MXL-990 Transformer Conversion Mod


Choices for Stock or Improved Headbasket

Instructions for shipping your mic to us will be provided after checkout

  • Options Price: $0.00
  • Product Price: $279.00
  • Total: $0.00
SKU: 990-u-bfm Category:


This is a Mod /  Rebuild of your microphone.

Our BFM Transformer-Coupled Circuit is now available for the MXL 990!  This Transformerless MXL Mic is transformed into a whole new beast! We use a high quality boutique quality CineMag transformer standard. The BFM Circuit board is all discrete and individually hand-biased.  Capsule choices are a high quality K-47 style Center Terminated or a CK-12 style Edge Terminated LDC.  The capsule is carefully wired to the circuitry with point-to-point wiring. These are not kits from Mic-Parts or anyone else. The boards are our own branded RockScience designs and the Capsules are imported directly.

The stock MXL headbasket can be left alone (not recommended), Improved or Replaced.  We can improve it by removing some of the inner mesh layers. We can swap it out with a high quality replacement from (subject to availability).

Standard Upgrade:

  • Replace MXL SDC capsule with a K47-style or CK12-style LDC
  • Replace MXL low quality electronics with our fully discrete BFM-990 circuit and CineMag transformer.


  • Internal Cardioid/Omni Pattern Switch.
  • Improve the existing Headbasket by removing screen layers.
  • Replace existing Headbasket with one from Mic-Parts

Contact me first if you have any questions about the upgrade or the options.

There is a modest drop in output level when putting the mic in omni mode with the internal pattern switch. The body must be unscrewed to access this switch


Additional information

Weight 4 lbs
Dimensions 10 × 12 × 8 in


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