Vibration and resonance isolation - practical?

[Ground Pounder]

I'm building a benchtop pickup and circut tester instrument for "the lab", and I got to thinking about vibration and resonance isolation and whether this could be practical for actual building and/or repair.

Looking at the basics of how an electric guitar produces sound, where a string vibrates between two points and that vibration is collected by the pickup and processed along the circut, it seems to me that this process can be isolated from the rest of the guitar using some type of absorbtion mounting of the pickup and string (meaning the bridge, nut, and fret). By doing so, you should be able to eliminate a great deal, if not all, of the sound influencers - namely the woods of the body and playing surface, and any modifications done to them which influence tone.

Now the question - why would you do this? Because (again, in theory) if you could replicate these five factors in isolation - string, pickup, bridge, nut, and fret - it would allow the rest of the instrument, namely the wood, to be simply cosmetic.

Of course, the key argument that comes to mind is that wood affects tone. While this is true, the devil's advocate in me wants to believe that by starting with a blank canvas, there should be a way to shape the sound around the five key components.

The second argument is that the player affects tone. I completely agree, and don't have any solution to this

I assume that somewhere along the line, this approach has been taken at least to some extent. And perhaps it's not practical for the modern instrument, given the extensive technology that's available from amp and effects manufacturers. But still... it's something I think I'm going to try, just for kicks...

... starting with my benchtop tester.

[David Schwab]

Now the question - why would you do this? Because (again, in theory) if you could replicate these five factors in isolation - string, pickup, bridge, nut, and fret - it would allow the rest of the instrument, namely the wood, to be simply cosmetic.

Stiffness is very important in instrument tone, IMHO.

There have been designs that utilize those concept you spoke of. One is the Bunker and Trecker basses and guitars. There is a steel rod running from the nut to the bridge. The neck attaches to that, and is pretty much free floating. This also takes all the tension off the wood of the neck, which they claim is beneficial, though I don't think the neck is adding much in this situation.

Other attempts at this idea are Alembic basses, where they wanted to isolate the strings from the body, so they used a neck through design, with hollow body wings, and a large brass inertia block under the bridge.

Another one would be the composite instruments, like the original Steinberger bass.

You can also stiffen wooden necks with carbon graphite bars, and use a lighter wood. Then you get a nice warm tone with great evenness and sustain.

[Ground Pounder]

Thanks for the reply David.

The concepts you're describing all relate to having the playing surface reside on a foundation. I'm thinking a little further beyond that.

Imagine the bridge, nut, and frets are suspended in place in mid-air. String up the bridge and nut (imaginary tension), and put a pickup in place below it - also suspended in mid-air. No foundation. Just the effects of the string vibration between the bridge and nut/fretted note, picked up by the pickup.

That's more like what I was thinking.

Crude theory one step further - say you place the bridge, nut, and each fret on it's own individual thick piece of rubber. Now put the strings on, and put a pickup underneath on it's own block of rubber.

Because all of the structural parts that are affected by the string vibration are isolated from allowing vibration to pass-thru (the rubber blocks act as each piece's individual shock absorber), you should be able to put this configuration on anything (given the same scale length) - an alder body with a maple/maple neck, a mahogeny body and maple-rosewood neck, a single piece of titanium shaped like a guitar, a granite counter-top... and because all of the componenet that are in direct contact with the strings are isolated, and the pickup is also isolated from anything except the resonance of the strings, it should in theory produce the same sound no matter what the foundation is.

That make more sense?

[Bruce Johnson]

There's one thing missing from your concept. You need to have some kind of a semi-rigid structural frame running between the anchor points of the strings (the tuners and the tailpiece). Otherwise, you can't pull the strings up to tension in order for them to make any sound. If you were to try to isolate the strings from that frame with rubber blocks, they would go "thud" and not make any identifiable ringing sound. That is, the movement of the rubber blocks would completely prevent the strings from making any sound other than the initial pluck.

If you're trying to get the pure sound of the strings and the pickup, that's easy. Just build the structure of the guitar as rigid as you can. The stiffer the structure is, the more you will be hearing the sound of the strings themselves, as detected and altered by the pickup. That was the whole point of multi-lam neck-thru guitars and carbon fiber that were the latest thing in the '80's. It was all about piercing high end and infinite sustain....and then you tried to use pickups, amps and synths to give it some "tone".

When you isolate the pure sound of the strings, what you get is a thin metallic "ding" similar to tapping a hammer on a steel rod. That's the sound that strings make on their own, and it isn't very appealing. You can play with pickups to boost or cut various parts of the frequency curve, you can add some distortion with a tube amp, or you can add flanging with an electronic box. But the core note is still a thin unappealing spike. You might as well be tapping a key on keyboard.

The whole point of the wooden frame of a good guitar is to add richness and warmth to the sound of the strings, in a way that can be modulated by the players' finger technique. It does this by minutely flexing as the strings vibrate, which adds subharmonics and background noise into the tone that's on the strings. The art of building beautiful sounding guitars is in balancing and tuning the parts of the structure, and matching it with the characteristics of the pickup.

Think about why the original all-composite Steinbergers dropped out of fashion so quickly. They were an amazing piece of engineering, very practical on the road, extremely consistent, and really boring to listen to. They sounded, literally, synthetic. They were pure strings and pickup, the ultimate electric guitar!