Industrial Design and Engineering of the RM1


“The Artist’s Microphone”

The RM1 microphone was designed, developed and engineered by pro-audio transducer inventor and technologist Cliff Henricksen.  Cliff’s “one foot on the bandstand, one foot in the lab” musical life gives a balanced leftbrain/rightbrain approach to creating useful, technically-advanced and beautiful-sounding tools for all artists in the sound arts.  The microphones are machined and assembled exclusively in America.  

The RM1 was created to improve on well-known qualities of "large-format ribbon microphones", namely low sensitivity (leading to a noisy processed signal), dull spectral output and difficult p-pop response.  

This microphone, we feel, is Beautiful, SuperQuiet® and Everlasting.  Here’s why:


   The RM1 sounds beautiful.

The RM1's diaphragm is made from exquisitely-thin aluminum.  It vibrates in a very intense magnetic field, creating unusually high output.  The diaphragm's output is amplified by a carefully-engineered and artistically-voiced, ultra-low-noise phantom-powered preamplifier, developed in collaboration with the LR Baggs Company of Nipomo, California.  This combination gives the user a true plug-and-play setup that rarely needs equalization, even in complex ensemble mixes.  The goal of “normal sound” (i.e., “high fidelity”) is a pleasant (and very useful) surprise to the first-time user.  Integration of “SuperQuiet®” technology assures sonic purity, free of unwanted noise (see below).  

The Grill and Pop-Filter System

A two-stage acoustically-transparent, non-resonant debris and pop/explosives filter system prevents the usual artifact of close-proximity pickup for vocals and instruments: 

First-stage, non-metallic, non-resonant protective grille of physically-tough, open-air, woven Nylon-Spandex™.

Second-stage, integral, internal, sheer-knit, acoustically-transparent pop/debris filter also improves lose vocal applications and added ribbon protection.            

Using an RM1, an artist can simply go to work and not have to think about “technical issues” involving sonic aesthetics (Equalization and p-pop signal overload). 


The RM1 looks beautiful

The RM1.  We think it has a functional and iconic beauty

The RM1.  We think it has a functional and iconic beauty

Aluminum case components are softened and matte-surfaced/softened as part of the manufacturing process and finished with an attractive but unassuming hard-anodize outer coating.  The first-stage grille is stretched so that it exhibits a graceful geometric form and pleasing color.  

The microphone was designed as a pure "Form Follows Function" creation.  On this subject, Cliff says: 

"You know, I'm not trained as an Industrial Designer or 'graphic artist'. I'm an inventor and a musician.  So when it came to the appearance of the RM1, I decided that presenting the microphone visually should be a very honest exposure and display of what the microphone really is:  I learned about this firsthand when my two sons and I built a 1965 Shelby Cobra 427SC replica.  That particular car had my attention since I was a teenager.  Just from the gut it appealed to me.  But when we actually built the car and I had more time to think about it,  it all added up a lot better.  I realized that all the proportions and air scoops and body-curves were not there to satisfy the results of some consumer-marketing focus group.  They were there because their creator (the late Carroll Shelby, driver and designer) put them there so the car would be a world-class competitor in automobile racing.  That's what made me love it.  It looked great because that's how it had to look to make it perform great.
So, I tried to apply the same rule to the design of the RM1.  I made it perform as best I could, finished it with the best finishes I could find and simply accepted (and appreciated) how it looked, for the most part anyway: The rounded case is a pure function of the optimization of the magnetic circuit.  You can actually see the ribbon and magnetic gap area inside the dual grilles. The rubber suspension elements look exactly like what they do.  That  grille bridge with the holes in it is designed so that the grille's shape deflects near-field vocal air better."  
"That pretty cool ''grille bridge''

"That pretty cool ''grille bridge''

The holes in the bridge prevent it from acting like an acoustic reflector.  The aluminum case surrounds and protects the magnets, clamps the main grille and is an electromagnetic sheild for the electronics.  But I'll take credit for the knobs.  I love them.  They feel great and they look right in proportion to the mic.  I looked and looked (and looked and looked and looked) and could never find a knob that worked for me.  Everything had the appearance of a Genuine Homer Simpson.  So I designed my own.  All done, I'm very happy with how the RM1 looks.  I showed the RM1 to a senior industrial designer I know who works for a large local company that markets to consumers.  He congratulated me on what he said was a 'balanced and good-looking ID'.  Interestingly enough, I also showed the mic to a well-known local artist who (like many) is a real gear-head and worshiper of ancient studio microphones.  He told me "...it looks like something out of the '50's, only brand-new out of the box.  'Back to the future' ":  not a bad impression. 

The knob :  Simple and easy to adjust

The knob :  Simple and easy to adjust


The RM1 feels beautiful  

          The softened, etched and anodized case components and knobs have a silky and friendly feel that invites the touch.  The first-stage grille, although “tough as nails”, has a refined, soft surface, especially as compared to typical metal-mesh grilles. 

