ambisonic microphones

[forumuser815440]

Hi there,

Lately I am seeing more and more surround mics on the market. Which I like because I've always wanted a soundfield but thought it was to expensive for the 3/4 times a year I use it. Now I am seeing mics between 999 and 1500 dollar. Which is 1/5 or so of the soundfield price.
To be exact these mics:
http://www.core-sound.com/TetraMic/1.php
http://www.recordingservices.net/microphone/MK012AM-Ambient-Specs.html

I have had pretty good results with other oktava's in the past so I was wondering if this is the "volkswagen among ambisonic mics".
I guess I can use software to make the B-Format into anything I want.

My question is this: who has anything to say about these mics or has another example of an ambisonic mic. Maybe one of the SOS writers can make an article about it: Ambisonic for the masses or something like that

[Bob Moose]

Hello,

If you absolutely want to record the vertical component (Z), the Core Sound should be only one for your budget. I guess it can be too noisy sometimes (because of the tiny size of the capsules).

But if WXY is sufficient, you can record to "horizontal B-Format" with 3 coincident microphones (one omni and two fig-8 microphones).

Alternatively, Double M/S (two cardioids + one fig-8) or Front-Left-Right-Back (4 cardioids) coincident recordings can be converted easily to horizontal B-Format.

In any case, both the omnis and the fig-8s should be single-diaphragm designs. Moreover, they should be small enough in order to get an acceptable coincidence. It is therefore quite difficult to find the right figure-of-eight microphone. Maybe a Beyerdynamic M 130, as 0VU recommended on this forum.

The 500-euro Line Audio QM12i can be used as a Front-Left-Right-Back microphone but I never tried it. There could be too much space between its capsules so you may want to calibrate them, like you do with the A-Format microphones (see Angelo Farina, "A-Format to B-Format conversion": http://pcfarina.eng.unipr.it/Public/B-format/A2B-conversion/A2B.htm).

You can have a look at these pages too:
http://www.radio.uqam.ca/ambisonic/
http://www.radio.uqam.ca/ambisonic/native_b.html

The only B-Format microphones I have used in practice are the Soundfield ST350, the Schoeps CCM Double M/S and a native horizontal B-Format array made of Schoeps CCMs. I used these microphones when testing some B-Format decoders I was programming at that moment. But I don't own any of them! (I am trying to find some "multi-purpose" fig-8s that I could use as part as a coincident surround array sometimes).

All the best,
-j

[Hugh Robjohns]

Ambisonics is as much to do with the decoder side of things as the microphone, and there are very, very few proper ambisonics decoders around these days.

Most people simply want horizontal surround sound, broadly compatible with a typical domestic 5.1 system, and horizontal B-format or MSM systems, as Bob has mentioned, are perfectly appropriate (and generally cheaper) solutions for that.

There is no doubt that the SoundField is the daddy in all this, and the latest digital models -- the DSF-1 and DSF-2 -- finally realise the true potential of the format. The older analogue models (Mark V, SPS422B, ST350 -- and their forebears), good though they were, tended to be noisy because of all the analogue signal processing involved in matrixing the A-format capsule's outputs.

Of the clones that are currently on the market, the Core Sound model is very compact, which is good from an imaging point of view, but the small capsules tend to be noisy again, and although the A-format re-coding is done digitally I found noise was an issue when I tried it out a couple of years agoi.

I've not tried the Oktava solution, but it looks bulky to me with large capsule spacings that will compomise imaging.

The other A-format option is SoundField's own SPS200 which is has tightly integrated capsules like the Core Audio, but uses larger high quality mic elements for better noise performance. The re-coding software is extremely good -- but it's well outside your price range, I'm afraid.

Horizontal B-format arrays using two fig-8s and an omni work well, especially if you can use small capsules like Schoeps or Sennheisers, and MSM (double MS) using two cardioids and a fig-8 also work extremely well for generating horizontal surround sound -- and the decoding is trivially simple.

Hugh

[Studio Support Gnome]

My Dad has the core sound , and seems very happy with it....

he knows a thing or two about ambisonics as well.

http://ambisonic.info/index.html

[ROLO46]

try M/S/M as budget ambisonic