Bumblebee Pro Audio

RM-6 Ribbon Microphone Kit

$350.00

Full Kit
Step-by-Step Guide
Supported
Beginner

Description
Audio
Design Notes
Specs
Docs

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.

Features:

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)

Assembly Manual (Same as RM-5)
Getting Started With DIY

Rich Natural Sound

I built one in about 20 minutes and was so pleased with it I immediately ordered another after I ran it through it's paces Great for acoustic instruments and vocals. Yet to try them for room mics but know they will be great for that too!

Easy build / Sounds Great

First Mic I've assembled. Wasn't bad at all. Getting all the parts into the mic tube is a tight fight, but I figured it out. Will probably get a second for a stereo pair, plus I think I could build the second one much easier. Ran it through a Cloud Lifter into an Apollo x8 preamp, and it really sounds great on my acoustic guitar!

Easy assembly; great mic!

This was super easy to put together - maybe 20 minutes from opening the box to recording with it. It picks up my resonator beautifully, which can sound a bit strident through some mics. Off-axis rejection is excellent as expected.

RM-6. Incredible all around mic

The assembly took me around 1 hour for a matched pair of microphones. I would consider myself a beginner solderer (I've soldered cables for a few years on and off and have a decent setup) and this project was easy. As my first experience with ribbon mics, I was very careful, and constantly reminded myself to not breathe or blow in the direction of the ribbons. Sliding the ribbon motor into the frame was the most difficult part. It takes some 'finessing' and patience to not jostle too much. In the end, I think I was over careful, but I wanted to make sure not to mess it up. The online video and step by step written instructions are fantastic. THEY SOUND INCREDIBLE. I have some nicer condensers in my studio (that's all I have to compare-Lauten Clarion 357, c414/214, vintage sennheisers,) and was pleased at how they match quality wise and beyond. The stereo image in a Blumlein spread is amazing. Acoustic guitar, piano, vocal, electric guitar--this mic is Super Natural, no hype or harshness on highs. It picks up all the lows, rumbles, etc. Reasonably flat sound with a low cut on. I found it perfect for taming a brighter/harsher acoustic I have and a brighter piano. I tested through a cloud lifter to Apollo 8xp and then just the Apollo 8xp.

Good, just be careful

It was good, very straight forward, just exercise caution. I had a few moments of heavy hands and one moment of not paying attention and ruined the capacitor for the mic. But after getting it all put together and running right, It's a good mic, little heavy in the low end but nothing to bad, just an opinion of sorts.