I bought my first large-diaphragm condenser mic in 2004 for about $100: an Apex 420 that (along with many inexpensive mics of that era) was built on the same circuit as the MXL 2001. These accessible FET and real transformer-based condensers included a smaller-sized (32 mm) version of the K67 (34 mm) capsule, which together with their inexpensive internal components resulted in a brassy sound prone to distortion. I also own a pair of older MXL 991 pencil condensers that a client traded me against their bill. The capacitor only 2001 & 990 mod kits from MicModKits.com are curated to upgrade a variety of low-cost mics that implement a similar topology – check the website for make/model compatibility. More exhaustive mod kits (e.g. MicParts) include replacement of the entire circuit board, with capsule and headbasket upgrade options to offer a premium sonic improvement, but the investment can easily be twice the cost or more of the mic you’re upgrading, which is daunting for those (like me) that haven’t worked much with circuit boards. I figure at $12.99 and $9.99, these 2001 and 990 mod kits are worth the risk.
I began with a single 990 mod kit for one of my MXL 991s. The kit’s name was a “head-scratcher” at first, but it turns out that the circuit designs for the larger diaphragm MXL 990 and the small diaphragm 991 are similar. The kit’s single polystyrene Styroflex capacitor and two metal film capacitors are meant to replace the more cost-effective (mostly ceramic) ones installed by the manufacturer. PDF instructions are thorough, but not verbose. Basic tips, recommendations, and troubleshooting resources are a bonus, but for circuit board soldering newbies I’d encourage some YouTube research at minimum. The 990 kit mod was simpler than expected, but removing old capacitors became a circus trick of prying from the top while simultaneously heating with the soldering iron from the other side. This would’ve been much easier with a bench clamp, but I powered through freehand, only burning myself occasionally. After removing the original caps, I desoldered the board with a wick to open the through-holes so I could more easily solder in replacements. Top-mounted components were easy to attach, but the single bottom side Styroflex caps on all kits required a little more finessing. I ran into some trouble with the seven-capacitor 2001 kit. My Apex 420 (and other MXL 2001-based designs I assume) has two circuit boards that need to be pulled away from the microphone’s body skeleton for modification. During this process, two wires snapped free from solder joints that I couldn’t see. My first impulse was to turn off the iron and drop the mic in the trash can. But because MicModKits.com recommended I photograph everything, I had the pic showing the attached wires so I could restore the broken connections – whew!
All three mods were a relative success, resulting in super-noticeable sonic improvements: more detail, increased frequency response, lower noise floor, and less audible distortion. The 990 kit was totally worth the trouble, but the 2001 kit knocked it way out of the park – and even further after performing the included Bonus Headbasket Mod. I feel like I’ve more than doubled the quality of all these mics, and it was a fun/confidence building-learning experience. If you’re waiting for an invitation to elevate your entry-level mic, I just gave it to you. Jon Goad puts these kits together in his rural Arkansas home studio, where he supports his gear-buying habit by selling mod kits, custom cables, plus the two (PC only) software titles that he’s developed for project studio owners and gigging musicians. Free shipping. Stay tuned for my capsule upgrade!