In the case of the 990, a new large-diaphragm capsule will lower the mic's self-noise too. Click for more information on replacement grilles for the MXL 990. The mod service offers our renowned transformerless circuit, which is also available as a DIY kit, plus a new transformer-coupled topology that is exclusively available in our handbuilt microphones. The mic's capsule gives you 90% of the sound of the microphone. If you're looking to add some saturation and vintage tone to your mic collection, this is a great way to go. We also offer a boutique upgrade service for the 990. Roll off the highs to correct for an over-bright/peaky capsule, or as a darker mic for taming bright/thin sources. These capsules can be installed onto the MXL 991 without tools. These premium small-diaphragm condenser capsules are available in both Cardioid and Omni varieties. 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. Pre-pad the mic by 6dB without adding capacitors. The other problem is that the circuit is built with inexpensive and indifferently-selected … We make our own custom 2-layer PCBs in the US, and provide a complete circuit's worth of handpicked and matched components. Whereas most MXL SDC capsules have attenuated bass, a 5dB drop around 4–6kHz, and a boost around 15kHz, we created a capsule that is full and rich sounding across the sonic spectrum. This kit fits all generations of MXL 990. My mod was based off of this link: Gus' MXL 603 mod. The MXL 991 is an inexpensive pencil condenser with a few significant barriers to great performance. Our custom, handmade headbaskets for the MXL 990 provide a significant cosmetic upgrade. This kit fits all generations of MXL 990. We have three DIY modification options for the MXL 990. Another benefit of this circuit replacement is that it enables you to use the RK-12 or RK-87 capsules. Our Cardioid capsule is voiced with a relatively flat frequency response. The RK-87 should only be used with high-frequency attenuation in the circuit. Are you looking for a simple upgrade, or a full rebuild? Both are more brightly voiced than the RK-47. The capacitors I have replaced are the same value as described in the mod forum post. The other problem is that the circuit is built with inexpensive and indifferently-selected parts, resulting in mediocre performance. The result is linear from 20Hz–20kHz, with very low self-noise and distortion. Both are more brightly voiced than the RK-47. In the MXL 990 and 991 it’s located on small standoffs on the underside of the printed circuit board. The 990B circuit kit provides this; parts and instructions are included. To clarify: I have not replaced the C13 ceramic with a polystyrene yet. For the MXL 990, we recommend the RK-47. Click for more information on our MXL 990 PCB kits. They work nicely with the stock circuit (and they work even better with our custom Schoeps replacement circuit; see below). Original ceramic.001uF (marked 102) on the left,.001uF/100V styrene film replacement on the right. Wednesday, December 5, 2012 MXL’s 991 small pencil condenser microphone is sold as a set with the 990 at Guitar Center and Musician’s Friend. Here’s the 990: One easy improvement to inexpensive MXL mics is to replace the ceramic capacitors in the signal path. These are available in two colors, "satin nickel" and "black chrome." We even have a video about it, and a sound sample below: If you've never upgraded a mic before, you might wish to start with something very simple. It is the only circuit mod on the market for newer 990's made with surface-mount circuit boards. In the case of most inexpensive condensers, the capsule is a $5-$10 part that, frankly, does not sound very good. It has a 22mm OD capsule, about 3/4”, with a wide cardioid pattern. Click for more information on replacement grilles for the MXL 990. It is the only circuit mod on the market for newer 990's made with surface-mount circuit boards. Two build-time options are provided to allow personalization of the mic: Read more about the Transformerless SDC Circuit Kit. Click for more information on our MXL 990 PCB kits. Modifying the MXL 991 Capsule. We have what you need. If you plan to use the microphone primarily on high SPL sources, use the included parts to cut the mic's sensitivity by 6dB via a noncapacitive pad option. I finally fit the giant Radioshack metal film capacitors into my MXL 991. 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. And it can be replaced by soldering just two wires. Fortunately for MXL 991 owners, we have replacement solutions for both the circuit and the capsule in this mic, which give the 991 performane on a par with European SDCs costing 5-10 times more.