Bumblebee Pro Audio

RM-6 Ribbon Microphone Kit


  • Full Kit
  • Step-by-Step Guide
  • Supported
  • Beginner

The RM-6 is Latvian microphone designer Artur Fischer's new flagship ribbon mic. The RM-6 achieves exceptional clarity and detail while maintaining the warmth and musicality that ribbons are known for. The RM-6's 1.2 micron ribbon is hand tuned and paired with a custom transformer for the lowest distortion and greatest presence.

Please read Artur's design notes for more details and check out the audio samples to hear the RM-6 for yourself.

To purchase the RM-6 outside of the US and Canada, please visit the DIY Audio Components Store.


  • RE-323 ribbon transducer made of 1.2µm Japanese aluminum foil and neodymium magnets
  • Custom RTP-28 toroidal output transformer
  • Microphone body machined in Latvia of hand-selected stainless steel and matte polished for Bumblebee Pro's signature finish
  • Custom XLR recepticle with gold-plated pins for decades of reliability

DIY Friendly

The RM-6 kit is accompanied by photo, step-by-step assembly instructions. It's a great kit for beginners, as the ribbon motor comes pre-assembled and there are six solder joints to complete. The required tools are a soldering iron, some solder, and a hex wrench (Allen Key) set.

Kit Includes:

A shock mount is not included. The SM-28 is sold separately here.

  • RE-323 ribbon transducer (pre-assembled)
  • RTP-28 transformer
  • Stainless steel microphone body and mounting hardware
  • XLR insert with gold-plated pins

What is the difference between the RM-5 and RM-6 DIY Ribbon Mic kits?

The RM-5 and RM-6 are two different designs, they just share the same type of body. The main differences are:

  • RM-5 is a big ribbon mic with a 2″ ribbon; RM-6 is a small ribbon mic with a 1″ ribbon
  • As is typical for shorter ribbons; RM-6 has less distortion and sounds more "natural"
  • RM-6 has a slightly flatter frequency response than the RM-5
  • RM-6 has significantly higher output signal level, at least +3dB higher than RM-5
  • RM-6 has much lower magnetic flux leakage; there is practically no attraction between two microphones standing side by side
  • RM-6 motor comes with a 1.2u ribbon, while the RM-5 motor comes with a 2.5u ribbon
  • RM-6 comes with RTX-28 toroidal transformer optimized for thinner foil gauges

Hear a pair of RM-6s in a Blumlein setup below. Check out more audio samples under the "Audio" tab above.

The instruments (and vocals) in these videos were recorded using RM-6 Ribbon Microphones in Blumlein setup. Switch to HD video for higher audio quality.

RM-6 Ribbon Microphone is the result of all the experience and knowledge we have gained during the years of manufacturing and improving our parts and kits. The development process of RM-6 took nearly two years starting from the first sketches and ending with the units of the first prototype run.

The RM-6 Ribbon Mic Kit features precision machined and individually hand-tuned RE-323 ribbon microphone motor with a 1" long ribbon made from highest quality Japanese aluminum foil and high-grade NdFeB magnets. The motor was designed with the help of magnetic flux analysis software in order to prevent the excessive saturation, reduce the flux leakage by around ten times comparing to RE-254 motor (RM-5 kit) and increase the flux density in the ribbon gap resulting in significantly higher output signal level.

The RTP-28 toroidal transformer of our own design tuned for the higher impedance of thinnest foils gauges makes a perfect match with the motor revealing the great presence effect and preserving the clarity of sound.

Bodies are individually machined by a local company from hand selected stainless steel tubing of finest grades with attention to the details and mechanically matte-brushed for our signature appearance. Our own original XLR receptacle is CNC carved right in the bottom cap and male XLR insert with gold-plated pins is included. The Bumblebee logo is engraved with a fiber laser, so it's nearly impossible to damage it.

-Artur Fischer, Designer
  • Acoustic principle: pressure-gradient
  • Polar pattern: bi-directional / figure-eight
  • Circuit type: passive
  • Recommended load impedance: > 2000 Ohms
  • Frequency response: 35 - 14.000 Hz approx.
  • Output connector: 3-pin male XLR
  • Dimensions: D 1.10" (28 mm), L 7.68" (195 mm)

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