Hello to everyone, including those who’ve long been acquainted with Experimental Musical Instruments and those who are new to us. Here’s an update of goings-on at Experimental Musical Instruments as of late March, 2012.

Life gets busy and I rarely get around to posting anything here on the Experimental Musical Instruments news page these days. The lack of posts is certainly not because there’s no news; there are always good things happening in the world of inventive instrument making, and usually at least a few interesting things happening here in the Experimental Musical Instruments office as well.

But I’m back at the keyboard for the moment, and I’ll take the opportunity to write about an instrument I’ve recently made with one of the products we sell. 

The product is the small, inexpensive piezo films, the one-inch ones sometimes called piezo tabs, manufactured by Measurement Specialties Inc.  These little films have a thin layer of piezo material sandwiched between two layers of protective plastic. They’re typically used as contact pickups: attach one of them to a soundboard or other vibrating body with adhesive or double-sided tape and it will convert the board’s vibration into an analogous electronic signal which can be sent to an amplification system. 

When you first wire up one of these little films, before attaching it to an instrument, it’s quite natural to give the film a little flick of the finger just to make sure it’s wired properly and the signal is coming through. I’ve noticed that the resulting sound is kind of cool.  It’s a quick, percussive thump, but with a penetrating sort of resonance.  And it makes a difference how you hold the film while flicking: hold it near the end with just a bit of film extending out freely and it will produce a higher tone; hold it near the base with a longer overhang and the tone is lower.

Naturally this suggests a musical instrument. I designed a system for holding a row of twelve of the film tabs in a one-tier keyboard-like configuration in such a way that the overhanging length of each tab is easily adjustable. The outputs go to a little onboard mixer/preamp velcro’d to the body of the instrument, and from there to a regular musical instrument amplifier.

That’s really all there is to it, but a few more words about the preamp are in order. Two facts about the piezo films come into play here. One is that they produce an extremely high-impedance signal that doesn’t do well with long cable runs, tending to lose strength and fidelity. So, if the playing situation may call for a long distance between the instrument and the main mixer or amp, it helps to have the onboard mixer/preamp which takes the original signal and converts it to lower impedance before sending it on its journey. The other fact is that the piezos suffer a loss of signal strength if you wire too many individual piezos together. With the little onboard mixer, instead of joining the output from all twelve together I was able to join them in smaller subgroups and send them to different mixer inputs.  The mixer buffers the groups from one another and solves too-many-together problem.  The mixer I used (a model called MM-141 made by Nady) has four inputs, so I was able to group the twelve piezos in threes. It also conveniently allows for local volume control and balancing between the subgroups. Little mixers such as this have become fairly affordable and widely available. Within the subgroups, the piezos are best wired together in parallel, not in series.

I’ve now fooled around with the new instrument a bit and even played it once in public. The variously pitched popping sounds make a distinctive addition to any musical stew; standing out without crowding.

I recall that I came up with a good name for the instrument immediately after making it, and now I can’t remember what it was.  Let me know if you have any ideas.

A lot of people disparage the US Postal Service; I’m not one of them. They provide a remarkably dependable service in a remarkably hassle-free manner at a remarkably low price.

But once in a while, inevitably, those prices go up. The latest postal rate took effect January 24, 2012. Happily for our U.S, customers, we find we can absorb the increase and continue charging the same flat rate shipping fee we’ve been charging on orders shipped within the U.S.  But with reluctance we are rasing the shipping rate on international orders. The flat rate for standard orders will now be US$12.50 for orders shipped to Canada and Mexico, and $16.50 for those shipped anywhere beyond.

We ship most overseas orders by Priority Mail International. Of all available overseas shipping options, this service is by far the best blend of dependability and price, with the emphasis on price. The new US Postal Service cost for shipping their small flat rate boxes to Canada is $12.95, and overseas is $16.95. Just to be nice, we’ve set our new shipping fees a little below that. Thus, you get a fair price for shipping on small orders. Meanwhile, on bulkier orders you get a great price, as we still charge you the same flat rate despite the larger shipping cost we pay.

A moment ago I said that priority mail gives us the best blend of dependability and price for overseas delivery. Now a word is in order about the other half of that equation, dependability. With Prioity Mail and most other services, the US Postal Services delivers packages to the local postal service in the recipient country. The dependability of the delivery then depends on the quality of service there. The results vary widely from one country to another. With most overseas destinations, we’re able to ship with a high degree of confidence. For a others, it sometimes feels like a bit of a gamble. To reduce the risk of a missed delivery, we could use one of the private delivery services such as FEDEX or UPS. These services bypass local postal services, managing the delivery from our door to yours; they provide far better tracking and are generally more timely and dependable. But they cost much more than USPS, and I know from experience that customers definitely balk at those prices.  However, for those occasions when our overseas customers seriously need guaranteed prompt and dependable delivery and are willing to pay for it, we use a service offered jointly by the US Postal Service and FEDEX. In this service, overseas postal services are bypassed as FEDEX manages the overseas end of the delivery.  The service is dependable, prompt, and includes good tracking (and, of course, it’s quite a bit more costly).   This website is not set up to offer this option, but if you want it we can easily arrange it by phone or email.

