Whether you’re starting out and looking for your first studio-grade microphone, or a seasoned pro with a mic locker full of boutique treasures, my mic mods and builds can be a great addition to any studio. For Mic Mods/Rebuilds, I can work on your mic, or you can choose from what I have in stock. For Custom microphone Builds, I build transformerless and transformer-coupled mics from scratch. Please Contact Me with any questions or read on for more information.

recent mic mods and custom builds

These are not kits. I do all the builds, testing and verification myself at my bench. What I ship to you is always a finished, working and awesome microphone.

Mic Mods / Rebuilds (your mic or mine)

I do full rebuilds of many models from MXL, Sterling Audio, M-Audio and others. This isn’t swapping out a few capacitors. The entire guts of the mic – the Capsule and Electronics are fully replaced with my components. Send me your mic to rebuild or choose one from my stock of rescue mics. If you have a low cost MXL or other mic that you have outgrown, a rebuild will give it a new life which you will find many uses for.

Custom Mic Builds (RS series mics)

I build mics from scratch into cylindrical BM800 style bodies. My RS series of mics are built with the same components as I use in my rebuilds. Available in both Tranformerless and Transformer-coupled versions, they have a small footprint ideal for getting into tight spaces and sound amazing.

What’s all this Discrete Stuff About?

It’s amazing to think that MXL can build something like a 990 and give it a street price of under a hundred bucks. While they do a pretty good job with the mechanical design, every corner must be cut on the electronics and capsule to make this possible. For high-volume manufacturers like MXL, this means mass produced surface-mount Tech (SMT) circuit boards. Most MXL boards are based on the Schoeps design (as is my jaSb board). My boards are hand-assembled with very high quality discrete components including low noise resistors and film capacitors in the audio path. I hand-match the output transistors on each board. I also hand pick and bias the FET on each board. This attention to detail is lost when you mass-produce.

discrete microphone circuit
Typical MXL board (L) and my jaSb (R)

What do they sound like?

Every sound you hear in this video was recorded with my transformerless mics. There is no EQ on anything, nor on the final mix. Recorded at RockScience and at NewClear Studios

This video illustrates the before/after improvement to an MXL990. This is the typical improvement to any MXL SDC with my transformerless rebuild. Guitars, bass and vocals are recorded with the mic under test and there is no EQ on anything.


All of my builds use a FET at the capsule input. But I have two distinct flavors of circuits: Tranformerless and Transformer-Coupled.

Transformerless Mics

My all-discrete jaSb (just another Schoeps board) board is a transistor coupled “Schoeps Style” circuit built with high quality, low noise components on a quality USA made PCB. This circuit is based on the Schoeps CM-5 which is a elegant microphone amplifier circuit. The slightly self-deprecating “just another” in the acronym is because this is a very common approach for transistor coupled mics. My board uses low noise Vishay/Dale resistors and WIMA capacitors in the audio path. It also has an improved voltage regulator which lets these mics work perfectly on low phantom power voltages (like some Behringer products or video equipment will provide).

mic moc
Standard “800” version of the jaSb
board used in mic mod for MXL990
jaSb board for MXL 990 and MXL 920

Transformer-Coupled Mics

My BFM Transformer coupled Board is based on the Neumann KM84 mic but adapted to a Large Diaphragm Capsule. This elegant design yields an incredibly pristine tone but with that transformer mojo and very low noise. There are more complex transformer-coupled designs, but nothing beats the KM84 for the minimal audio path with only a FET, a single Capacitor and the Transformer between you and the preamp!

A special version of the BFM made for the Sterling Audio ST55 (or Groove Tube GT55) supports the Pad and HP Filter switches on those mics and has the internal pattern switch. The standard “800” version of the BFM will fit in most transformer coupled mics from MXL and others and also offers the internal pattern switch. I also have an adapter board which can transformerize most transformerless mics!

BFM Board used in mic mod for sterling ST55 or Groove Tube GT55
BFM-T-55 board for Sterling ST55
BFM board used for transformer coupled mic mod
BFM-800 for common cylindrical mics
BFM Transformer Adapter Board

The standard transformer I use is a 7:1 imported (China) transformer which sounds very good. But for a premium build, I also offer very a high quality Tab-Funkenwerk transformer from AMI (USA). I did some comparisons between the two here.