Mic Mods

The common term for what I do is mic mods — but that’s not quite accurate. What I actually do are full rebuilds: I completely gut the mic and replace everything inside. Still, if I called them mic rebuilds, the search engine gods would leave me in the dust and you wouldn’t be reading this right now. So, mic mods it is!

I rebuild low-cost large diaphragm condenser (LDC) and small diaphragm condenser (SDC) mics from brands like MXL, Sterling, M-Audio, and others. Custom imported bodies are also in the mix. I work with both transformerless (TL) and transformer-coupled (TC) circuits — with a particular passion for the character and sound of the transformers.

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The Circuits

I build two flavors of microphone circuitry: Transformerless (TL) and Transformer-Coupled (TC). The original TL board is called the jaSb (just another Schoeps board). Like nearly every other low-cost TL mic, it’s inspired by the elegant Schoeps CM5 circuit— adapted here for a large diaphragm capsule. It has very fast transient response and very low noise.

mxl mic mod — Stock MXL surface-mounted board (L) and the jaSb

Next came the Transformer Coupled circuitry. This is modeled after the Neuman KM-84 circuit again adapted for LDCs. I call it the BFM (Big F’n Microphone). These days, I am mostly doing TCs. I generally prefer the harmonic richness and simplicity of the circuit. Like the jaSb, the BFM features discrete high quality components, Point to Point capsule wiring and hand-selected biasing resistors. There have been many adaptations of the BFM for different mic bodies and some of them support external Pad and Filter switches (like for the MXL770/990s, MXL5000, Sterling ST55)

The Capsules

The two capsule types I mostly deal with are k47-style center-terminates and CK12-style edge-terminated. The k47 is a more mid-forward full tone, while the CK12 has a more extended and silky top-end. I will only put k47s in the TL mics but either works wonderfully in the TC builds.

mic mod caspsules — k47(L) and CK12 capsules

I designed custom capsule cradles that fit a variety of mic bodies and support both K47 and CK12-style capsules.

mic mods — Two variations of the capsule cradle

Build Configuration Codes

Every mic has its configuration code engraved on the body. The format is:

47 TC . C
|  |    |
|  |    +-- (TC only) Transformer type: C = Cinemag, A = AMI, 3 = 3U, N = Neutrik(lo-fi)
|  +------- Circuit: TL = Transformerless, TC = Transformer-Coupled
+---------- Capsule: 47 = K47-style, 12 = CK12=style

Examples: