can also be decoded with computer software to stereo/ surround. The highest quality
(quietest, best phase accuracy) are DSf-1 (and broadcast oriented DSF-B). Their dedicated preamp/processor uses digital processing that helps to give its superior
phase accuracy and quietness. The DSF-1 outputs B-format and a stereo decode
in AES digital plus a headphone output.
The preamp/processor can decode to stereo with the same flexibility as the ST450 plus you can virtually rotate the mic.
Unlike most AF condensers that are susceptible to popping noises in humid
environments, the ST450 and DSF mics
are relatively immune as they both have
heaters within the microphone.
I own a DSF-1 and the first version of the ST450 and am happy to answer questions.
Old 19th September 2017
  #5
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PatrickFaith's Avatar
 

Quote:
Originally Posted by Folkie View Post
Current Soundfield mics are the SPS200( standalone mic that requires you to supply 4 channels of gain-matched preamp. A-format conversion to B-format and stereo/Surround in computer via software), ST-450 MKll (mic plus dedicated analog preamp/processor that
outputs B-Format plus stereo decode at line level plus headphone output. The stereo decode (line level and headphone)
can be adjusted continuously to any pattern from omni to fig 8 with stereo
angle continuously variable between 0 and 180 deg. The B-format can also be decoded with computer software to stereo/ surround. The highest quality
(quietest, best phase accuracy) are DSf-1 (and broadcast oriented DSF-B). Their dedicated preamp/processor uses digital processing that helps to give its superior
phase accuracy and quietness. The DSF-1 outputs B-format and a stereo decode
in AES digital plus a headphone output.
The preamp/processor can decode to stereo with the same flexibility as the ST450 plus you can virtually rotate the mic.
Unlike most AF condensers that are susceptible to popping noises in humid
environments, the ST450 and DSF mics
are relatively immune as they both have
heaters within the microphone.
I own a DSF-1 and the first version of the ST450 and am happy to answer questions.
I just love the idea of having the gain-matched preamps, there is so much that can be done when everything is perfectly balanced. If you have some time, I'd like to understand the "zoom" functions that are available. For example, most of the time I can't place the surround sound mic where I'd like to, it's often about 8 feet from what I'd think would be the optimal listening position (i.e. let's say there was a discussion and I want the mic to be situated in the middle of the discussion, but often I need to put it out of the way a bit so it doesn't interfere with camera's filming).

I really need to also download the AAX plugin, it all just looks like great stuff, I'm kind of gear lusting over the SPS200.
Old 19th September 2017
  #6
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Quote:
Originally Posted by PatrickFaith View Post
I just love the idea of having the gain-matched preamps, there is so much that can be done when everything is perfectly balanced. If you have some time, I'd like to understand the "zoom" functions that are available. For example, most of the time I can't place the surround sound mic where I'd like to, it's often about 8 feet from what I'd think would be the optimal listening position (i.e. let's say there was a discussion and I want the mic to be situated in the middle of the discussion, but often I need to put it out of the way a bit so it doesn't interfere with camera's filming).

I really need to also download the AAX plugin, it all just looks like great stuff, I'm kind of gear lusting over the SPS200.
As to gain-matched preamps, they are necessary for proper decoding of any Ambisonic mic.
The ST450 and DSF-1 each come with a dedicated preamp/processor box.
BUT the SPS200 is a mic only. You have
to provide your own preamps.

As to the "Zoom" function it helps
with narrowing the focus BUT it isn't a substitute for being close enough. Even with the expensive Harpex B decoding software decoded in "shotgun" mode it is limited in reach. It's not the same as using a real shotgun mic.

