Wednesday, September 27, 2006

Naked Eye Ribbon Microphone Review in October Sound on Sound

Sound on Sound has an excellent review of the Naked Eye ribbon mic in the October edition. Reviewer Hugh Robjohns takes a very detailed and mostly accurate look and listen in his article, which is accompanied by a two-page spread and an excellent photo of microphone and mount. Above you see Desiree taking a break from her busy day of building Naked Eye Mics here at the lab. Hugh Tripp best appreciates Robjohn's notice of what he calls the "surprisingly high standards of machining and presentation found in this mic". Hugh is an amazing machinist. A few excerpts:

"Excellent sound quality for a very reasonable price"

"cunningly tailored..."

"The naked eye mic is a delight to use. The stand adaptor is brilliantly simple, but effective.."

"The side nulls are deep and clean, and I was able to produce a remarkably spill-free acoustic guitar track from a singing guitarist..."

" can't have this one - it's staying here!"

Sound on Sound is an excellent magazine filled with much well written editorial material as well as the aforementioned quality photos (can we borrow your photographer?) This readworthy magazine is available by subscription online and in paper form, and at newstands. I suggest you go get it, or sign up here for your own subscription.

Tuesday, September 26, 2006

Hofner Verithin and a Speed Graphic

I get asked from time to time about my Hofner Verithin which is shown here and also on our contacts page. Here it is shown edge-on under the peering eye of the Graflex Speed Graphic which is a great old 4X5 inch press camera with a cool bellows and a huge flashgun. I've written about how to repair them.

The Graphic lens can be air actuated . That cylinder next to the lens is an air dashpot that can be used to push the shutter release via a rubber bulb and tube arrangement.

The Hofner has very well done kerfing in the F- holes, and at the periphery of the body. It has a carved top which supports the tremelo tailpiece with its die spring made from a GT6.

Monday, September 25, 2006

Herb Singleton: Cross-Spectrum Labs

An old trolley on the Riverside Line. You could open the windows, feel the breeze, even spit - something they do not want you to do anymore, for everyone's safety.

Trolleys are relatively quiet, compared to trains, traffic, highways, construction sites, airports, factories, machinery, jackhammers, automobile horns, jet engines, car washes and many other mechanized appliances of life in the 21st Century.

That's why Herb Singleton, owner of Cross-Spectrum Labs comes in. Herb is an acoustics engineer, local guy, MIT alum, who spends most of his working time making measurements of, evaluating, quantifying, reporting on, and recommending the mitigation of NOISE. He does this for commercial outfits that need to comply with the regs, and also for municipalities concerned about noise levels.

They should be concerned. Noise can be deadly, raise your blood pressure, cause important sounds to be missed, create fatigue and illness, and it is just plain annoying. Perhaps the definition of noise is any sound you don't like: In any case Herb is your guy if you need professional noise measurements, done scientifically, correctly and in an unbiased manner.

Herb also does mic measurements for Crowley and Tripp microphones and it is his measurements that you see in all of the spec sheets.

Check out Herb Singleton's blog on acoustics and things related. It's a fun read.

Thursday, September 21, 2006


Bob Crowley shakuhachi at an improv with Philip Lampe and Robert Manzke

I'd bet that many musicians know how their mood affects their playing and have learned how to control it to some degree. The shakuhachi seems particularly sensitive to mood, and the more I listen to the great players and try to imitate some of the tones and sounds they have recorded, the more I appreciate how mental state affects the quality of the sounds I do manage to pull off. The shakuhachi is sort of a dual-use instrument for music making and also for zen meditation.

A clear mind, relaxed breathing, positive attitude and the elimination of intrusive thoughts and external sounds are apparently the prerequisites that work for me. When I am alone I play briliiantly and when others are around not so well, so confidence is of course a big factor. Having confidence seems to be a mix of conditions, people and instrument and if I have a flute that I know is going to reliably hit that note, even if it doesn't sound as good as the better sounding flute, there's the importance of choice. You can see how musicians often choose their instruments and other tools based on confidence and peer consensus, and quite rightly so, as this is a definite boost in their favor.

I also find it helpful to have a distant view off to some far away hillside, which I am fortunate to have from my home which looks out over hill and dale, but I don't know why that helps.

It's intriguing that these minor external things seem to have such a strong influence on timbre. Tone in the shakuhachi and certain other wind instruments is developed and modulated by embrochure. The connection of the lips to face, the mind to mood and then perhaps facial expression extending to body posture and the subjective thought processes, applies to the meditative clearing of mental clutter and central focus on dimensions of sound.

