Best electrical design to utilize multiple microphone capsules in parallel?  - Page 1
Forum section: electronics / beginners

author: LooseJunkHater
author_rank: Frequent Contributor
timestamp: September 23, 2025, 05:45:51 pm
content: For years, I've wanted to create my own mic pre-amp, and I've gained quite a bit of knowledge in-part to this forum, and have a broad idea as to how I'll design my future mic pre-amp.Somewhat recently, I've researched + considered utilizing 3x  microphone capsules in parallel for my own DIY microphone.Questions:1. Are therebenefitsto using multiple paralleled microphone capsules? Would it decrease noise + increase signal gain? I'm aware that such a design can introduce various problems. If I recall, frequency + amplitude differences can lead to poor sound quality?2. Would it be best to parallel all mic capsules and amplify the signal via a single mic premaporseparate all mic capsules, utilize individual 1x mic premap each, and then combine all of their signals (I think I'd need to use a "summing amplifier"?).The attached image illustrates what I mean by this second question.

author: RJSV
author_rank: Super Contributor
timestamp: September 23, 2025, 07:14:35 pm
content: My guess would be the latter choice, so that each preamp has a more conventional input, then yes, an op-amp as a mixer of each preamp.Beat interference effects occur when presenting something like 500 hz along with 505 hz, so I believe that basic interference could occur, regardless of your circuit type. ?But the amplitudes should be ok, the outputs simply add together in the mixer.I think it's the program material being run through the system that maybe causes any 'beat or difference' sounds.

author: MariuszD
author_rank: Regular Contributor
timestamp: September 23, 2025, 08:11:01 pm
content: These microphones use a JFET as an amplifier, so they have a current source characteristic. They can be connected in parallel, the signal-to-noise ratio will improve slightly, and the resistor must be chosen so that the voltage does not drop excessively.I suspect a large-diaphragm microphone will still be better.Quote from: LooseJunkHater on September 23, 2025, 05:45:51 pmCombining several microphones will affect the directional characteristics.Quote from: LooseJunkHater on September 23, 2025, 05:45:51 pmI doubt either way is better, I'd choose the simpler one.

author: Benta
author_rank: Super Contributor
timestamp: September 23, 2025, 08:14:05 pm
content: Electrically I see no big difference.But due to the fact that the capsules can't be placed physically in the same spot, I see potential issues for the acoustic sensitivity pattern. This will be angle and frequency dependent to a high degree. Dunno if that's desirable.

author: ahsrabrifat
author_rank: Regular Contributor
timestamp: September 27, 2025, 07:10:58 am
content: It is best to give each capsule its own high-impedance buffer/preamp, then combine (sum) those buffered outputs. Buffers isolate each capsule’s FET and bias network so they don’t fight each other. You can match/trim gains, adjust balance, and avoid DC bias conflicts. Summing after buffering allows elegant isolation and predictable behavior (no current contention or oscillation). Avoid directly wiring multiple electret outputs together to one bias resistor or one input.

author: MariuszD
author_rank: Regular Contributor
timestamp: September 27, 2025, 07:53:33 pm
content: Quote from: ahsrabrifat on September 27, 2025, 07:10:58 amWhy do you think they'll fight each other? These are current sources connected in parallel.Why do you think there will be DC bias conflicts? Microphones have a wide operating voltage range.QuoteWhy? Do you have any scientific arguments indicating that this shouldn't be done?

author: LooseJunkHater
author_rank: Frequent Contributor
timestamp: September 28, 2025, 03:17:57 pm
content: Quote from: MariuszD on September 27, 2025, 07:53:33 pmI can't really tell if you're genuinely asking questions, or are youconfidentthat simply paralleling the mic capsules will provide slightly better performance. I assume you've previously tested/done exactly what I'm planning on doing?