          Using a Cliff Mics RM1 is a beautiful artistic experience - “The Artist’s Microphone” delivers sonic purity to delight the artist.  In most cases, simple level adjustment is all that is required to make a beautiful recording of any voice or instrument.  This is the paintbrush singers dream about.  Recordings reveal “the sound you hear in your head” (one artist’s reaction).  This microphone is superb for radio/tv broadcasting and for recording of many instruments including drums (NOT kick-drum), acoustic guitar, electric guitar amps, etc.  Its neutral appearance allows it to blend visually with any recording or visual broadcasting environment, looking beautiful without drawing attention to itself.  


The RM1 is SuperQuiet®  

RM1's Superquiet design philosophy improves its signal-to-noise ratio via increased gain and reduction of noise.  This is achieved via careful integration of design and engineering details and aggressive rejection of unwanted mechanical and case-modulation noise.  Typically, signal-born noise control becomes limited only by your studio environment. 

High Signal Level  

          A large-format corrugated diaphragm made of pure aluminum measuring 2” x 0.160” x 0.00007” is almost buoyant in free air, making it sensitive and responsive to changes in sound pressure.  Its size and geometry give well-known output benefits of high mechanical velocity.  An extremely-powerful magnetic circuit results in an unprecedented 1Tesla gap-flux intensity level at and around the ribbon.  This combination gives at least a 6dB boost in at-the-ribbon level compared to similar microphones.  

This is achieved via... 

Neodymium (NdFeB) permanent magnet sources, the world’s most powerful permanent magnetic material.  

(Cliff adds a note on this particular item...) 

"Remember that reference to Carroll Shelby 's Cobra in the Form-Follows-Function section?  It's amazing how that whole experience and sphere of consciousness has affected me and has resonated so strongly.  Shelby shocked the racing world of the day by dropping this tyrannosaurus-level NASCAR V8 engine into this ultra-light little polite English sporting-car, originally the AC Ace.  That's essentially what I did with the RM1.  Its two Neodymium permanent magnets are, for a microphone anyway, unprecedentedly-brutishly-powerful, requiring a lot of iron to conduct the magnetic energy to the ribbon, much like beefing up a drive-train to handle the power of Shelby's frighteningly-visceral engine.  It's like I dropped a fire-breathing NASCAR engine into what was formerly a 'normal polite ribbon microphone'.  In this way, the RM1 is sort-of the Shelby Cobra of professional microphones." 

A smooth, efficient magnetic-flow circuit components of n/c-machined pure iron.           

Optimization of all magnetic elements using advanced FEA (finite element analysis) computer-aided analysis. Compared to a racing engine, this is like "tuning it for maximum horsepower", making sure all the intake and exhaust ports are smooth and free-flowing, getting optimum fuel/air mix, etc. 

Graphic output from an FEA analysis:  A very good 2D approximation of the final 3D shape

Graphic output from an FEA analysis:  A very good 2D approximation of the final 3D shape

Low-Noise at-the-source gain

          A thoughtful and exquisite, zero-feeback, all-discrete preamplifier works off standard 48v phantom power and delivers a solid mic-level signal with very low noise.  LR Baggs engineers say they "used the kind of gain that makes the least noise" as the key.  Sounds duhh-simple, but it's actually not that easy to accomplish.  All this amplification is done at the ribbon, inside the microphone, allowing the RM1 to deliver a true differential signal at a level that often requires very little upstream amplification (the kind of gain that makes the most noise).  

LR Baggs preamp board, onboard the RM1

LR Baggs preamp board, onboard the RM1

Magnetic Boundaries create HF-Capture gain

          Boundaries of the magnetic circuit are physically-shaped to both make efficient use of the monster NeO magnetic energy and (as you'll read in this section) to improve the capture of high frequencies above 6 KHz.  This design detail creates improvements in sensitivity, capture of sibilance-detail and a more defined off-axis polar response in both directions.

Pickup Pattern of the RM1  

In many ways the RM1 picks up sound like any "classic" bidirectional large-format ribbon microphone (like, for instance, the ancient RCA44).  In the horizontal plane, full-fidelity pickup is acheived on-axis in both the front and rear of the microphone.  This allows the microphone to be used in many unique ways from instrument/voice recordings to multiple voice recordings to a unique integration of direct sound and ambient sound.  This is called a "figure 8" pattern and will do this for most frequencies.  Here's what it looks like for most frequencies:

 

The RM1's high frequency pattern, however, is unique to bidirectional microphones.  Because of the shape of the magnetic circuit in the viscinity of the ribbon, the pickup pattern becomes determined by the geometry of the sloping walls of the iron magnetic conductors.  These essentially create a "pickup waveguide" with about a 90 degree (+/- 45 degree) "hf capture angle".  Because of the physical size of this waveguide, the 90 degree pattern starts to narrow from the pattern shown above at around 3500 Hz and locks into the 90 degree pattern above 6500 Hz, continuing this to way above audibility on the high end.  Below is how the pattern would look at higher frequencies in either direction.  In black is the pattern as above.  In light blue are +/- 45 degree lines and in red is an approximate polar pickup pattern in the upper two octaves of the RM1.  

