If only two mics... ?

[ricardo]

BTW, there are some caveats about using the Calrec Soundfield Mk4 in Stereo due to my not actually using it for stereo until I left Calrec.

The most damning is that the Stereo output is out of phase. Mea culpa, mea culpa, mea maxima culpa

 

[thor.zmt]

As I said earlier, I'm the last remaining High Priest of Tetrahedral Ambisonic mikes

Not really. A (chinese) customer wanted a livestreaming Mic that was different. I tried to get him sold on a first order Amisonic Mic, on the principle that Ambisonic is de-factor VR audio and this could be used for example in nature for an immersive Audio experience.

Extensive DSP build in to reliably make livescreamers sound ok, so compressor, autotune, reverb, sampled sound FX. Nice Brass 25mm Electret capsules. Wired USB or Wireless (aptX . I had intended a secondary software option for "recording" use. And a second version with polarisation and real condensor capsules.

Customer declined and instead got his brand screened on a BM800 and "livestreaming sound card". Last I looked the bundle was still for sale on Taobao for less than factory cost.

I got to try a Calrec Soundfield in the front of my "Triangular Microphone setup with dimensions similar to a Decca Tree and similar general intention, that is however nothing like a Decca Tree to appease certain people". I liked it, but I would probably have needed a lot more time to get the measure of it and get the best out of it. Alas, even 5th or 6th hand the price was insane for me.

If anyone wants to DIY one (worth a try), the new Chinese Brass 25mm Capsules are probably a good call for a first try. More details here:

Soundfield microphone by K Farrar · WW October 1979

My Fantasy Audio Christmas Present - SoundField Ambisonics Microphone

Make a 3D printed tetrahedron to hold the capsules.



Electronics are unchallenging.

It's probably one of the most interesting microphones to DIY and the answer to "what is the best single microphone to record classical music with".

Thor

 

[thor.zmt]

There are only 2 arrangements that accurately capture the sound of a good hall.

• Blumlein coincident Fig 8s @ 90 which also gives very good localisation of sources on speaker playback
• Omnis. Spaced omnis give good sound and usually have better LF than modern Fig 8s or cardioids except TetraMic. But localisation is non-existent.

Place a baffle behind the Blumlein array (to limit rear pickup) and place your spaced Omni's in a configuration that would be called by many a Decca Tree.

Except it is not actually by Decca, does not use the distinct flown "tree" structure, uses different microphones to the original Decca Tree and mustn't be called anything remotely like "Decca tree", lest the universe collapses and is replaced by something even more incomprehensible and challenging than what we have now. Some say that somebody already said that though.

Other coincident or semi-coincident configurations can be used in front.

The sound processing should be obvious. Front pair main stereo Array, Lowpass on the Omni's as "bass fill in" for the front array's rather castrated bass, extra level controls on a gently sloped down (x-curve) filtered Omni full bandwidth. Back in the 80's I had a pre/mixer combo box I made (as part of my Tonmeister "Meisterstueck") for this with Mic's being generally Microtech Gefell.

Seems this is kinda used quite frequently these days. I "invented" (I am sure a dozen guys will jump up and claim they did it before me - probably - not claiming priority, just independent work) this setup in the 80's in what was then communist East Germany. I can recommend it.

Thor