To position a Soundfield (or other Ambisonic mic) properly you need to
monitor an omni decode and locate it to
get the proper direct to reverberant balance and then you can open it up
to a stereo pattern of choice.
Old 26th October 2017
  #7
Gear Maniac
 

- mh acoustics Eigenmike

- Zylia ZM-1

- Zoom H2n
Old 26th October 2017
  #8
Lives for gear
 

Quote:
Originally Posted by philper View Post
I know of/have used:

--Tetra mic (Core Audio)
I seem to recall Core Audio (or whatever they're called) showing a brand new mic at AES, I think it had 8 capsules and was called "octo" or something.
Old 26th October 2017
  #9
Gear Maniac
 

Yes, it's a 2nd order mic, so nine B-Format channels.
Old 21st December 2017
  #10
Here for the gear
 

Twirling



There is also the Twirling 720 recorder with mic.
Old 28th February 2018
  #11
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Last edited by Gusss; 28th February 2018 at 11:24 AM..
Old 5th March 2018
  #12
Gear Head
 

Quote:
Originally Posted by Gusss View Post
the gap between two capsules on each axis means there are some errors at high frequencies
Would bigger membranes or different material catch the higher frequencies better?
Old 5th March 2018
  #13
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Quote:
Originally Posted by mycall View Post
Would bigger membranes or different material catch the higher frequencies better?
I dont think so because its the speed of the capsule moving back and forth along each axis that defines the frequency. If I remember rightly the soundfield only has 3 capsules. If I remember rightly the tiny gap between the two capsules on each axis in the Velan means that frequencies with a wavelength of that length or smaller have errors (wavelengths the width of the gap or smaller). Its been a long time , Ill double check when I get a moment........
PS It worked really well !!
Old 5th March 2018
  #14
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Quote:
Originally Posted by Gusss View Post
I dont think so because its the speed of the capsule moving back and forth along each axis that defines the frequency. If I remember rightly the soundfield only has 3 capsules. If I remember rightly the tiny gap between the two capsules on each axis in the Velan means that frequencies with a wavelength of that length or smaller have errors (wavelengths the width of the gap or smaller). Its been a long time , Ill double check when I get a moment........
PS It worked really well !!
All of the Soundfield brand mics have
4 capsules. The newest (and highest
quality) Soundfield mic is the DSF-1/DSF-2) with phase accuracy to 15k.
Old 5th March 2018
  #15
Lives for gear
Quote:
Originally Posted by Folkie View Post
All of the Soundfield brand mics have
4 capsules. The newest (and highest
quality) Soundfield mic is the DSF-1/DSF-2) with phase accuracy to 15k.
Yes you're absolutley right - like I say its been a long time since I used ambisonics. A quick brush up shows that the 4 capsules in the Soundfield are the vertexes of a cube (8 vertixes) whereas in the Velan each pair of the three capsules is the X,Y, Z with the sum (or fraction thereof) being the W....
This looks liek a good resource :

A-format to B-format conversion

The summing for the axes in the soundfield appears to be this :

W' = FLU+FRD+BLD+BRU

X' = FLU+FRD-BLD-BRU

Y' = FLU-FRD+BLD-BRU

Z' = FLU-FRD-BLD+BRU

Whereas when I made the endoder for the Velan it was this :

Left + & - right = x
Front + & - Back = y
Top + & - bottom = z
All summed * 0.257 = w

Never used the bloody thing apart from once though !

Last edited by Gusss; 5th March 2018 at 09:57 AM..
Old 9th March 2018
  #16
Here for the gear
 

Now there is the Twirling 720 Lite, a microphone that turns your smartphone into an ambisonic recorder.

Twirling720 Lite
Old 30th May 2018
  #18
Here for the gear
 

Question Core OctoMic

Audio Rents now carries the Core OctoMic 2nd order ambisonic mic.

Anyone have any experience with it?
Old 31st May 2018
  #19
Gear Maniac
 

Bear in mind that the new Core Sound OctoMic is more "1st order and a half" than true 2nd order. The insufficient number of caps makes it impossible to derive a complete set of 2nd order spherical harmonics.

Already in 1973, Michael Gerzon found that a dodecahedron of (12) cardioid caps was necessary to have a complete set of 2nd order spherical harmonics. His old partner in crime, Peter Craven, proposed other models of 2nd and 3rd order mics.

AES E-Library >> Periphony: With-Height Sound Reproduction This paper is 45 years old: the fact that AES still ask $33 for it is beyond me...

https://iaem.at/ambisonics/symposium...tialsphmic.pdf

Last edited by Kewl; 31st May 2018 at 09:29 PM..
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