RK-87C Microphone Capsule
The MicParts RK-87C is a large-diaphragm, 34mm OD, true condenser capsule. It is based, both physically and sonically, on the Neumann K67.
The backplates are solid brass, made with precision CNC machining. The diaphragms are genuine DuPont brand Mylar film. The front diaphragm is metallized with gold.
The capsule has two diaphragms, as do all K67s. The rear diaphragm is clear Mylar. This capsule works in Cardioid. It will not support alternative polar patterns; If you are building or modifying a multi-pattern microphone, see the RK-87.
Beware Cheap Capsules
The capsule is the most critical component in any condenser mic. It determines the mic's frequency response, tone, and sensitivity.
Too many DIY microphone builders are surprisingly unaware of this, as evidenced by the popularity of cheap capsules -- many of which claim to be MicParts' own RK series designs. These cheap capsules could turn your handcrafted DIY mic into a doorstop. Low output? Thin bass? Noise? If your capsule sounds bad, the mic will sound bad -- no matter what magical tubes, transformers, and capacitors that anonymous guy on Gearslutz raved about. ;-)
Great condenser mics could have any number of different topologies, features, and sounds, but they all have at least one thing in common: a fantastic capsule... because that single component is responsible for most of the sound of the microphone.
We're happy to help you determine whether this particular capsule is right for your mic, but whether it is or not, we strongly encourage all mic builders to avoid the factory reject capsules, the counterfeits, and the knock-offs being sold by companies with no ears, no experience, and no test gear.
MicParts' Capsule QC Process
Every MicParts RK-87C capsule is tested on an acoustic sweep rig. This gives us a comprehensive picture of the capsule's frequency response performance, which is one of the two most critical performance characteristics of any microphone capsule.
Capsules are also tested for diaphragm tension, sensitivity, and noise.
The Neumann K67 Sound
The graph below shows a typical RK-87C (formerly called "K67-S") response, compared to a genuine Neumann K67 (~$600) in the same fixture.
The bass response of the MicParts RK-87C is slightly fuller than that of the Neumann capsule (+1.8dB @ 60Hz). We consider that to be a benefit. It's easy to roll off low-frequency content within the circuit design, or via a preamp's HPF switch, or via digital EQ in the DAW -- but you can't as easily add in low frequency information via EQ if it isn't captured by the mic in the first place. Said another way, having strong bass response in the capsule is a good thing.
The MicParts RK-87C has an identical response to the Neumann K67 from 400Hz to 7000Hz. Above 7k, the RK-87C has fractionally more output (<1dB) through ~12kHz, then 1-2dB more "air" above 12kHz.
Over the entire range of critical vocal frequencies, this capsule has identical output to the Neumann K67.
We include a short mounting post, backplate termination wire, and all the screws necessary to install the mount and capsule into your microphone.
We pack every capsule with a desiccant to prevent moisture from adversely affecting the capsule during shipping.