A New Book Coming Soon from Experimental Musical Instruments

We’re currently working on a book-with-audio on the subject of weird stuff you can do to a guitar to get new sounds from it. “We,” in this case, is myself, Bart Hopkin, joined by the Dutch guitar maker and experimenter Yuri Landman.  Yuri’s an excellent collaborator for this project because he’s extraordinarily well versed in the field of guitar preparations, both in his knowledge of what others have done and in his own ideas and explorations.  And as co-authors we complement one another nicely, as he’s most familiar with the world of rock and electric guitar, while my original training was in classical and I’ve always done more with acoustic guitars.

What sort of preparations does the book cover?  Well, they’re quite wide-ranging.  Included are tricks for partially damping the strings, weighting them, adding rattles to them, crossing or snaring them, exciting them in unorthodox ways, adding middle bridges, bringing out peculiar resonances, adding percussion elements to the body of the guitar, manipulating feedback, using external radiation sources through the pickups, and much more. Most of the modifications and preparations discussed are easily put in place and easily removed. Some work best with acoustic guitars, some with electric, many with either or both.  Some produce raunchy sounds, some produce beautiful sounds, some produce comical sounds, some produce really strange sounds.    

The plan is to publish the book in print, with a generous complement of audio examples available to all online. We may also make the book available as a paid digital download, probably in PDF format. The work is coming along nicely at this point and we’re well on the way to completion, but I’ll refrain from giving a definitive date for publication.  Just keep an eye on this spot.

Experimental Musical Instruments is a very small business. In some respects it’s a one-man operation (although in other ways it’s not, since so much of what we do involves collaboration). But the one-man description does fit EMI’s office. That means that if I have reason to be off somewhere on other business, then there’s no one here to answer the phone.  So you may find, if you call here, that you get the message center rather than a real person. If you leave a message, I’ll try to get back to you quickly, and your patience will be much appreciated.

YES! (contrary to previous post)

 Some time ago, I posted some notes here on the question of whether the piezo films we sell will still work if you cut them to a smaller size.  What I said was, it can be done in some limited ways, but it’s not recommended because it will destroy the pickup if you snip in the wrong place.  It turns out that I was incorrect in some of my information, and trimming of the films is not so problematic after all, though there still are some caveats. This is good news for a lot of our customers, because there are many situations in which a slightly resized piezo is just what the doctor ordered. My thanks go to Joe Patrick in Michigan for recognizing the possibilities, investigating further, and getting back to me with better information. Here are the details:

In the earlier post I said that the end of the film opposite the lead wires should never be snipped off because, I incorrectly thought, this would break the electrical continuity between the two terminals.  It turns out that this isn’t true; you can snip the film any which way and it will still function. The important caveat is this: the films we sell consist of two layers of piezo material layered over with a protective plastic laminate, and process of snipping frequently creates a short between the two layers of piezo material.  When this happens, the piezo will not function.  To avoid this problem when trimming piezo films, snip cleanly with good, sharp scissors. Then gently smooth the newly cut edge with emery cloth or very fine sand paper.

Next, check the pickup to make sure it’s working. The easiest way to do this is to make a temporary hook-up using two hook-up wires with alligator clips on the ends (these alligator clip wires are available in electronics stores).  Clip one end of each hook-up wire to either the lead wires or the terminals on the piezo film. Clip the other ends to the tip and sleeve of the plug at one end of a standard musical instrument lead cable. Plug the other end of the cable into an amplifier input. Turn up the amp and flick the piezo with a finger verify that the sound is coming through. (If you don’t have alligator leads conveniently on hand, you can try other ways to make the temporary connection between the piezo and the lead cable plug, such as contrivances involving binder clips or clothes pins.)  

If the pickup is not working, turn off the amp, gently re-sand the newly exposed edge, and try again.   

When you’ve got the pickup working dependably, go over the newly cut edge with a clean cloth to remove any possible remaining particles there. Then tape over the edge with cellophane tape, creating layer or two of protection similar to the clear plastic laminate that covers the rest of the film.

Here at Experimental Musical Instruments, we use the United States Postal Service for shipping to our customers. There are several reasons for this choice. One is that for shipping within the United States the U.S. Postal Service has consistently proven to be admirably timely and dependable for us (contrary to the complaints of anti-government crusaders). Another is that its services are quite modest in cost, and we’re happy to pass these savings on to customers.

