We've just launched an all-new and massively updated website, with a directory of mic mods that covers 39 popular inexpensive condensers.
Here are some product highlights:
"Fox 460" mod kit for Apex 460 / T11-A / CTM-100
This is a 3rd-generation Apex 460 mod. It's our best yet -- the most fun to build, and the best specs to date.
Features:
Benefits:
This has been our fastest-selling product. The lacquer is drying on our 3rd production run of transformers, so we'll be able to ship new orders soon.
Here's a before-and-after distortion graph to compare the stock circuit (6% distortion!) to the modified circuit:
FHX Ribbon Upgrade for Cascade Fathead
Designed by Marik (Mark Fouxman) of Samar Audio, the FHX kit includes a precision ribbon motor and toroidal transformer.
It has a longer ribbon and longer magnets than most of these medium-short ribbon designs, and a shorter front-to-back audio path, and a very small and consistent gap between magnet and ribbon. This gives the motor a wider and more balanced frequency response, and a clearer sound -- while still sounding unmistakeably like a ribbon. Customers say they're able to use the FHX on sources where the Fathead was just too muddy, too midrangey, too thick.
The toroidal transformer gives the mic a wonderful sense of 3D spaciousness, especially in stereo pairs.
"U87 EQ" Circuit mod for Studio Projects C1/C3
If you find your C1/C3 to be too bright, we have a really great fix: an add-on PCB that recreates the corrective EQ curve found in the U87. It is an inexpensive and easy way to take the peaky, sibilant, hyped edge out of the C1/C3.
This kit is in its 2nd generation, with upgraded, US-made polypropylene signal capacitors.
Here's a before-and-after frequency graph of the circuit (note: not an acoustic test, but a signal injection test to demonstrate the circuit's rolloffs):
The high-frequency rolloff is adjustable via a trimmer on the new EQ board.
S-47, S-87, S-12 Microphone Kits
These kits contain parts comparable to several $1000+ microphones we've seen (at least two of which we're actually supplying parts for, ssshhhh!).
The circuit is our highly optimized take on the Schoeps transformerless design. We supply fantastic parts -- 1% resistors, matched signal caps, a NOS JFET (pre-biased manually for each kit in our shop), and a 3rd-gen PCB design that is built for DIY.
The kit includes:
The resulting mic has fantastic specs:
Large-diaphragm Capsules
Here are some product highlights:
"Fox 460" mod kit for Apex 460 / T11-A / CTM-100
This is a 3rd-generation Apex 460 mod. It's our best yet -- the most fun to build, and the best specs to date.
Features:
- Based on a circuit design by Brian Fox
- Custom, US-made PCBs
- US-made polypropylene output cap
- Custom-wound US-made transformer
- Color-coded, precut & tinned silver/Teflon wiring
- Choose from U47, U67, C12/ElaM 251 voicing
Benefits:
- Higher output than stock mic
- Lower noise than stock mic
- Much lower distortion than stock mic
- Dial in the high-frequency rolloff that best suits your capsule
This has been our fastest-selling product. The lacquer is drying on our 3rd production run of transformers, so we'll be able to ship new orders soon.
Here's a before-and-after distortion graph to compare the stock circuit (6% distortion!) to the modified circuit:

FHX Ribbon Upgrade for Cascade Fathead
Designed by Marik (Mark Fouxman) of Samar Audio, the FHX kit includes a precision ribbon motor and toroidal transformer.
It has a longer ribbon and longer magnets than most of these medium-short ribbon designs, and a shorter front-to-back audio path, and a very small and consistent gap between magnet and ribbon. This gives the motor a wider and more balanced frequency response, and a clearer sound -- while still sounding unmistakeably like a ribbon. Customers say they're able to use the FHX on sources where the Fathead was just too muddy, too midrangey, too thick.
The toroidal transformer gives the mic a wonderful sense of 3D spaciousness, especially in stereo pairs.

"U87 EQ" Circuit mod for Studio Projects C1/C3
If you find your C1/C3 to be too bright, we have a really great fix: an add-on PCB that recreates the corrective EQ curve found in the U87. It is an inexpensive and easy way to take the peaky, sibilant, hyped edge out of the C1/C3.
This kit is in its 2nd generation, with upgraded, US-made polypropylene signal capacitors.
Here's a before-and-after frequency graph of the circuit (note: not an acoustic test, but a signal injection test to demonstrate the circuit's rolloffs):

The high-frequency rolloff is adjustable via a trimmer on the new EQ board.
S-47, S-87, S-12 Microphone Kits
These kits contain parts comparable to several $1000+ microphones we've seen (at least two of which we're actually supplying parts for, ssshhhh!).
The circuit is our highly optimized take on the Schoeps transformerless design. We supply fantastic parts -- 1% resistors, matched signal caps, a NOS JFET (pre-biased manually for each kit in our shop), and a 3rd-gen PCB design that is built for DIY.
The kit includes:
- A very nice, unbranded donor body
- Our custom PCBs
- 100% of parts needed to build the circuit
- Internal switch that can be built as either a polar pattern (C/O) or -10dB pad
- Your choice of capsule (K47, K87, CK12 style)
- Swivel mount
- Vinyl pouch
The resulting mic has fantastic specs:
- 35-50mV/Pa sensitivity (depends on capsule; RK-87 is generally higher output than the RK-47)
- Very low self-noise, 6-10dBA
- Extremely low distortion

Large-diaphragm Capsules
- RK-47 - based on the Neumann K47
- RK-87 - based on the Neumann K67/K87
- RK-12 - based on the AKG CK-12
