Initially ambisonic microphones – made by Calrec, called Soundfield microphones – were expensive because they were analog, which meant each microphone had to be trimmed to create a B format signal.
In the last ten years, the technology has changed. The calibration is done in software, and the microphones themselves have become simple and light.
Apart from that, the pricing of each make of Ambisonic microphone is determined by the manufacturer. I built my first ambisonic microphones because I could not afford to buy the ones in the market. I want to keep the price as low as I can, so many people can buy these microphones and do these recordings.
There are currently three microphones with this level of quality and technology. In terms of price, Brahma comes out at the bottom , with Core Sound Tetramic in the middle and Sennheiser Ambeo on top. Brahma always comes with a calibration file – you don’t have to ask for it.
One way this has been possible is because we do not have a factory to make the parts. In Bangalore, it is possible to find small scale machine tool operators who will make the parts we need. The part that need the greatest precision – the tetrahedral frame for the four capsules, is printed in a new high strength nylon, in a factory in the Netherlands.
Calibration of the microphones has also become easier, thanks to techniques that rely on quasi-anechoic methods. You need a high quality calibration standard, but do not require an anechoic chamber any more.
Precise calibration is the real secret of Brahma microphone quality. The process creates four virtual microphones of B format. It also aligns the frequency response of these four virtual microphones with the high quality measurement microphone used as reference.