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Sustain-o-matic Guitar Chair 3000: The Ultimate Resonance Experience

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Hopefully my title interested a few people. :D

I'm a senior in high school, and in one of my classes I have a yearlong project where I identify a problem and solve it, or just make improvements to something. With that in mind, I figured I'd do something guitar-related, particularly with resonance, tone, and sustain in electric guitars (and maybe acoustics if I have time).

If I'm not mistaken, resonance is the guitar vibrating as you play it, tone is the "personality" of the guitar, and sustain is how long the notes ring out.

I want to separate "plugged in" sustain (like effects pedals, sustainiacs, putting the guitar right in front of the speaker to reflect vibrations, etc...) from natural sustain, which is not necessarily unplugged, which could just be plugged in with no extra effects straight into an amp with no effects or add-ons. For this project, since I lack a lot of electrical knowledge (for now), I wanted to focus on organic sustain, resonance, and tone.

I'd like to come up with a design to increase organic sustain (which I will just call sustain from now on), but also resonance and tone. I understand increasing tone sounds a little squirrelly; I'll have to come up with a more specific description. I have read in a few places on the internet that the more resonance you have, the less sustain you'll have because resonance is the body absorbing the strings' vibrations, thus shortening their time of vibration. Any thoughts on that idea?

It's pretty common belief among many guitarists that more wood = more sustain and tone, though I'm not really sure if that's true. Wouldn't more wood increase the resonance and thus decrease the sustain? I understand that quality of woods and joints are very important to sustain and resonance, maybe even more than anything else according to a lot of luthiers.

So right now my basic idea is to make a chair that is made of solid wood. That chair can be connected to a matching solid body electric guitar in such a way to increase resonance, tone, and sustain (hopefully). Of course I'd pick woods and hardware that would give good sustain and all that. I'd probably use bolts and shape the guitar in a certain way so that would work ergonomically and still be solid. Of course that'll take away the ability to position it however, but who knows. It's basically just a really big body that you can sit in. I think the experience would be very cool: a nice big chair that surrounded you with the resonance of your guitar. I had a similar idea for an acoustic, with some hollow sections that would project sound all around you from the guitar.

Of course this is all a pretty complex plan that I'll need to think about and draw up a bunch, but right now I'm just testing the waters, seeing what some of the most experienced people with guitars think about my idea. And I will post lots of pictures if I go through with it. :D

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Some interesting 'off the wall ideas' but I think you perhaps need to look into the science of all this a fair bit and make some 'definitions' more closely...

In particular you need to think about "reinforcement" and "damping" of vibrations...

The waves in a guitar note are complex, you can reinforce some harmonics and dampen others, this will give some of the tonal character in a guitar for instance, what is 'preferable' tone...well, that's more subjective...there is no such thing as "more tone" if that makes sense...

Something that reinforces a band of frequencies may create "more sustain" but that same thing could be dampening the sustain of another frequecy...

I don't think there really is a "more wood" theory...basically, if something is stiffer then there is going to be less interaction between the strings and the instrument and this might give you more sustain, but then affect tone or other aspects...some designs can reinforce certain frequencies and so appear to sustain longer...

Remember also that there are some physical laws, beware trying to make a perpetual motion machine. Without the infusion some energy, say in an amplifier, you can only get so much out of a system.

Anyway, a huge area of study there...not sure that your application has any merit, but studying the science will let you into what is at work...

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Resonance and sustain can and often do coexist. Resonance is the sympathetic vibration of a structure due to the vibration of another structure. The reason that some people think that resonance and sustain are trade-offs is because of the most common mode of inducing the sympathetic vibrations. If you are coupling the two structures (string and guitar) purely by mechanical means, then yes, you will typically have less sustain because the guitar will be acting as an energy sink for the string. However, if you can create a sufficiently rigid boundary condition on your string (more mass, like a really heavy bridge or more wood, etc.), then the string will tend to ring out longer. So if you can use the air to induce the sympathetic vibrations in the wood and not the mechanical coupling, you can have resonance and sustain at the same time. Keep in mind, though, that air is not as efficient at conducting the string's energy to the guitar as a mechanical connection (the bridge, nut, etc.), so there is still some trading off to be done.

Tone is a whole different ball of wax. That is where materials come in to play much more. Where sustain is almost purely about mass and rigidity and resonance is a half way point between mass and material qualities, tone is more exclusively about material qualities. This means that two materials of the same rigidity/density, etc. can have much different tonal qualities even though they may produce the same amount of sustain. Also, tone is very subjective and what you may think is perfect, I may think is hideous and vice versa.

As for improving this in a guitar, you are going to be trying to improve a design that has been hundreds of years in the making in a single year from a relatively lay person's perspective. I am not saying it can't be done, advancements are made all the time. Just be aware that there are going to be trade offs and be aware of what they are. As for the chair idea, remember that the mass of the person sitting in it is going to alter the complex vibration of the structure, so each different person will experience a different effect. This may be a fun thing to illustrate, but just be aware that it will happen. I honestly don't think adding a guitar to a chair is going to make a radical change, but as we like to say in physics, you never know until you try. In other words "I wanted to see what happened" is the basis of all good science. :D

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Pretty much all of the above ;-) From the other end of the field you have:

A notes sustain is directly related to the system losing energy from conversion and losses.

- vibrating string (and to a lesser extent, body) interacting with the air and other "connected" mediums loses energy from the system

- vibrating physical parts heat up (which is how sound insulation works also)

You can see where I'm going on this one anyway. It's losing battle unless you can feed more energy into the system, so all you can do is mitigate losses. Identifying the sources is the first step.

I say, play a hot guitar in a vacuum.

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Resonance and sustain are aligned, not opposed, I think. The material that the strings are tied to will absorb their energy. When the resonant frequency of the tied-to is related to the frequency the strings are producing, you will have more resonance (because the material is excited to its natural frequency by the string) and more sustain (because the material is working in harmony with the string and taking less energy out of it).

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