September 22, 2012

Q: In your book you recomend 30′ for a top radius, if one decides to buy a commercialy made disc. On the other hand I saw that James Goodall and Robert Taylor use 50′ and 65′ radiused dishes and Jim Olson & Kevin Ryan make FLAT non-radius tops. Olson said that he feels that these produce more responsive tops. So why, exactly, do you recomend a 30′ one? Wouldn’t a 65′ one be better since it is closer to being FLAT?

A: It’s a question of balancing various factors — very similar to a cook’s gauging how much of this and/or that spice or flavoring to use in making a dinner.

In the guitar (instead of carrots, lamb, and oregano) the ingredients are the string tension, the torque from the bridge, the mass of the braced top (which is arrived at by any combination of top thickness and bracing mass), top bracing and reinforcement (that is, the pattern and layout of the braces, as well as their profiling and height), and desired target sound (the resultant mix of monopole and dipoles, as well as sustain and dynamics).

There is no “correct” way to make a guitar. If there were, they’d all sound the same — just as if there were only one recipe for making French onion soup: then all French onion soup would taste exactly the same. In the biological realm, it would be equivalent to having every wife, husband, boyfriend, girlfrend, son, daughter, etc. be clones. So let’s forget “the one best way” of doing something complex.

Jim Olsen holds that a flat top is the most responsive. Very well. But what, exactly, does that mean? Does this not have something to do with how thick and/or stiff the top is, or how it is braced? And how it responds to the mechanical pull of the strings? I suspect that it does. So if we were to imagine a VERY thin top that is made flat, it would be easy to imagine it buckling or caving in under the pull of the strings… unless the bracing were beefy enough to make up for the weakness of such a flat plate. In other words, you could make that flimsy face hold up by adding more reinforcing.

You could also/instead make that flimsy face hold up better by putting an arch or dome into it. Arched structures are stiffer and more stable than flat ones — just as a pointed or arched roof on a house will hold up to rain and snow better than a flat one. Western architecture took a mighty step forward when structural doming became possible: the materials themselves — rather than supports, trusses, beams, and buttresses — achieve the required structural integrity, Analogously, if you put a dome or arch into the guitar face, you could use less bracing and achieve the same stiffness with fewer materials (i.e. less mass).

Less mass is good; it means that the strings have to strain less to coax sound out of the top. The strings need to work harder to get sound out of a heavy top — exactly as a horse has to pull harder to make a heavily loaded wagon move. You can appreciate that different archings/domings induce different amounts of stiffness into a plate. As can different thicknesses of that plate. And so can different sizes and layouts of braces. These are, in fact, the three main ingredients of top-making, exactly as flour, water, and eggs are three main ingredients in bread making. And in both guitars and bread the ingredients can be mixed or combined in different ways to produce a successful product. In the guitar this goal is: a top that is intelligently constructed and reasonably lightweight (which goes to sound), and also able to hold up to the pull of the strings (which goes to long-term stability of the guitar).

In the guitar, ridiculously small (or small-seeming) amounts of these various ingredients can make a difference you can clearly hear. For instance, a bit more or less top thickness can offset a bit more or less doming. A bit more or less bracing can offset a bit more or less top thickness. And so on. Identifying and using only one of these factors as being “most important”, appealing though that idea is, turns out not to be realistic. If the guitar were a political construct rather than a mechanical one, then it would work best as a democracy in which every component is (not to make a pun) given its proper voice. To make one into a “leader” (in our sociopolitical sense of the word) is not what a guitar is all about.

September 22, 2012

I want to tell you about an interesting experience I had a few years ago. A good many of you out there may well be able to relate to it.

Some of you readers may know that I play flamenco guitar. Well, in the best Shoemaker’s-Children-Have-No-Shoes tradition, I didn’t have a good flamenco guitar of my own for a long time; I was playing a borrowed cheapo. So, with friends’ benevolent prodding to motivate me (but that’s the subject of another article), I decided to make myself my own guitar. And I did. With great eagerness and anticipation.

