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Thread: Luthier As Synthesist

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    Luthier As Synthesist

    I posted this on Vintage Rocker, but thought I'd post it here because the PRS folks are more expert than I am. This hasn't even risen to the level of a theory. I'll call it a postulate:

    As some here know, I'm heavy into studio work that involves a lot of synthesis. Most synthesizers create their sounds by taking a waveform (whether that's caused by oscillators or samples, etc.) and modifying the waveform with subtractive filtering. I'm used to creating sounds by using these filters, and after 25 years of working with them, I know how to create sounds from scratch, what the filters do, etc. Bottom line, I'm a listener, and a tweaker, when it comes to audio. I do a lot of sound design, and I think I almost understand it!

    Luthiers, working with woods for centuries, have learned how to alter the waveform in similar ways, but they don't use the same terminology. For example, a hollow body guitar is just a big resonator that accentuates and removes certain frequencies and partials like the resonant filter on a synth.

    On a subtractive synth, the filters alter sound by subtracting from what's in the waveform. There are also filters that cause a resonance effect to emphasize a certain part of the waveform but all it's really doing is amplifying one part of it, not adding something. This subtraction actually creates different partials or harmonics to stand out, to disappear, and so on, thus changing the timbre of the sound coming out of the synth. This is modified by ADSR envelopes and low frequency oscillators to give the sound some movement. The ADSR (attack, decay, sustain, and release) also play quite a large role in the note played. The ADSR envelope of a piano with its fast attack, short decay, long sustain, and immediate release is one of the things that our ear uses to differentiate that sound from, say, a violin at the same pitch, with its long attack, long decay, short sustain (after the bow stops moving) and release.

    The filters don't ADD anything to the waveform. They do their work by removing certain harmonics, partials, etc.

    I think the woods (and metal parts) operate in the same way on the vibrating string, and in the case of hollow bodies, on the resonating sound. These differences between the filtering job the species of woods do give us the sense that certain woods are "brighter" or "darker," etc. It's similar to a synthesist deciding between a Moog filter and a Waldorf filter.

    After having various PRSes and other guitars over the years, with various kinds of woods, fingerboards, trim and what-have-you, I'm going to postulate that the different pieces, woods, parts, bits and bobs change the sound of the guitars by means of subtraction, not addition (unless a metal part is rattling), much like a synthesizer's filters. The problem is that I can't test this scientifically; I've only been able to use my ears listening over the years to my own instruments for long enough to understand the sounds they produce. Still, I think it may be worth thinking about.

    There are those who say that wood type doesn't matter on an electric guitar. I don't believe that. Our guitars sound different from one another for a reason. And changing the woods does give one a different sound. Just play a DGT Standard and a DGT maple top, and you'll understand that. In fact, no two guitars sound identical, and every one of us has experienced that when we go guitar shopping.

    Example: Folks say that an ebony fingerboard is brighter. Well, no. Carefully listening, I think what an ebony board does is filter some of the midrange allowing the lower and higher partials to stand out. We hear this as brightness and a clearer pick attack, with maybe more string-to-string definition because there's fewer midrange partials (that we hear as "complexity") happening. Just as with a filter on a synth! We're not really hearing more high end. In fact, I think that rosewood may actually be less of a filter from low to high end. And there's faster note decay with ebony; it's marginally less than RW, seems a titch longer than maple, i.e. the ADSR filter is set a little differently.

    Again, this contributes to the clarity of chords. This comes about because of the filtering properties of the wood, not the additive properties. In fact, it's obvious to me now why jazzers and classical musicians usually have ebony boards on their instruments: they want the articulation that the ebony helps them attain. They don't need big, sustainy chords, they need shorter and less chunky stuff that decays more quickly so they can get more clarity from chord melodies, fast single note runs, quickly change inversions without muddiness, etc.

    It's my thinking that possibly maple tops filter the natural resonance and sustain of mahogany. Mahogany rings when tapped, maple does not so much. It's my postulate that what a maple top is doing is not adding brightness to the signal, but removing and damping the resonances of the mahogany just like a filter. The result is the removal of some midrange partials, changing the ADSR envelope, and we hear it as accentuation of the brighter partials that are already present in the waveform. This filtering/damping improves the articulation of the notes, but takes away some of the growl. And that's great for certain sounds we need, not so for others!

    This may be why f'rinstance Chris' demos of the DGT Standard sound so chunky and the DGT maple top sounds a little more articulate on the top end.

    Anyway, I'm not a scientist, just a synthesist, and these haven't even risen to the level of theories. Just up for discussion. Nor have I scratched the surface in this post, it's just something I've been thinking about for the last few days. When Paul Smith and company sit around designing guitars, they're synthesists!

    I'm not, repeat, NOT trying to convince anyone this theory is correct, just stuff to discuss and think about.
    Last edited by LSchefman; 08-11-2012 at 10:47 AM.

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