SDC-84 Microphone Kit - Neumann KM84 Style

$ 379.00

The Neumann KM 84 is one of the most popular small-diaphragm microphones in history. We have cloned and upgraded its circuit, and developed a capsule that recreates the sound of the original—within 1dB from 80Hz to 20kHz:


Our capsule is a bit more open at 10kHz than Neumann's, but much closer to the original KM 84 than is Neumann's current production KM 84 replacement, the KM 184,whose +2dB presence peak from 7k–12kHz has ensured that vintage KM 84s remain highly sought after (and highly priced). Said another way, engineers strongly prefer the more neutral voicing of the original mic, so that's what we recreated.

What's in the box

This is a DIY microphone kit; it requires soldering, wiring, and assembly. If you'd like to buy a finished microphone, contact us via email.

The kit includes the capsule of your choice (cardioid, hyper, or omni), complete metalwork, our custom KM84 circuit board, and all the components needed to build the mic. The build manual is a 32-page book with color photographs and step-by-step instructions; it draws on nearly 10 years' experience making the best assembly guides in the DIY industry (according to our customers).

Single mic kits include a shockmount. Stereo kits include two shockmounts and a flight case.

Customer Testimonial

"The sound is incredible! Using this mic with an LA-610, the mic sounds incredibly warm like what I would expect from a KM54 or similar SDC tube mic. A lot of detail but a gentle roll off at 10K makes the mic have very useful detail without too much high end extension that would make it sound more tinny. I think the transformer is what gives it the thick, tube like sound. I have been favoring mics with built in transformers lately and have been more appreciative of what nice color good transformers add to mics and preamps.

"I have previous experience with modded [brand redacted] mics which are also trying to go for a KM84 sound. I think this kit produces a much higher quality mic than even the most tricked out [redacted] which is around the same price as the kit. Ultimately I sold the [redacted] because I always preferred a bigger LDC sound for vocals or overheads. Now that I have this mic I think my problem wasn’t with the small diaphragm of the [redacted] but the small sound it had. I can’t say enough good things about the sound!

"From initial tests I think it may become my vocal mic - I’ve been through a lot of mics trying to get the right sound. Warm and intimate, detailed but not too bright. Probably kills on overheads but I’d need to get another one for that!"

Capsule Options

Choose Cardioid, Hypercardioid, or Omni. If you're not sure what you need, choose Cardioid, which is the most popular and most commonly used.

The Hypercardioid capsules exhibit nearly identical frequency response to Cardioid, with 5dB better rejection at 90 degrees. Hypercardiod capsules also have slightly higher bass response than Cardioid.

About the case

The case is included for free with the purchase of a stereo kit.

We designed the flight case to store two microphones and two mounts. A fifth die-cut provides for future expansion (e.g., Cardioid, Omni, or Hypercardioid capsules).

About stereo pairs and matching

If you purchase a single microphone kit, we cannot supply a match for it later. Customers interested in a matched pair should purchase the matched pair. Related: we do not expect to sell mounts or cases separately.

About the donor mic body

The included microphone body was manufactured at the same Chinese facility that produces a commonly used SDC donor mic. Although we QC them extensively, we note that most of these bodies exhibit a minor machining flaw, in that the three screws that hold the body sleeve onto the XLR housing do not exactly line up with the holes into which they are intended to match. This small mismatch does not affect the mic's usability, and certainly not its sound, but makes the final assembly step (namely, locking the body over the mic's internals) somewhat less precise than we'd like. We hope to create custom tooling for upgraded SDC bodies in a future production run, although that will likely add 20-40% to the cost of this DIY kit.


About the circuit

We understand the KM84 circuit intimately, because we've been using it for years.

This implementation employes a NOS JFET that is manually and individually biased for this circuit, using a signal injector and distortion meter. The JFET, and more specifically its operating points, are critical to creating the desired sonic character of this circuit.

There are exactly two capacitors in the audio signal path: a NOS styrene (film and foil) input coupling capacitor, and an Elna Silmic II silk-impregnated output capacitor. Both types are audiophile favorites, known for their wide bandwidth and clarity.

We use a custom-wound BV8 style transformer, made in the US, for this kit; it outperforms most other T14 sized transformers, and delivers a sound that has earned dozens of 5-star reviews for our LDC kits.

The circuit kit includes an optional feedback/pad capacitor. Leave it out if you mostly record quiet sources (acoustic guitar or strings, for example). Install it to increase the mic's headroom for recording moderate to high SPL sources such as drum overheads.

At the moment, this circuit is not sold independently. We plan to make it available sometime in 2019.

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