5 Homebrew Electret & Condenser Microphones
Channel: Michael Brooks
Date: 2022-03-19

I got a bit obsessed with modding and building microphones. Here are five Frankenstein mic builds I've put together from various microphone donor bodies and capsules.

A particular thanks to Jules Ryckebusch (@SoundSleuth) for his excellent Instructables guides which inspired these builds.

Mic #1: Schoeps 4 mini electret
- Body: Maplin "Prosound" dynamic mic
- Capsules: RS PRO Omni-directional 6mm through-hole electrets (https://uk.rs-online.com/web/p/condenser-microphone-components/7717014/)
- Circuit: Schoeps on matrix board

Mic #2: Pimped Alice dual large electret
- Body: BM900 (longer version of BM800 cheap Chinese mic https://www.aliexpress.com/item/32965747653.html) 
- Capsules: Generic 25mm large capsule electrets (https://www.aliexpress.com/item/1005002754179284.html), or if you want better quality and are in USA or don't mind high shipping fees TSB2555B (https://www.jlielectronics.com/microphone-capsules/jli-2555bxz3-gp/)
- Circuit: Pimped Alice on matrix board (see guide https://www.instructables.com/Modify-a-cheap-LDC-Condenser-microphone/)

Mic #3: 8-capsule electret BM900 mod
- Body: BM900 (longer version of BM800 cheap Chinese mic https://www.aliexpress.com/item/32965747653.html) 
- Capsules:
---- 4 x Generic 25mm large capsule electrets (https://www.aliexpress.com/item/1005002754179284.html) x 4 
---- 4 x Generic 16mm electrets (https://www.aliexpress.com/item/1005003730512330.html)
- Circuit: Native BM900 with lower noise 5.1V Zener + low pass RC filter on DC rail
- Grille: Isopon Aluminium Mesh (https://www.amazon.co.uk/UPOL-UPPM1-Isopon-Aluminium-Mesh/dp/B002HMXSYE/)
[You're nuts if you want to build this mic.]

Mic #4: LDC Alice full condenser
- Body: BM900 (longer version of BM800 cheap Chinese mic https://www.aliexpress.com/item/32965747653.html) 
- Capsule: 34mm large diaphragm true condenser (https://www.aliexpress.com/item/1005001812729736.html)
- Circuit: LDC Alice on matrix board with inductor-based DC bias generator

Mic #5: 
- Body: BM800 (https://www.aliexpress.com/item/32965747653.html) 
- Capsule: 77JC 34mm large diaphragm true condenser (https://www.aliexpress.com/item/1005003678267502.html)
- Circuit: OPA Alice + hex inverter DC-DC (see: https://www.instructables.com/True-Condenser-OPA-Mics/)
---- PCB #1: Dual OPA Alice in blue (https://www.pcbway.com/project/shareproject/Hex_Inverter_Voltage_Multiplier_for_Condenser_Microphones.html)
---- PCB #2: DC-DC Hex Inverter Multiplier in red (https://www.pcbway.com/project/shareproject/Hex_Inverter_Voltage_Multiplier_for_Condenser_Microphones.html)
----- Operational amplifier: OPA1642 (https://www.aliexpress.com/item/4000409695165.html)

I have since built a microphone using a clone U87 body (https://www.aliexpress.com/item/1005003485396201.html), the Mic #4 34mm true condenser (not the 77JC one), and the two PCBs from Mic #5. The results are outstanding. Very low self noise and excellent sensitivity.