This is more of a physics question and not so much about the art, so I have posted to GQ.
An electric guitar signal is created by the vibration of a vibrating conducting string in the magnetic field of the pickup. So why is tone of an electric guitar so heavily influenced by body design? Solid body vs. hollow, for example. A lot of the tone on a hollow-body guitar is the vibration of the wood, but why would that make the electric signal sound more “acousticky”?
With hollow bodies and semi-hollow bodies, I think (but am not sure) that the vibration of the wood causes vibration of the pickup itself which then interacts differently with the string vibration than it would have. Solid bodies have less of this but more sustain.
Piezo pickups are another story, they work more like a microphone.
I can’t address the question, but I can tell you that it doesn’t stop at body design. Maple fretboards sound different from rosewood, for example.
Agreed.
Just go ahead and play an archtop guitar (like an L4 or L5) for awhile. The instrument sounds pretty darned good without amplification, and you can feel the vibrations in your gut when you play. So much of what we hear is the instrument’s own sound.
Now, when we plug into the amp, the vibration of the instrument is induced in the pickups, just like the string vibration alone is (what does the coil care if the string moves in front of it or it moves behind the string). So you get a melange of nice guitar vibrations mixing with string vibrations.
Then when you turn up the volume, the guitar now starts building up all kinds of feedback sounds, to the point where an archtop really isn’t the right tool for loud music.
And the strings… grab some flatwound 12’s if you want that smooth jazzy sound.
ETA: There’s a beautiful Gibson L-4 hanging on the wall at my local guitar store. Its siren song keeps calling me. Almost 4K though.
Semi-hollow electrics are my favourite kinds of guitars, but they don’t sound radically different to solid body electrics. An ES335 sounds very similar to a Les Paul, and in blind listening tests I doubt many people could tell them apart. (People have a habit of way overestimating their ability to hear differences in guitars.)
A fully hollow guitar does sound different, more “lively” but also more prone to feedback. The reason being that a hollow body has an effect on the way the strings vibrate, and that’s picked up by the pickups. It’s a kind of feedback loop. But a great deal depends on the player, the amp, and all the other variables.
A good example of those variables are the Who albums Who’s Next and Quadrophenia, both of which were mostly recorded with a hollow body electric. Do the guitar parts sound different to other Who recordings where Townshend uses solid-body guitars, such as the Tommy album? Yes they do. Is it a radical night/day difference? Not really. It all sounds like Townshend.
All a matter of scale. The bottom line is that the signal is the relative movement of the wire in the magnetic field. Both are moving. A mistake that is often made in simple thought experiments is that the wire doesn’t move all that much compared to say an acoustic guitar, and the rest of the guitar even less, and so it is only the wire moving that matters. But it is relative contribution of energy that is the total sound. Everything contributes.
Another point about contributions to the tone - it isn’t just the struck string that contributes - the other strings will too. If you strike one string, very soon the nearby strings will start to vibrate too - as energy is transferred to them. This transfer is mostly going to come via the bridge piece. So the physical characteristics of the piece, the manner in which it is mounted, and the material into which it is mounted will all modify the nature of the transfer. I suspect that the difference that body cap material makes to the sound mostly comes from this. Energy will of course couple down in to the body and into the pickups too. A hollow body will couple energy directly to the pickups more easily, and also reflect energy back into the bridge piece and into the strings in a characteristic manner.
Clearly playing with any serious amount of amplification and the body characteristics will make a huge difference as the sound couple back in to the guitar body.
This is a good point I hadn’t thought of. However, many archtops (like mine) have floating pickups that are intentionally mounted off the faceplate to avoid damping the vibration of the body.
It’s not just the design of the body that affects the sound but also the wood that it is made out of as well. As was mentioned, the sound goes through the wood, so you get resonances from the wood as well as a filtering effect. Softer woods will dampen higher frequencies and produce a “softening” effect in the sound. The pattern and size of the rings also affects how sounds of various different frequencies will pass through the wood. Some woods for example have hard rings but softer bits in between, where other woods are more uniform.
The combination of filtering and resonance gives the body a very complex frequency response. The construction of the neck affects the sound as well (as was already mentioned) for similar reasons. Maple is a fairly uniform wood, and doesn’t tend to affect the sound characteristics all that much, though it does tend to lose the low frequencies a bit. Rosewood, on the other hand, gives you a better sustain than maple, and does a better job of transmitting the lower frequencies through it, but it also tends to smooth out the higher end frequencies a bit.
One good example of just how complex this all gets is if you take maple and mahogany and use them together to create the body, as is done with the Gibson Les Paul guitar. Combined, the two woods have more sustain than either would alone. Also, maple alone is lacking in low end frequency response, which mahogany does well, and maple is more bright on the high end, which mahogany lacks. The combination is therefore far superior to either wood alone.
With hollow and semi-hollow bodies you have resonant cavities which affect the sound, as well as the wood itself transferring vibrations to the pickups. With a solid body you don’t have the resonant cavities, but the wood itself does resonate and affect the sound by vibrating the pickups through contact.
By adjusting the pickup height, you can affect how much of the sound comes from the vibration of the strings proportionally to how much comes from the body.
Yeah, the differences are a bit subtle, and if you just run the guitar through a bizillion effects or add a ton of distortion then you aren’t going to hear it. If you know what to listen for though you can definitely hear a difference.
I picked Townshend for that example precisely because he didn’t use effects. His setup with the Gretsch was guitar/lead/amp. My point was that guitar bodies don’t make nearly as much difference as guitarists imagine they do.
I agree. Given minimum standards of guitar quality, I think that who is playinghas more to do with the way the guitar sounds than most design differences. The only possible exception is the difference between single coil and double coil pickups. The difference is radical.
I have 14 guitars, and even though many are more expensive, my favorite workhorse is a semihollow neck-through Ibanez Artcore.
I like the amps loud, and getting easy feedback is something I want. I like to find that sweet spot where I turn my back to the amps, no feedback, but turn to the side and it starts…
Didn’t Ted Nugent do about the same? I’m not real sure about any effects, but it doesn’t really sound like it.
That’s one beautiful guitar!
I can’t imagine that the pickup isolates the vibration of the guitar much, unless it is suspended by some super unobtanium springs and such. Looks like a humbucker to me—those are what I have on my semi-hollowbody, and they move if I touch them, but just don’t have the flexibility to dampen vibrations much.
Of course, I have no real knowledge to base that statement on. For all I know, the Gibson engineers tweaked stuff so that the pickups dampen 85% of the guitar vibration… but then wouldn’t that detract from the sound?
And yes, I am envious of the full hollow body sound. My current jazz box is really a semi hollow body, and it lacks that full sound I’m looking for (though it still is a great guitar).
Everything contributes, but you would have thought that the contribution from the vibrating string is far more important than anything else. The reason I say that is that when you pluck a string, you can actually see the vibration easily with the naked eye. But you can’t see the body’s or pickups’ vibrations. They must be orders of magnitude smaller. In other words, if you somehow took away the vibration of the string, and just relied on the movement of the pickup to generate the signal, you would hardly hear anything.