The story for overseas shipping is more complex.  The cost savings in shipping through the Post Office’s Priority Mail International service, as compared to private international shippers like FEDEX or DHL, are huge.  We’re able to ship a good percentage of our orders abroad for US$13.95 (that’s where our $14 shipping fee on overseas orders comes from), while shipping the same package with one of the private shippers would cost many times that at least. The problem is that the best that the US Postal Service can do is to deliver the packages to the recipient country’s customs service in a timely fashion.  That done, it’s anybody’s guess how long the package will take to clear customs. Some packages, we’ve found, arrive at the customer’s door halfway around the world in a few days; others take as much as a month.  The situation isn’t much different even when we use the Post Office’s more expensive Express Mail service.

And another drawback: more and more of our customers these days are requesting tracking numbers, which Priority Mail does not offer.  While Express Mail service does provide a tracking number, that number doesn’t do much to speed the package through foreign customs or provide detailed information once the package is in the hands of the recipient country’s postal service.

There is yet another level of service offered by the United States Postal Service in partnership with FEDEX. It’s called Global Express Guaranteed (GXG).  With this service, the US Postal Service delivers the package to FEDEX overseas, and FEDEX shepherds it through customs and does the actual delivery.  It’s a lot more expensive than our current $14, but still less than working directly with FEDEX or DHL would be.  The claim is that it offers good tracking as well as dependably timely delivery.  We are currently looking into this the strength of those claims. If it looks promising, we’ll consider offering overseas customers a choice of services – our usual, wonderfully affordable $14 overseas rate, with no tracking and the understood risk of delays, or a more costly but more dependable GXG rate. 

In truth, offering this choice will be quite a hassle for us. Revamping our website to offer a choice of shipping options will be a lot of expense for a business as small as we are, and managing multiple systems for order fulfillment will be a chore. But if difficulties continue with overseas delivery, the hassle will be justified.

In the meantime, our very affordable overseas shipping rates remain in effect, and we greatly appreciate our overseas customers’ patience in those occasional cases where delivery is slow.

This may be useful information: the countries where delivery tends to be slowest are Italy, Belgium and (surprisingly, for a neighbor) Canada. Deliveries to small developing countries also are sometimes unpredictable.

Over the last month or two this website had been getting increasingly slow to load and appear on your computer screen.  The problem steadily worsened, to the point where, during times of high traffic, it actually became difficult to access the site at all.  The problem was with our server, which had was doing a very poor job of managing traffic flow.  We’ve now upgraded and switched to a new  server, and you’ll find that the site now loads with gratifying speed.   Apologies to all for this frustrating problem, and thanks to our programmer, Frank Vera at http://verainteractive.com/ for speedy and competent fixes.

A few months ago I chanced upon news blurb posted somewhere concerning potato chip packaging. According to the article, the makers of the Sun Chips brand of potato chips had started selling their chips in an eco-friendly bag made from plant-based materials. Rather than lingering as litter in landfills for generations to come, the bags are designed to decompose into compost after a suitable amount of time. But high hopes for this excellent innovation were dimmed when complaints started coming in that the bags are way too loud! It seems they produce hugely distractingly irritating scrunching and crackling noises with routine handling. As a result, they are now being phased out.

Naturally, I was eager to hear what these bags sound like.  So I went to the grocery store and found my way to the potato chips aisle. There I found several varieties of Sun Chips which had already been changed back to traditional packaging, plus one flavor still in the eco-friendly, crackle-prone bags. I bought ‘em, brought ‘em home, and started scrunching and crackling.

And it’s true – these bags really are quite loud, and the sound has a crispness to it that’s more satisfying, to my ear than other types of scrunchable plastic packaging. Definite possibilities here for music and sound-work! But it remains to be seen how long the compostable bags will be available – perhaps they’ll be off the shelves entirely by the time you read this – and also how long an existing bag will retain its sound qualities before decomposition sets in.

 The term “acoustic amplifier” is sometimes used to describe sound amplification systems that don’t use electricity. I recently had some communication from Monte Thrasher on this subject (Monte is sound-adventurer/thinker/researcher, as well as visual artist, in the Los Angeles area). It got me thinking again about this rather fascinating topic. 

In the late19^th and early 20^th century heyday of pre-electronic inventiveness, several people came up with purely mechanical schemes for amplifying sound. Some of them worked in a manner analogous to electronic amplification systems that came later. In electronic tube amplifiers, a tiny electronic signal gives rise to a much stronger version of itself by means of a sort of gating system: through the use of vacuum tubes acting as gatekeepers, the relatively weak voltage fluctuations of the original signal are used to modulate the strength of a much larger voltage from an external source, thus recreating the pattern of the signal on a larger scale. A similar gating idea used in pre-electronic acoustic amplifying devices.

