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Circuit Mod Kits

Tape Op #100The results surprised and amazed me. On playback of the first takes, I was stopped in my tracks, staring at the speakers. On listening to the lead vocal, my first unedited thoughts were, "I must have this," and "this sounds expensive."

Read the Tape Op Magazine review of the 990B PCB kit.

[T]hey made the kit sound great. Cymbals are smooth and finally under control. The cymbals are so smooth, without peaking frequencies, and especially noticeable is the absence of harshness around 3k-4k. The cymbals shimmer, which is what I've been hunting for with EQ, reverb and compression, to no avail... Now the drum kit is much easier to mix.

Read George Capone's review of the Apex 460 Mod Kit.

...After getting everything finished, the mic has a very pleasant tone - extended bass, nicely thickened upper-bass and low mids, and a balanced high end.

I'll definitely be doing this again.

Read Don Kennedy's full review of the MXL 990 Basic Mod Kit.

...The RK-47 sounds great--very open, no annoying highs. The RK-7, as described, has a very warm and darker vibe that I like better on my voice, but might not like better on instruments...

So my conclusion is that Microphone Parts offers a really good product. If you have an MXL 990 around this will make it a much much much better mic.

Read Michael O'Malley's review of the MXL 990 Basic Mod Kit (contains photos).

Seriously, this mic is unbelievable... For a total outlay of about $260, including a new 990 mic ($50 from GC), this mic can't be beat for the price.

Read Paul McCloud's report on the MXL 990 Advanced Mod Kit.

So yes, top notch components do make a difference. MXL's economy parts measure pretty well, but you can pull more out of the circuit. The Microphone Parts kit makes an effective upgrade pretty much a no-brainer. The hard work and cut-and-try development has been done for you. The manual guides you step by step. If you know how to solder, you can do it yourself.

Read Henry Spragens' report on the MXL 990 Advanced Mod Kit.

I am very happy with the sound of the modded mic. I can hear a much more poised and balanced sound, most notably, the extended freq range on the bottom end and the smoother high-end. The mod has also greatly reduced the mic’s self-noise. Overall it feels warmer with much improved capturing of the fine detail.

Read Dave Boulden's report on the Apex 460 tube mic mod kit. (contains photos)

There's actually something mystifying about this modified microphone, it sounds so natural, so clear!! A foot away sounds as if you are right up there, while right up there sounds in your face, but still very smooth. We're confident that vocal tracks recorded with this microphone will need a lot less processing. Plus, we could listen to anyone for hours through this mike, because it is a lot less tiring too. We've just started believing in the benefits of modifying your microphones!

From a great review of the GXL2200 / Apex 435 / SCM-800 mod kit, originally published on Eli Audio.


The microphone capsule (RK-47) you supplied as an upgrade to the NT1A’s standard capsule made sibilance a non existent thing of the past. I used to think when I first recorded my voice, "Why are my s's so hissy...?" I am now an extremely happy chappy because the sound is 100 times better... Thanks to Matt at for giving the best customer support I have ever seen!

Read Glenn McKenzie's full review of the RK-47 capsule (in a Rode NT1-A).

Does this sound like a, now, $175 microphone? No, it sounds more like a $1000 microphone to my ears. All it took was a $100 part, some intermediate level soldering tasks, and it went from sounding OK to Amazing.

Read Jordan Reynold's full review of the RK7 capsule (in an MXL V67G).

A nice neutral pair of mics. Very natural sound character, with a very slight emphasis in the upper mids centered around 4KHz, and a gradually falling top end above 11 KHz. No zip or extra air, but not dark sounding, either. Quiet with excellent S/N and extended LF response. These should be useful for all sorts of instruments and ensembles. They are high performance mics of the same calibre as the high price German brands. Pro quality studio mics can be built on a budget from readily available parts.

Read Henry Spragens' full review of the RK-47 capsule (in a DIY condenser mic).