I have Paul Kastner to thank for turning me on to the shakuhachi. Paul and I went to high school together in Newton, MA, and after college he moved to Japan, went to a Japanese music school where he learned to play the shakuhachi under a master, raised a family, started a woodstove business in Nagano, and returned for a visit with his shakuhachi. Today (or tomorrow - he's in Japan now) is his birthday - Happy Birthday!

Link to a shakuhachi-like device I made from a recorder.

Link to a shakuhachi recording session with Philip Lampe

Monday, September 18, 2006

Hand Made Crowley and Tripp Ribbon Microphones

Attention to detail, careful, artistic crafstmanship and finishing, and focused, individual evaluation go into every Crowley and Tripp Ribbon Microphone.

Hugh Tripp, shown above, deftly finishes an edge to a jewel-like appearance that marks the precision nature of the all stainless steel bodies of the Studio Vocalist, Soundstage Image and Proscenium ribbon microphones. Why stainless steel? Well, because it's hard to find a more durable, strong and good looking material, one that has the added advantage of great RF and magnetic shielding, and that can be designed to easily last a lifetime. That's good because these mics carry a lifetime warranty and have a design lifetime of 50 to 100 years.

You might have noticed that good microphones don't become obsolete very quickly. Plenty of old RCA microphones made 60 years ago are still around and operating. The key to such longevity is in material selection. Materials must be stable and not change over time. Certain plastics and rubber, and any electronic component such as resistors and capacitors, especially, change relatively quickly with age, sometimes over the course of just a couple of years. The reason for this varies but is mainly due to the hardening effects that occur as volatile materials slowly evaporate out of the material. Corrosion can play a role, and many plastics also can craze, bloom, delaminate and just plain crumble from exposure to oxygen and moisture. Heat can greatly accelerate the degradation of materials and electrical components.

Oily plasticizers are used in vinyl, which is a common wire jacket material. If you feel a mic cable and it's sticky, blame the plasticizers. Good cables use advanced polymers without the need for lots of silicone and mineral oils to keep them soft and pliable, but all of the cheap cables and wires ooze oil, some while still in the package. Naturally you cannot use anything that oozes in the screen or the housing of a microphone designed to last at least 50 years.

We don't like to worry, so we eliminate all materials that are likely to degrade over time.

You won't find gaffer's tape, foam or anything rubber in these mics, and even internal things as benign as solid steel are thickly plated with nickel and chromium. All of the Crowley and Tripp ribbon mics use solid silver contact blocks. This is done for two reasons: first, silver is a great conductor, and second, it plates easily with solid gold, which completely prevents tarnish and also has the advantage of making excellent, long lasting contacts with the ribbon materials, without corrosion and increases in resistance, which can lower output.

So when you see a Soundstage Image online or in a studio, imagine that mic at work in the year 2056. Minimum.

Rooster's Pair of Grampian Ribbon Microphones

If you've been following along, you already know about the Grampian which, in our case, was found to have decaying foam pieces in it after a long storage.

Such was also the case with blog frequenter Rooster from the UK, who purchased this beautiful red-labeled pair of Grampian ribbon microphones when they were new. I presume that was in the 1960's. He had made special leather satchels for his prized mics way back when, as the original red cardboard boxes they came in were too cumbersome. We have one of the boxes here, and it is indeed clunkier than necessary. After a short search, Rooster located the missing Grampians up in a cupboard. Upon close inspection Rooster also found crumblies inside, and managed to carefully clean them out. Now his pair of Grampians are performing once again, after many years.

I have asked and still do not know if there ever was a "Mr. Grampian" (or perhaps a Ms Grampian). If so, I would very much appreciate a picture of Grampian, the person. I have also heard there are some Grampian Mountains, somewhere in Scotland. Perhaps these are named after the not-so-famous pinnacles. I don't know. Something about the name Grampian reminds me of an episode from "The Goons".

If you don't know about The Goons, but like Monty Python's Flying Circus, you should check them out as they seem to have invented much of the silly humor that led to such gems as "Monty Python and the Holy Grail". robert j crowley

Friday, September 15, 2006

CW vs AM, Vinyl vs CD

Radio is a little over a hundred years old, and there was a period from about 1900 to about 1928 when radio was an experimental medium that hadn't reached the masses. But commercial communications and telegraph companies were making a lot of money sending messages across the Atlantic and elsewhere, and all of that communication was in the form of code: Morse Code, American Code, and other codes comprised of short and long dots and dashes. Originally generated by sparks, the on-off dots and dashes had a lot of noisy bandwidth and interfered with each other too.