 

This more selective pickup actually improves the ribbon's sensitivity a bit and makes for a "tighter" hf sound in the upper two octaves, in both directions.  This is one of the many details that make the RM1 unique and unique-sounding.  Yeah, this is a little nerdy for most artists, so here's what this means to a user:  On a more operational view, if you can see the ribbon diaphragm in the horizontal (thru the grille/popfilter system), you get full hf sound.

Vertical pickup is another matter and is determined by a different acoustical mechanism.  The source size (the length of the ribbon itself) is about 2" tall.  By means of normal acoustical diffraction, the vertical pickup pattern will start to narrow from being very wide at low and mid frequencies to about 90 degrees at about 6500 Hz.  At 13 KHz, this will narrow further to about 45 degrees.  This is true for any large-format ribbon mic.   All this means is be aware this is happening.  And forget the numbers and graphs.  Listen, listen, listen.

Mechanical Dynamics-Engineering Reduces Mechanical Noise

          The 7.5# microphone body acts as an “inertial platform”, resisting noise caused by structure-born vibrations transmitted by microphone stands and support structures such as booms. This is also effective in rejecting LF/midbass air-borne acoustical modulation of the microphone body.  This can modulate the body of very lightweight microphones. For example, if the mic body were modulated by the incoming sound and had the same motion as its diaphragm, no sound would come out, or a weird out-of-phase effect would become part of the composite signal from the microphone. This could never fully happen, but it does happen on in a small way for very light-bodied microphones.  First-time pro users are impressed with the “solidity” of the RM1's sound.  We think part of this is simply because the sound only (and not the body of the microphone) influences the vibration of the ribbon.  This is purity of transduction. 

          The RM1's integral shock-mount further minimizes structure-born mechanical noise that will end up in unwanted audio signals.  Resonance is around 2 Hz.   

          Integral 24” (0.64m) cable assembly featuring industry-standard, low-noise/low-capacitance Gotham GAC3 cable, integral compression strain relief and gold-plated Neutrik cable-mount XLRM assures transmission of audio signals with full fidelity.   


The RM1 is Everlasting  

The RM1's materials and finishes are chosen for the long-haul: 

The pure iron magnetic circuit elements are plated with electroless nickel for elimination of any long-term corrosion threat. 

Aluminum case components and knobs are softened and hard anodized for an impermeable surface that never needs care, other than making the microphone look good with Windex® or other common cleaner.

Materials for other functions such as for fasteners and assembly materials; are chosen for archival longevity, such as stainless steel, brass, nylon/polyester fabric and pure silicon rubber.

The RM1 will stand the test of time, any environment and of course, daily use. 

Every mic has Cliff's Signature and best wishes for an enhanced artistic life using the RM1.

Every mic has Cliff's Signature and best wishes for an enhanced artistic life using the RM1.


It All Adds Up...  

Cliff's perspective on all this:

"After almost 50 years in the pro audio and musical-sound industry, I know we can't measure all the things we hear and perceive.  I also know, both from my own experience and from working with many , many artists, that the player's experience is both reported as; and  is in fact; a true, real experience.  Unfortunately it's also something that can't be communicated very well.  We really lack a good language for communicating such experiences.  All the details (a gazillion and counting) add up to the singular experience.  And so it is the same with the "recording artist"; the sound-artist, the human being crafting the recordings.  In the heat  and primordial ooze of the creative process, we all, of course, seek our best creative performance and we are all so immersed in it, so connected to it, that every synapse of our senses is locked into the work.  We hear and perceive stuff over our headphones or our monitor speaker, or inside our heart and soul, that no one else does or can perceive, because it is us that is doing the work of creating a beautiful recording, or the broadcast or the whatever.  So, when I'm doing creative work with the RM1, my personal reaction as well as the reaction of anyone else, is based on what we hear and feel at the moment or what we recall from  the moment.  This is the sum of all the effects of the details of the microphone I've discussed here as it creates a single signal from all the details of the performance being recorded.  Writing this, I'm astounded by the vast number of variables that contribute to our experience.  And so, the key to enjoying your creative life, like with the RM1, is to forget thinking about all this technical stuff and all the variables.  Forget it and enjoy the results from this unique instrument.  And, above all, enjoy the journey.  Do your work, have a great experience and make your best art."