In the early devices, the external power source was compressed air. Imagine an air-gating system that can shut on and off the flow from a compressed air tank … or from a blower of some sort, or even human lungs.  If you can get the gate to open and shut at a frequency in the hearing range, then the resulting puffs of air will create an audible tone. If you can get it to open and shut in a pattern analogous to the wave form of a given sound, you’ll get a replication of that sound. In this way, the relatively small force required to operate the gate can be used to modulate the much greater power of a strong compressed air source, creating a stronger sound. Very clever!

Sound waves in the air typically have small amplitudes (the back-and-forth motion is small); and the force they exert is weak and diffuse. The same is often true (though a bit less so) for the vibrating bodies that generate those sound waves. So if you are to use these sources to operate an air gate, you’ll need to create a gating system that requires very little power to operate.

Let’s think about this: how can you create an air-gating system that requires the smallest amount of movement to let through a substantial puff of air? If you think in terms analogous to a garden gate or doorway, or even a faucet turning on and off, you’re not going to do very well – too much motion required to create an opening of any size. Somebody thinking about this in the early days came up with the idea of a dual-plate grid system. Imagine two flat, rectangular plates, perforated with identical grids of small rectangular holes. When the two plates are placed squarely one in front of the other, the holes line up and air is free to pass through.  When one plate is slid a bit to the side, the holes no longer line up, blocking the flow-through. If the holes are quite small, the amount of sideways motion required for blockage is small; yet if the number of holes is large, the amount of air allowed through when they line up can be substantial. With this approach a clever fabricator can create a gating system that allows a powerful air flow, yet requires relatively little force or amplitude of movement. And notice that this is not a simple on-off system; it’s capable of gradual closure and closure to varying degrees. This suggests that, in theory at least, it should be capable of reproducing the wave forms of the original signal with some subtlety.

Of course it helps to capture the strongest possible signal to begin with, since a stronger signal is more likely to have the power to operate the gate effectively.  This leads us to a question which perhaps should have been our starting point: what sound sources were these acoustic amplifiers being used to amplify … and, for that matter, what could they be used to for today?

For starters, acoustic amplifiers of this sort were workable with the phonograph disk sound recording systems of the day.  In these systems, most readers will know, the sound waves of the sound-to-be-recorded were captured by a diaphragm, whose motion in turn was transmitted to a stylus. The stylus was used to carve a wavering groove in the surface of a rotating disk or cylinder made of soft material, later hardened. (Notice that all of these pre-electronic systems faced the same problem: how to get the most, mechanically, out of sound waves that carry a minimum of mechanical energy.) For playback the process was reversed, with a stylus tracking in the groove and transmitting its motion to a diaphragm positioned at the base of a flared horn for projection into the air.  For a much stronger sound in playback, a similar stylus-based playback system could be used to operate the air-gate of an acoustic amplification system.

A system similar to first stage of the phonograph recording system could also be used for live amplification in real time. For this, the soundwaves of the sound-to-be-amplified were captured by a diaphragm, and the motion of the diaphragm used directly to operate the air-gate of the amplification system. 

Acoustic amplifiers were also used with musical instruments. I find this interesting to think about: long before anyone dreamed of making an electric guitar pickup, there were people anticipating the idea non-electrically. Many of these instrument amplification efforts, it appears from surviving information, centered on cellos and perhaps basses. These instruments are suitable candidates because their oscillating systems – the way the string drives the bridge and soundboard – are robust and forceful. The mechanism for transmitting motion to the air gate was attached directly to the cello or bass bridge.

So what did these acoustic amplifiers sound like?  Given a strong enough air source, according to contemporary reports, they could indeed be very loud; no one seems to dispute that. The sound, as reproduced, was accurate enough to be recognizable – e.g., speech amplified this way could be understood – but it appears that the frequency response was limited: great in the midrange, not so good toward the extremes.

You need links! Here’s a good article: http://www.aqpl43.dsl.pipex.com/MUSEUM/COMMS/auxetophone/auxetoph.htm

And to actually hear a phonograph with compressed-air amplification: http://www.youtube.com/watch?v=J7SV65DFNy8

 It’s tempting to think about the possibilities here for new musical instrument design.  I’ve long had an interest in instruments with forced oscillation. By that I mean instruments in which the vibration happens not because of the natural flexing back and forth of a string, membrane, bar or enclosed body of air, but because it is forced mechanically in some way. This could apply here: it’s not hard to imagine a gridded air-gate device with some sort of audio-frequency mechanical driver moving one of the grid plates back and forth.  This idea happens to be very similar to traditional sirens, which you can read about here:  http://windworld.com/features/gallery/musical-siren-built-by-bart-hopkin/. For such an instrument, in the tradition of wind instruments everywhere, human lungs might be a sufficient source of air flow.

Whatever the approach, there’s some fun to be had here with musical applications. Maybe some day I’ll try my hand at making something along these lines.  If you get to it before it do, be sure to let me know how it goes.