Is it a good idea to wire an ELECTRET mic in parallel? What are the advantages and disadvantages?

I already made a prototype of a low-noise desktop microphone (with an internal 5 stage transistor preamp). It only had one ECM capsule inside. A few days later I found a couple of pictures of a certain microphone with two ECM capsules wired up in parallel. It made me wonder, will it increase the sensitivity of the mic while reducing noise or will do the exact opposite? Is is a bad idea to hook six of these in parallel? Sorry, I'm not an expert when it comes to microphones. Before I post a guide, I wanted to make sure of what I'm saying. 

The Reason:
If you are familiar with the Blue Snowball USB microphone, you'll be surprised on what's in it. I recently discovered that it has two "Electret Condenser Mic Capsules" soldered in parallel. I thought there was something special about the Snowball since the reviews went crazy (4 1/2 stars on amazon)! I was expecting a huge diaphragm, but no, it only had two tiny ECM mics soldered on a Preamp + USB DAC. Lesson learned! Never underestimate an ECM mic. 

The picture is my prototype, it's working great right now. Luckily, the 5 stage preamp is giving zero noise. I'm planning to add a USB D.A.C. and an ECM array on my final version.

Picture of Is it a good idea to wire an ELECTRET mic in parallel? What are the advantages and disadvantages?
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Electrets are capacitance based mics. Putting them in parallel increases the total capacitance, and the available signal, its also how noise cancellation techniques work.

If it is only the diaphragm with nothing else this would probably be right, but many electret capsules already have a (j-)fet included that amplifies the diaphragm swing by switching an operating voltage in a (hopefully) linear manner.

ASCAS (author)  steveastrouk2 years ago

Thank you!


framistan2 years ago

Looks to me like YOU are the expert on this subject. Hope to see your instructable on this subject of placing 2 mics in parallel with signal and noise comparisons. What about 3 mic's in parallel? interesting.