_Pushbutton Filter Circuit Upgrade Kit

$ 139.00

We have discontinued this circuit mod kit. The MP-V57 PCB kit should fit all the same microphones, while providing an easier build and superior sound quality. The MP-V57 is a newer revision of the same circuit used by the "Pushbutton filter" circuit.


This circuit upgrade kit is compatible with a number of inexpensive condenser microphones, including:

Click the thumbnail image at left to confirm compatibility with your microphone. Your microphone is compatible if and only if its circuit looks like the one in the photo.

This circuit mod kit includes hand-picked replacement components for the entire audio circuit of the microphone, plus US-made silver teflon wire to upgrade the mic's internal wiring. Choose any of our large-diaphragm capsules to tune the modded mic to your specific preferences.

Product Features

  • Audio circuit mod designed by Jim Williams
  • Includes matched audiophile-grade capacitors and resistors
  • Includes super-low-noise transistors
  • Includes full-color, 30-page installation manual

The circuit in these microphones is a version of the classic Schoeps transformerless circuit, which when upgraded with our modification kit performs on par with mics costing 3-5 times more.

The mic's circuit board contains a switchable high-pass filter, which enables you to remove rumble, mechanical vibrations, and to reduce proximity effect when close-miking a source.

What's Included

Each mod kit includes hand-selected components to replace 100% of the mic’s audio circuit and selected parts of the DC power circuit. We also provide a length of US-made silver-plated Teflon insulated hookup wire, to replace the substandard wire connecting the mic’s two circuit boards.

What's NOT Included

We strongly recommend replacing the mic's capsule, as that is responsible for most of the tone of the mic. The circuit upgrade will lower self-noise, raise sensitivity, reduce distortion, and "unclutter" the sound, but the frequency response and tone depend on the capsule.

Because this circuit mod kit can provide high-frequency attenuation (such as is found in the U87 circuit), you can choose to use a brightly-voiced capsule such as the RK-87. The RK-47 and RK-12 are both excellent choices too.

Installation Procedure

This kit requires desoldering many components from the stock circuit boards. For this reason, this kit is arguably more difficult than some of our other kits. Desoldering is actually harder than soldering, because there is increased risk of overheating the circuit board.

If you are new to soldering (or, more to the point, new to desoldering), we recommend practicing on a scrap PCB. Or, purchase an electronic desoldering tool such as the Hakko FR-300 listed here.

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