When the moment finally came to string it up and play it, I was struck by what a magnificent bass response it had. My shop was then in a high-ceiling warehouse space, and this guitar’s bass absolutely filled that cavernous room. It made the air space resonate. It was like a Taiko-drum guitar. The bass was, in a word, simply awesome. It entirely overshadowed the treble end.

Unfortunately, a really good bass is not the sound that a good flamenco guitar needs to have. One wants something bright, zingy, penetrating, with the traditional flamenco rough edge. Where had I gone wrong? (Does this scenario sound familiar to any of you?) Technically, I’d built a guitar with a kick-ass good monopole, but not much cross- or long dipoles — although this was language I was to learn later; I was not familiar with such concepts at the time.

I spent some time pondering what to do. Shave the braces? If so, which ones, where, and by how much? Should I sand the top thinner? Again: where and how much? Should I put on higher tension strings? Or install a new fretboard with a longer scale? Or perhaps become withdrawn, eat compulsively, drop out of lutherie and realize my life’s secret ambition of becoming the first Hungarian-American sumo wrestler? Heck, I had lots of options. It also occurred to me that I could call some of my expert fellow luthiers and get some informed advice. It seemed, at least, a good way to get some consensus as to where to start. They’d know exactly what to do, surely.

I called noted authority Richard Brune; he not only makes classic and flamenco guitars, but is also a skilled flamenco guitar player. He’d certainly know how to fix this. So I described the guitar to him over the telephone, taking care to be as specific as I could be about sizes, measurements, thicknesses, etc. He took in my information and immediately told me that my braces were inadequate to the job; I needed much bigger braces. He advised me to rebrace the guitar in that way, or at least retrofit meatier braces in through the soundhole. I thanked Richard for his advice and hung up.

I’d hoped for an easier fix than to either futz blindly for hours through the soundhole; or retop the guitar; or remove the back, rebrace the innards, and then replace the back and then do refinishing. That’s a lot of work. Besides, it wasn’t as though the guitar were for an important client or anything. So I thought that I could perhaps get a second opinion — to at least force me to do this work by the sheer preponderance of advice. I called Robert Ruck, an internationally and deservedly noted Spanish guitar maker who also plays flamenco guitar. I’d known him, as I’d known Brune, from any number of G.A.L. conventions, private correspondence, phone conversations, etc. Many of you reading this will have attended their lectures, read their articles, and also met them.

Once again, I went through the process of describing my guitar to a knowledgeable expert; same guitar, same measurements, same parameters, same conversation. Robert took my information in, and just as quickly as Brune had given me his opinion, rendered his own: my braces were too big. According to him, I needed to shave the braces down drastically in order to gain a satisfactory sound. He offered to fax me a drawing — which he in fact did the next day — of a special brace-shaving tool that he’d invented for shaving hard-to-get-at braces through the soundhole; it was especially useful for shaving down the Spanish guitar’s diagonal braces — the chevrons that are farthest from the soundhole and the most impossible to get to. I thanked Robert for his input and hung up.

I’d hardly expected to get identical input from two independent luthiers; but this was ridiculous. My next idea was the obvious one: to call someone else and at least try for a consensus of two out of three. I needed more input. Whether I wanted it or not.

I happened to have a conversation with luthier Steve Klein the following week. Steve doesn’t make flamenco guitars — or conventional guitars of any kind, for that matter. Still, he’s a very smart, articulate luthier and a brilliant designer with years of guitar making experience behind him, so I mentioned the two conversations I’d already had about my guitar’s spectacular lack of tonal balance. I thought that Steve might have a useful perspective on my problem; after all, bass is bass and treble is treble and a guitar is a guitar, right?

Steve’s opinion, diplomatically rendered after I described my situation to him, was that my bridge design was faulty. In Steve’s opinion, I could improve the sound of my guitar in the desired direction by replacing the bridge with — I forget which now, since so much time has passed since this conversation happened, and I was a little shell-shocked anyway — either a lighter one or a heavier one. I thanked Steve for his input and said goodbye.

