RM-8 DIY Ribbon Mic Project
A Ribbon Microphone Reinvented
Hey, ribbon folks! Some time ago I’ve realized that I can’t fit my new ideas into a slim ribbon mic body design, like RM-5, RM-6 or RM-7 anymore. I needed more space to accommodate the elaborate ribbon motor and transformer designs I have been conceptualizing in my head for months.
Therefore, I dove into an adventure of designing a new microphone entirely from scratch, rather than creating an upgraded model on a foundation of existing projects.
So, let me introduce the new RM-8 Ribbon Microphone. Its main features are a motor with acoustic resonant plates for the extended HF range and a hand-made transformer with a Permalloy core and noise cancelling windings.
Project details and short videos are below 👇
RE-554 Ribbon Mic Motor
The Motor with Acoustic EQ Plates
The RE-554 Ribbon Motor has a unique feature, which was widely used in the golden era of ribbon microphones, but is almost forgotten nowadays – an acoustic resonant plate EQ
The plates create a buttery smooth acoustic boost in high frequency range, which adds the air and presence to the sounds without adding ANY hiss or harshness. In simple terms, it is an acoustic high shelf EQ with all the advantages, but no drawbacks.
The starting frequency and the level of gain are determined by the geometry of the plates – the transparency ratio and the distance from the ribbon.
Each RM-8 kit will be supplied with two sets of different plates for the broad variety of sounds. You can also use the motor without the resonant plates for the classical conservative ribbon sound.
Check out a couple of quick samples I’ve made. Neither of these recordings have HF boost added during post processing. The high frequency details you hear come purely from the microphone itself. Some minor compression was added to make the tracks feel a little produced for the “finished” flavor.
The guitar sample was recorded with an open-air assembly of motor and transformer, as you can see in the video. The drum sample was recorded with the first version of the body that added a bit of extra edge to the sound.
However, the final version of the body has virtually a zero impact on the sound due to wide windows and a carefully selected type of grill mesh. And yes, the grill can modify the sound a lot! It increases the acoustic resistance and acts as a low-pass filter if the mesh is too fine.
The Modular Sound Concept
The Motor Comes with Two Sets of Plates and Distancers
The RM-8 Mic is based on a “modular sound” concept. The RE-554 motor comes with two sets of resonant plates, as well as two sets of distancers.
With longer distancers the high shelf EQ starts lower, around 5 kHz, for bolder hi-mids. On the other hand, with shorter distancers the shelf start higher, around 8 – 9 kHz, adding air and gentle brightness.
As for the plates: bigger holes add less boost (around 4 – 5 dB) for the gentle effect, while smaller holes add more boost (around 8 – 9 dB) for the distincts HF shaping. And, of course, the motor can be also used without the plates for the traditional unaltered ribbon sound.
Moreover, you can design and use your own plates!
RTY-40 Ribbon Mic Output Transformer
A Noise Cancelling Dual-Bobbin Design
The output transformer of the RM-8 Ribbon Mic is a dual-bobbin design. You can think of it as of a crossover between bobbin and toroidal designs. Such topology preserves the best of both approaches.
The bobbins allow the precision CNC winding, where both coils are made virtually identical turn-by-turn. The perfectly matching geometry is essential for flawless noise cancelling, as two identical coils feature the ideal common mode rejection. Therefore, the EMI immunity in a dual-bobbin transformer can be even better than in a toroidal design.
The core laminations are made from Permalloy 80 – probably the best obtainable material for clean amplification of small signals. It is a composition of Nickel, Iron and Molybdenum. It features the extremely low distortion (barely measurable) and very low losses.
As you can see, the transformer is rather large and there is a good reason for that.
The bigger is the core, the fewer turns of wire are needed to obtain the required inductance – thus, the total length of the wire is shorter, yielding lower resistance. Also, fewer turns result in lower winding capacitance, improving the HF range.
Moreover, fewer turns allow using a thicker wire, dropping the resistance even more. The primary winding of the RTY-40 is below 0.02 ohms, while the secondary is below 3.0 ohms. These are the outstanding figures.
The downsides of the big core? Well, such transformer is damn EXPENSIVE. However, the huge advantage of being a small boutique manufacturer is that I am free to opt for the best available materials and techniques in my quest for the perfect sound.
RM-8 Ribbon Mic Body
A Part of The Acoustic Design with Resonance Damping
The body of the RM-8 Ribbon Microphone is designed to preserve the sound of the motor and transformer assembly as if they were used in an open air.
I first tried the same approach as with our slim body microphones, but the sound was notably affected when placing the parts inside. The acoustic function depends on openings, grill type and an internal volume. It appeared that what worked for a slim microphone didn’t work that well for a big one. Therefore, I had to redesign the body from scratch to make it as acoustically transparent as possible.
After experimenting with different options, I ended up using a “big window” design for the body of the RM-8. After several tests I’ve figured out that any grill with eyes bigger than 1.1mm didn’t produce any high frequency damping within the audible range.
Moreover, I decided to prevent any possibility of unwanted internal resonances that could potentially result in spikes at certain frequencies. This way I came up with an idea of using felt dampers on a top cap and above the transformer to eliminate any potential for the standing waves inside the RM-8 body.
I use the synthetic felt, which doesn’t deteriorate with time and keeps its volume and shape perfectly. Additionally, the laser cutting process melts the sides of the dampers preventing any fiber from getting loose inside the microphone.
Finally, during the assembly process the transformer gets wrapped in dense synthepone fiber, which provides the additional insulation from vibrations and adds extra dampening volume to prevent any possible resonances at lower frequencies.
The DIY Kit Includes Everything You Need
The RM-8 DIY Ribbon Mic Kit Comes with All The Parts and Three Hex Wrenches
All you need to build a high-end ribbon microphone is here. The RM-8 DIY Ribbon Mic Kit comes with:
- The stainless steel body, made from high quality tube with 1.5mm thick wall with our signature grinded finish. The grill is made from acoustically transparent stainless steel mesh that does not alter the sound
- The RE-554 Ribbon Mic Motor with two sets of acoustic resonant plates and distancers with all the required screws
- The premium grade RTY-40 output transformer with Permalloy core and noise cancelling dual bobbin design
- Synthetic felt padding for internal resonance damping. A piece of synthepone foam (not shown) for wrapping the transformer inside the body. It also serves as low frequency damper
- Three hex wrenches (allen keys)
Pre-Order The RM-8 DIY Ribbon Mic Kit Now
Be in The First Row of Pioneers who will Record with it!
- The RM-8 DIY Ribbon Mic Kit pre-order quote is 490.00 EUR, the free shipping is included to any destination worldwide.
- The RM-8 Assembled Microphone option is +100.00 EUR per unit
- The SM-50 shock-mount (as on photos below) is +35.00 EURper pc
When you place an order for two units, you will receive a matched pair – it is a free service, I don’t charge any extra for pair matching. The maximum pre-order amount per customer is four units, e.g. two pairs.
The regular price of the RM-8 DIY Kit will be 690.00 EUR. You save 200.00 EUR.
The RM-8 is a big project, so the ETA is longer than usual. All the pre-ordered microphones and kits will be shipped in January, 2027 latest. However, most orders are likely to be shipped way earlier. All the orders will be shipped on first-in-first-out basis – the ones who order fastest, get their microphones first.
IMPORTANT note for EU-based BUSINESSES: If you have a EU VAT number, please drop me an email with your order instead of using the button above and I will send you the payment details. EU individuals and worldwide customers, please use the button above 👍
RM-8 Ribbon Mic - Photos
Some Extra Shots to Please Your Eye...