It wasn't until the oscillator was invented that true "CW" or Continuous Wave transmissions - smooth notes of on and off - could be transmitted. These signals took up a lot less bandwidth and concentrated more power into a particular wavelength, or frequency. Whole industries grew up on the use of dots and dashes, helped along by a trained pool of telegraphers who already had been tapping out messages over Western Union wires strung along all the rail systems.

But the ordinary person couldn't much appreciate all those dots and dashes which sounded like gibberish and still do. It wasn't until the invention of the microphone that an audio signal could be superimposed over a steady, continuous wave, using a process still known today as modulation. The early modulators were carbon microphones placed in series with part of the oscillator. Since the oscillator had high voltage on it, you needed to keep away from the mic, or get your lips burned. There were a lot of shocks and "RF burns" in those early days.

The first modulation system was termed "Amplitude Modulation" or AM, as it varied the amplitude or strength of the signal according to the speech or music signal applied to the transmitter. This system is still in use, and some people believe it has a certain pleasant sound unlike that of FM or digital.

When AM first arrived, the old CW telegraph ops didn't like it. They were used to the dots and dashes which were music to their ears, so they fought it. When FM arrived, all of the static and noise common to AM broadcasting was gone, but certain people still thought that AM was more natural sounding than FM. It's easy to see the analogies to the tape vs protools arguments, and even the persistent vinyl vs CD dissonance. We know that innovation traditionally requires the disposal of some portion of the old that is cherished by those who have mastered it.

This year we celebrate the 100th anniversary of AM, apparently first used by Reginal Fessenden right here in nearby Marshfield Massachusetts, nex to the ocean. Fessenden's station "BO" (Bravo Ocean) was already in operation sending messages across the Atlantic in code, then he adapted the transmitter to do AM, and broadcasting began.

Here is a site dedicated to Fessenden's work, with a cool picture of his tower - a big one - at Brant Rock in Marshfield.
The tower is long gone.

Above you can see a more modern telegraph key that is still used today to do the primitive on-off keying to send signals across the ether. Why do people still do it? Why go sailing when you can hit the gas on your power boat? There's something about the economy and simplicity of "CW" to those who know the "code". In the middle is a crystal microphone from an old tape recorder I got on Christmas when I was a kid. Click on the image to get a good close up view.

Wednesday, September 13, 2006

Telefunken Spaceball Orbiting Microphone

Look at what I just got on ebay! This cool Saturn's ringed microphone from Telefunken. Who says that the old Telefunken folks were stodgy? This is far out!

Now I know what I'm gonna do with all those SM58 ball grilles I got at the flea market too.

I'm so excited.

Tuesday, September 12, 2006

Self Assembly

You might wonder about self assembly that all the nanos are talking about. Here's a photo of marbles that have been pushed together on a flat surface. As one might expect, the marbles settle in to the most compact form for spheres (or circles on a 2D surface).

Notice that every marble has six other marbles surrounding it. Since they are all the same size, which is very important, the marbles will always group into this basic hexagonal pattern. All circles, spheres, golfballs, carbon atoms want to do this.

The rules at the atomic scale however, are a little different. Here the hexagon is ruled by the physical contact to the mutually spherical surfaces of these relatively large, atomically speaking, glass spheres. With atoms, the charges and electron bond arrangements rule. Carbon atoms bond to lots of things including other carbon atoms, and can do so "at many places around their surface" if you could call it that. Being an atom is not like being marble, and the surface of an atom, or shell, is apparently comprised of orbiting subatomic particles called electrons.

Have you ever seen a marble made of marble? I have not, but I'm sure they exist and go back at least as far as the Classical Greek period and probably much earlier. Today, marbles are produced en-masse in marble making machines that spit out little dollops of red hot glass.

Gee whiz, that got me looking around for some marbles of antiquity - instead I came up with this informative site all about marbles. Cool.

Fire and Soot

A little heat is often all that is needed to soften metal and make it easy to bend and shape. The oxy-acetylene torch produces a very hot flame that will melt most metals very easily, and works on the principle of a hydrocarbon (acetylene gas) mixed under pressure with an oxidant (oxygen gas) which together result in a very fast, high energy combustion that makes lots of heat.

