Microphone Mods

Microphone Mods, Upgrades & Rebuilds

Whether you’re looking for your first studio condenser microphone, or already have a mic locker full of boutique treasures, our mic mods and builds are great additions to any studio. For Mods/Rebuilds, we can work on your mic, or you can choose from our stock of finished mics. We also do Custom microphone Builds, which are built from scratch and available in Transformerless or Transformer-Coupled versions. All of our microphone work is done by hand with great care using fully discrete circuitry and various microphone capsules. Interested? Read on! Questions? Contact us.

These are not “diy microphone kits”. We do all the builds, testing and verification in-house with our own components and designs. What we ship to you is always a finished, working and awesome microphone.

Upgrade Your Locker!

We fully rebuild/mod models from MXL, CAD, Sterling Audio and others.

We stock various rebuilt models by MXL, Sterling Audio and others. We also have our RS custom built mics here.


Flavor Guide

There are no hard rules to this, but below is a general guide to choosing a flavor based on the intended use. The table headings are indicating Transformerless (TL) and Transformer-Coupled (TC) for both K47 and CK12 style capsules. Generally, the K47 builds are more versatile but the CK12 capsules can really shine in some specific applications. The TL builds are probably more pristine but the TC builds have more harmonic color. Most microphones can be rebuilt in any of the configurations below (with a few exceptions) and our own RS series mics can be built in any flavor. Please contact us for more specific details.

SourceK47 TLK47 TCCK12 TLCK12 TC
Male Vocal♥♥♥♥♥♥♥♥♥♥♥♥♥♥♥♥
Female Vocal♥♥♥♥♥♥♥♥♥♥♥♥♥♥♥♥♥
Elec Guit Cab♥♥♥♥♥♥♥♥♥
Elec Bass Cab♥♥♥♥♥♥♥♥♥
Acoustic String Instr♥♥♥♥♥♥♥♥♥♥♥♥♥♥♥♥♥♥♥
Drums / Lo Freq Percussion♥♥♥♥♥♥♥♥♥♥♥♥♥♥
Hi Freq Percussion♥♥♥♥♥♥♥♥♥♥♥♥♥♥♥♥♥♥

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 100 bucks. While they do a pretty good job with the mechanical design, they must cut every corner on the electronics and capsule to make that price. 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). Our boards are hand-assembled with very high quality discrete thru-hole components including low noise resistors and film capacitors in the audio path. We hand-match the output transistors on each board. We also hand pick and bias the FET on each board. This attention to detail is lost in mass-production mics.

mxl990 circuit
MXL990 Board (L) and our jaSb 990 (R)

What do they sound like?

Every sound you hear in this video was recorded with our transformerless mics. There is no EQ on anything, nor on the final mix.

Featured Mics:
* Our RS/47 (three)
* Rebuilt MXL 550
* Rebuilt MXL 990

All of the mics are using our k47 style capsule and jaSb transformerless circuit.
Recorded at RockScience and at NewClear Studios

YouTube player

Capsule Flavors

ldc capsules
K47 (L) CK12 (R)

Our standard configuration is to use a K47-style Center-Terminated LDC Capsule. The k47 design yields a wide, flat frequency response with full low-end, harmonically rich mids and a smooth, non-harsh top end. The K47 paired with our Transformerless jaSb circuit, is extremely versatile. That is the configuration used in every mic on the Mictastrophe video.

Optionally, we can use a CK12-style Edge-Terminated capsule. The CK12s have a little less of that mid-forward energy of the K47 but more of an extended silky top end. They are generally brighter sounding and they pair nicely with our Transformer Coupled circuits. They will put a nice top end sheen on background vocals, or stringed acoustic instruments or percussion.

Circuit Flavors

All of our circuits use a directly coupled FET at the capsule input. But we offer two distinct flavors of circuitry: Tranformerless and Transformer-Coupled. What’s the difference?

Transformerless (TL)

Our all-discrete jaSb (just another Schoeps board) board is a “Schoeps Style” circuit built with high quality, low noise components on a quality USA Fabricated circuit board. This circuit is based on the Schoeps CM-5 which is a elegant microphone amplifier circuit and is the basis for most transformer coupled mics built today. The slightly self-deprecating “just another” in the acronym is because this is a very common approach for transistor coupled mics. Our 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).

Transformer-Coupled (TC)

Our BFM Transformer coupled circuit is based on the Neumann KM84 mic circuit adapted to a Large Diaphragm Capsule. This elegant design yields an incredibly pristine tone with some 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! Neumann’s KM prefix stood for Klein Mikrophone – small microphone – like the KM84 and KM184, etc. Being adapted to a large capsule, we gave our circuit the BFM (Big F’n Microphone) prefix.

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. The standard “800” version of the BFM will fit in most transformer coupled mics from MXL and others. Both boards have the optional internal pattern switch. We also have an adapter board which can transformerize most transformerless mics!

Transformer Choices

  • A CineMag 5722w 6.9:1. This is a very high quality transformer yet still moderately priced. It is CineMag’s recreation of the BV107 that was in the KM84 which our circuit is based on. It has better harmonic distortion characteristics and a bit more of that transformer sound than the Chinese one. Overall, this is probably the one to go with for most applications.
  • A Tab-Funkenwerk 6.5:1 T12 style. This is the highest price option and is very high quality. It has very full lows and low-mids with lots of great harmonic distortion. It is the definition of fat! It’s an excellent choice for low frequency applications like Kick Drum or Bass Cabs. It’s not dull by any means, but because it is so fat and full in the lows, it can make the overall tone of the mic a bit dark and heavy. The AMI is also a great choice for CK12 capsule build because the brighter capsule compliments this full bottom end beautifully