MXL 990 Mods

MXL 990 Microphone

We have many DIY modification options for the MXL 990. Are you looking for a simple upgrade, or a full rebuild? We have what you need.

Boutique Mod Service

We offer a boutique upgrade service for the 990. You'd send us your microphone; we'll upgrade its capsule, circuit, paint, and grille. We'd work with you to select which of 5 capsule/circuit combinations best meets your needs, and then we'd custom-build the microphone just for you.

The mod service allows you to pick either a transformerless or transformer-coupled circuit, and any of about six different capsule / voicing options.

DIY Mod Options

We even have a video about it, and a sound sample below:

#1: Capsule Replacement

RK-47 capsule

If you've never upgraded a mic before, you might wish to start with something very simple. The mic's capsule gives you 90% of the sound of the microphone. In the case of most inexpensive condensers, the capsule is a $5-$10 part that, frankly, does not sound very good. Our line of premium replacement capsules will re-voice your mic, giving you a much smoother and more musically useful sound. In the case of the 990, a new large-diaphragm capsule will lower the mic's self-noise too. And it can be replaced by soldering just two wires. For the MXL 990, we recommend the RK-47. This capsule makes a wonderful all-purpose microphones, with great detail in the mids, and a neutral to dark top end -- a welcome contrast to most over-bright condensers.

#2: 990 Circuit Replacement Kit

990B PCB kit

Our premier mod kit for the MXL 990 replaces the entire circuit board with a high-quality, made-in-the-USA, dual-layer board with our full suite of audio enhancements and a Cardioid/Omni switch -- making your MXL 990 into a multipattern microphone with exceptionally low noise and high resolution. This kit fits all generations of MXL 990. It is the only circuit mod on the market for newer 990's made with surface-mount circuit boards. Click for more information on our MXL 990 PCB kits.

Another benefit of this circuit replacement is that it enables you to use the RK-12 or RK-87 capsules. Both are more brightly voiced than the RK-47. The RK-12 could be used with the stock 990 circuit, but might be a bit too bright on some sources. This is a matter of personal preference; some users tell us the RK-12 on a flat-response circuit is the best acoustic guitar mic they've ever heard.

The RK-87 should only be used with high-frequency attenuation in the circuit. The 990B circuit kit provides this; parts and instructions are included.

#3: 990XF Circuit Replacement Kit

990XF Circuit kit

New for 2021, the 990XF circuit kit provides a more vintage and saturated tonal option than the transformerless circuit above. This transformer-coupled design, like our T-84, creates some harmonic content to complement the source.

This circuit is our easiest-to-build large-diaphragm option, with only 20 components on the PCB. (The low parts count is not an indication of sonic compromise, but rather of circuit elegance -- after all, it was good enough for Neumann.)

#4: Custom Headbasket

MXL 990 custom headbasket

Our custom, handmade headbaskets for the MXL 990 provide a significant cosmetic upgrade. These are available in two colors, "satin nickel" and "black chrome." Click for more information on replacement grilles for the MXL 990.


Audio comparison to $3200 Neumann U87 Ai