Here the torch is being used to bend some kind of prototype shock mount for a microphone.

Acetylene is also useful for making carbon nanotubes. Being a hydrocarbon, acetylene will decompose into individual carbon atoms - like a carbon gas - without burning, if you remove all the air from a heated chamber and introduce the acetylene carefully and slowly. I would imagine that an explosion could result if someone forgot to get rid of the oxygen first though I have not heard of any accidents like that in the nano-world, yet.

The heated carbon vapor will just deposit itself as a soot inside the chamber unless it has somewhere specific to go, and that's the trick to making carbon nanorods and nanotubes - you have to have a "seed" for the carbon atom to stick to. Then, amazingly, other carbon atoms seems to line up, almost all by themselves, into a neat circle and stay there, then more carbon atoms go around and around the circle, forming a tube that grows taller and taller.

It's called Self Assembly

So carbon nanotubes are, essentially, soot. Millions of chimneys probably have trillions of carbon nanotubes in them,. But it is a very special, organized soot that has a useful shape that can be used as an antenna, a sensor, a way to deliver a drug or chemical, even a way to strengthen other materials, like microphone ribbons. 

We are in the middle of The Combustion Age.  Combustion Age economics dominate our planet and our technology, the way we eat, move about, and live.

Precursor and early-stage Combustion Age practices and industrialization stimulate rapidly accelerated human population growth. Late-stage Combustion Age practices are severe and brief survival responses to population explosions on this planet.   The need for energy to power things is nearly universal, and a simple way to release stored energy for heat is to burn it.  The consequences of basing an industrialized society primarily upon Combustion are just starting to be realized by a few groups and thought leaders on Earth, but political democracies cannot much influence the root cause of accelerated combustion, which is overpopulation and resource depletion.

robert j crowley

Sunday, September 10, 2006

Nanoribbon and the Kiwi Connection

There are so many "Nano" companies out these days that I hate to even use the term. Nano has become the new in my opinion, flailing away in the capital markets with all manner of new and improved esoterica presumed to address nascent billion dollar markets. A google search will show you that there are already hundreds of products with "nano" in the names, yet very few to actually incorporate anything nano.

Of couse, nanotechnology has been around for a very long time. We used ot call it chemistry. Pigments, plastics, inks, cosmetics -- these are all nano and known for centuries. But the nanotech revolution revived what was a rather boring landscape of traditional chemical science, and now every chemistry department is "doing nano".

Naturally there are a lot of claims being made, and many patents being issued. Some larger companies such as NEC claim to have discovered carbon nanotubes in 1991, which is fairly recent. Numerous press releases recant the assertion that Ijima of NEC discovered carbon nanotubes, and the same sentiment gets repeated over and over in the academic press, too. This is the kind of thing where repetition results in accepted truth - say it enough times and it will be true! Now, I don't know NEC's Ijima, the person they give the credit to, but I am sure he is a very nice guy.

Which makes me wonder why John Abrahamson and Peter Wiles,chemists from University of Caterbury, New Zealand don't get the Nobel Prize for their discovery of Carbon Nanotubes in the late 1970's while we were all still in the grips of disco. I also wonder why so few companies and academic researchers have bothered to do the research that shows that the inventive Kiwis were way before anyone. MIT's Dresselhaus, et al, in this 1998 review article, seem studiously unaware of the work of Abrahamson and Wiles.

So anyway the ribbon microphone is also an example of existing nanotech in several ways. First, the ribbon is a microns-thin device and a micron is merely a thousand nanometers, exactly. Then there is the ribbon excursion, which is very much in the range of just a few nanometers, or billionths of a meter, yet enough movement to produce a signal that we can record. Remarkable. Even more, the oxide layers and the contact surfaces, all which make a difference in the sound of the microphone, are nanoscale phenomena. Because of the thinness of certain materials, there are interference effects that can render colors, such as a blue iridescence that can be seen. Tempting to imagine the name "Blue Ribbon" on this guy.

Saturday, September 09, 2006

Music Break - The Jealous Girlfriends

Check out Josh Abbott in The Jealous Girlfriends who will be appearing at TT the Bear's in Cambridge on Thursday, September 21st. Go to their website and notice the excellent choice of blog format, among other things, such as links to various downloads, some which I just listened to. Not bad I must say!

Worth investigating to hear what is coming out of NYC and playing in Boston.