Armed with all this advice and support from some of the more prominent of my professional colleagues, I was, how shall I say it, not yet quite fully enlightened. The thought of hacking wood away from my guitar — or gluing wood on — here and there, hoping to strike gold through luck as much as skill, didn’t have much appeal for me. And, suppose I managed to destroy the bass response without improving the treble? Or even (God forbid) even improve it?! I agonized. But, I thought: I am a professional, am I not? Bottom line: I still needed to get at least some clarity on this matter. Understandably, however, I found myself a bit reluctant to ask for input from anyone else.

Right about that time I visited nearby-based luthier Randy Angella’s new workshop; Angella had been making lovely and really good sounding classic guitars for years, had then dropped out and gone into different work, and had more recently come back into lutherie. I thought I might get some ideas from him. But I wasn’t going to ask directly: I’d tried that tactic and it had been leading nowhere. I was going to sneak around and try to get a hint from whatever methods he was using.

Randy is a very nice man and is able to share freely of his knowledge and techniques. He was at the time making his guitar tops’ perimeters very thin — including the edge along the lower transverse brace, sometimes known as the harmonic bar; he was tapering the top on the bridge-side of the lower transverse brace, and leaving it full thickness past that brace. I took note of this. Unfortunately, as the wisdom I’d received to that point in time indicated that thinning the perimeter of a guitar face would loosen its “hinge” movement and help the bass, I couldn’t see that going in this direction was going to be of any help to me. I already had too much bass, and maybe I should have asked about Randy’s thinking. Bugfat.

I reviewed my options again. I could jump in and shave some braces. I could sand the top thinner. In both cases I’d simply need to figure out where and how much. I might have luck with higher tension strings; but they might make the guitar sound even more robust. Or lower tension strings: they’d give me a more delicate sound, surely. I could install a longer fretboard and scale; or a shorter one; this would be more or less the equivalent of experimenting with string gauges. I might dump the project and retop the guitar. Then, I could also leave town quietly. Yep, I still had lots of options.

I’d begun to get to know luthier Eugene Clark at about that time; he was living about fifteen minutes away from me. He and I got together at a local restaurant, after having had made on-again/off-again plans for some time. Eugene is almost legendary as a Spanish guitar maker, and, not surprisingly, the subject of my problematic guitar came up. Over coffee and dessert I described my problematic situation, and Eugene in turn explained his concept of the Spanish guitar to me: it is — in a nutshell — a thin film of lightly braced wood stretched over a spare framework of massive main braces that (1) strictly delineate its vibrating areas and simultaneously (2) sets the resonances of these areas by virtue of the level of introduced rigidity. As far as the face is concerned, Eugene’s idea of the most effective design is to have a thin, domed plate of topwood held up by a rigid perimeter and by rather substantial upper and lower transverse braces (i.e., the ones that straddle the soundhole) which are moreover fully anchored into the sides. That is, these braces aren’t scalloped at the ends — which weakens their attachment to the main structure, and hence their stiffening/load bearing capacity — but rather butted at full height against the sides, and then held in place on each end with a bracket. I showed him my guitar; Eugene immediately showed me something interesting: that by simply pressing on the guitar’s face with his thumb over the lower transverse brace, he could stiffen that brace — and the quadrant it served — sufficiently so that the tap tone became significantly altered. When he let go with his thumb, the original (and, frankly, thuddy and dull) sound came back; when he pressed down again, the top responded with a dramatically more live ping. No rebracing; no rethicknessing; but tightening the top up — even in this ad hoc and artificial way — made a difference that I could instantly hear. In dynamic terms, such a mechanical change toward brighter response would come at the expense of the monopole (which my guitar had in abundance); and it brought out more of the long and cross dipoles — which is exactly how a flamenco guitar ought to be functioning in the first place. I was very glad for this input.

In due time I went back to my workbench and reworked my guitar. I spent a day carefully removing the lower transverse brace through the soundhole. I did it carefully and cleanly. And I installed a meatier replacement. The toughest part was cutting the linings away; I had to do that to make room for a replacement brace that extended fully from side wood to side wood and whose ends I could glue brackets over. I had to cut two of my Japanese woodcarving knives’ handles way down to make the tools small enough to fit into the guitar’s body. I did a little brace shaving, but not much. Simultaneously, I did remove wood from the top selectively with sandpaper and a sanding block, so as to facilitate the dipole motions of the bridge. I reasoned that this additional operation would help further the phenomenon Eugene had showed me. Then I re-French polished the face.

It worked. I took this guitar with me to the next Healdsburg Guitar Festival — not to display, but to have and play after hours, to amuse myself musically. By then the guitar had settled in (as all guitars eventually do) and light reflecting off the face was revealing that the face was thinned to the point that one could see the “imprinting” of the braces underneath; I don’t think this had happened before; but the guitar hadn’t existed in its originally thicknessed state long enough for it to settle in, so I’ll never know.

Anyway, I signed up to do an open mic performance at one of the local coffee houses one of the evenings of the festival, and I played that guitar. To my surprise, a man came up to me after my performance and offered to buy that guitar from me on the spot. I’d never had such an experience before, and I’d certainly not expected to make a sale that weekend in such a way. But I did!

All in all, this had been a terrifically broadening experience, filled with surprises of all kinds at every turn. Lamentably, the world lost its first Hungarian-American sumo wrestler, but that couldn’t be helped. My thanks to all the people who helped me to learn something.

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This article has been previously published in American Lutherie magazine.

September 22, 2012

Q: Recently I bought your books & DVD and I found one sentence particularly interesting: you mentioned that if a guitar with a normal flat back had an arched top, its dynamics would be unique. Can you please reveal from your experiences in which direction the sound will change, compared to that of a normal flat/domed top?

A: It’s an interesting question, and to my knowledge no one has yet made a guitar like this. Mario Beauregard of Quebec, on the other hand, has been making something truly new: nylon string guitars with arched backs and flat tops.

The arching of a plate stiffens it: it improves its stiffness-to-weight ratio. And, acoustically, it raises the plate’s pitch: its vibrational behaviors are shifted toward high-frequency signal — such as the violin has. A small highly domed plate is not likely to have a good monopole — that is, a good low end. Also, the greater the arch, the shorter the sustain is likely to be.

Cellos have a low end, and they have violin-like arched plates — but they are huge compared to a guitar. So part of what we are discussing is the SIZE of the plate, in addition to its doming vs. flatness. But it would be difficult to play a cello-sized guitar.

There’s another factor too: what wood the arched plate is made of. Traditionally, all arched-plated instruments (violins, violas, cellos, standing basses, and jazz guitars) have used spruces and maples — spruces for the tops, maples for the backs. Maple does not have much sustain compared with some of the woods used in guitars, especially Brazilian rosewood (although, in my experience of the maples, Eastern rock maple has the most, Western broadleaf maple has the least, and European maple — which is a sycamore — has some). Therefore, if we’re talking about a guitar with an arched spruce top and a flat maple back, it would likely have a sound characterized by a quick attack and a quick decay: bright, brisk, zingy, sharp, and not much sustain.

Sustain is not a factor in arched-plate and bowed instruments. They don’t need natural sustain: they will make sound as long as the player continues to scrape his bow over the strings. In the guitar on the other hand, because it is a plucked rather than a bowed instrument, the sound stops as soon as the strings do — just as happens with the banjo, lute, koto, ukulele, mandolin, dulcimer, harp, or harpsichord. [NOTE: the harp and the harpsichord are both excited by plucking action; the piano is excited by hammering action.]

It’s not likely that these traditions had such acoustic considerations behind them. The science of acoustics didn’t yet exist, and early European makers would of course have used the woods available to them — in this case the European alpine spruces and maples. They were a long way from having access to imported exotics from the New World. Also, in those days, the cost of labor was cheap and the cost of materials was high, so a thick plate of an imported exotic wood (that you’d carve down into an arched surface, and in the process wasting much of the wood) would have been quite expensive, compared to a thin plate of the same wood such as would eventually be used on guitars.