What a Body

The CAD program SolidWorks makes it very easy to render these types of images which can later be used to make actual parts. One of the neat features is the ability to render shadows and reflections, which give some idea of what the part will look and feel like before actually committing cutters to metal.

This particular image is an improved look at the "South Beach" style microphones that we have been playing around with for a long time. These bodies were originally a disguise, intended to mask the look of the final product, and they were intentionally "art deco" to promote a classic impression, which they are not.

Sneaky eh? It's often important to separate looks from performance. Of course, if you see cheaply made unfinished surfaces or a lot of crackle paint which hides many sins, you might not have much confidence in the performance either.

People see not with just their eyes, but by their expectations and also with their fingers and hands. If something looks better when seen in person than expected, then the seen object is regarded more highly. It is hard to convey tactile characteristics in an image on a computer screen, though somewhat easier in a glossy magazine. Naturally your mind's eye is superior at assembling what you have seen and learned into some form of story that conveys the context of how the item might be used for your purposes.

Monday, September 04, 2006

Site Update

A little housekeeping this week.

Copyright Notice:

"Latest News from Crowley and Tripp's Lab" and "B-Bob's Microphonium Blog", entire contents, images and writing, graphical layout, artwork and source Copyright 2006, Robert J Crowley author, Soundwave Research Laboratories, Inc. Ashland MA USA. All rights reserved.

The artistic design of all Crowley and Tripp microphones, packaging and labeling: copyright 2004, 2005, 2006 Soundwave Research Laboratories, Inc. All Rights Reserved.

Others are encouraged to link to postings on this site.


The following are trademarks relating to microphone products of Soundwave Research Laboratories, Inc:

Crowley and Tripp
Naked Eye Ribbon Microphone
Studio Vocalist Ribbon Microphone
Soundstage Image Ribbon Microphone
Proscenium Ribbon Microphone
Recordist Ensemble Stereo
The "bikini" logo is a trademark of Soundwave Research Laboratories, Inc.

Friday, September 01, 2006

RCA BK5a Inductors

While we're on the subject of ribbon microphone transformers, here's a shot of the inductor set found in the RCA BK5a ribbon microphone.

The can on the right is the actual step up transformer and you can see the larger primary wires that extend through the mic body to the motor unit and its ribbon. To the left, the low pass filter reactor can be seen. This is routed to a switch mounted in the base which can be turned with a screwdriver to switch in a bass cutting shunt reactance. The transformer is the bottleneck in ribbon microphones. An inefficient, poorly designed transformer will lack bass, lack definition, and develop a weak output that is easily loaded down. Ohmic loss can be very high, relatively speaking, in small transformers such as the one shown above, which contributes to the low output that many old school ribbon mics suffer.

RCA was right to encase these in cans, but failed to provide a low Z path to signal ground, which would have reduced RF pickup significantly. Also, the orientation of the transformer in the microphone case is important: A ferrous microphone case should have the transformer mounted 90 degrees from the long axis for best hum rejection in any direction.

Weak bottoms

The materials used in the transformer are critical for good signal preservation. The core material (if used) must not contribute to loss, nor should the inductance represented by the windings and the primary to secondary, and turn to turn capacitance be permitted to be uncontrolled variables. The transformer must be properly matched to the ribbon. This is not nearly as simple as it seems - the usual "less than an ohm" assumed ribbon Z is not very pertinent to the real dynamic Z at various frequencies, nor is it very useful to calculating the critical damping factor of the primary-ribbon system. Many old school makers used to apply loudspeaker resonance tests to transformer coupled ribbons. This practice is obsolete, as it assumes that there is a significant acoustic response correlation with the electrical resonance point, often in the range of 30-50 hz. Attempts may be made to tune transformer inductance so that the electrical resonance occurs at some set point, which further exacerbates the loss problems, often resulting in weakness in the bottom end.

We have found only a weak correlation between the electrical resonance point in transformer- coupled ribbon microphones and the actual acoustic response around that electrical resonance point. In other words, factors such as the local acoustics in the near field, ribbon motor geometry, and realized impedance at the ribbon-primary junction are far more important than measured electrical resonance as a function of impedance. A strong, clear bass signal requires efficient transduction of acoustic energy, which is largely governed by accurate physical ribbon motion inside the motor unit. Once this motion is developed and converted into a signal, the role of the transformer must be to preserve the signal throughout the frequency range without excessive loss.

Here is some more about the BK5a.