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Im working on a PRS semi hollow style guitar (mahogany back, carved maple top w/f holes) and was wondering if theres a difference with the sound and strength with hollowing with a big "U" chamber or using 2 separate chambers leaving a center block going through the length of the body?

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I'm not following the question... Can you get pics for us? I understand the "typical" tone block down the middle with two separate chambers, but I'm not following the "U" shape. So are you saying to nix the tone block completely? Like this?

Well my train of thought leads me to say that when you don't have a block of wood running down the center of the body, the instrument will respond and sound more like an acoustic, no? Because the more body wood you take away, the closer you get to simply being an acoustic.

Unless I'm misunderstanding the question completely. It's happened before.

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Well my train of thought leads me to say that when you don't have a block of wood running down the center of the body, the instrument will respond and sound more like an acoustic, no? Because the more body wood you take away, the closer you get to simply being an acoustic.

Unless I'm misunderstanding the question completely. It's happened before.

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I think he is talking about routing the center block away behind the bridge. You still effectively have the neck, pickups, and bridge all in solid wood. The difference would mainly be a larger common chamber as opposed to two seperate chambers.

Yeah thats what I meant, its just harder to explain without pictures. I decided to do the "U" route so I'll be sure to update on the tone and response once the build is complete

Thanks :D

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I like Howard Klepper's line on this (I'm paraphrasing)

'The chambers in my guitars are all tuned to specific frequencies. Of ocurse, I have no idea what they are'.

Brilliant :D , and even if he did know what they were tuned to today, when the humidity changes the woods charictoristics tomorrow it would change.

Peace,Rich

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General rule of thumb I've found: the bigger the chambers, the more 'acousticy' and lively the resulting guitar sounds. The smaller they are, the more solidbody-like things get.

It's not something I can quantify very well, but if I want something that's essentially got that solidbody tone but you want to reduce weight, smaller chambers will do the trick. I attribute it to the fact that the changes in resonance with multiple, smaller chambers are mostly due to weight reduction, while larger chambers more significantly affect the overall flexibility of the 'plates', changing the stiffness of the body, introducing more variation.

But like the others have said, it's not something I strive to control a whole lot. I just try to make sure the body's nice and resonant, however I've chambered it (or not).

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I have no clue why removing wood from the body would add anything to the sound of a solidbody electric. It does reduce the weight and make the instrument easier on your back. Possibly with an acoustic type Piezo and a standard wood and bone bridge like the Gibson LP version I have seen, this u cavity technique may have some effect on tone. But I fail to see how the removal of wood on a standard solidbody would be considered a tone enhancing procedure.

My personal view is adding f holes is purely an aesthetic touch. Removing too much wood would kill sustain especially along that neck and centerline of the body, and if you remove wood behind the bridge you will decrease sustain. Why else would people go to the expense and additional time to create neck through guitars, its to increase sustain. As long as you have built a sturdy guitar sound is related more to pickups and wood choices than anything else. Even in production instruments you will have variation in a given model due to the use of thousands of feet of lumber. Given computerized production techniques you will still get variations in sound on the same instrument, why its because of the wood.

Don't get me wrong I like the Idea of reducing body weight as long as your cavities are far enough away from the bridge. I use the technique to reduce weight myself. I have never thought of it as a tone enhancing technique

You take a great guitar like a PRS then add two cavities and a connection channel between the two and say it has improved sound, is it true? I would put it on my hype list. Besides don't these instruments use Piezo bridges too? Does anyone have the actual dimensions for this procedure, the connection channel may be a very small channel small enough to leave most of the wood on the body between the two channels intact?

I am not trying to persuade you to not try this, I just believe it will not make your guitar sound any better. I have seen many hype guitars go by the way side to believe all the claims I've read over the years. One of the reasons I tend to be conservative in my building decisions.

Anyway good luck with the idea hopefully you can find some solid info on the connection channel. Maybe you can fond a dealer willing to do a quick probe for you for a few dollars. With f holes it should be easy and take only minutes.

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A couple thoughts for you. First with a neck through guitar you contain the bridge, nut, and pickups in a solid stringer of wood. If you make that guitar smaller and have little material behind or on the sides of the neck, have you effectively killed your potential string through performance(as you see it)?

When you add wings to a string through section what effect does this have on the way the strings will vibrate? Now if you take the effect you get from added wings(if you believe the wings are going to change things in any way....) into consideration, and change the weight and the way wings resonate(with different volume or shape) will this change the way the string vibrate.

Sustain is proportionate to the amplitude of signal strength and duration. You can have a lower average amplitude that is present for a greater duration.

I had a long post, but I am going to drop it at that.

Peace,Rich

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It's not about 'adding' anything to the sound; it is about changing the character or nature of the sound. That's a straight-up fact, and is easy enough to verify for yourself by simply building a few guitars, and listening. Or even going to a store and playing a few guitars built in different styles. The Les Paul and the ES 335, f'r instance. Different woods, sure, but above all massively different construction. Necks, pickups, hardware are otherwise identical, but they don't sound the same at all. Take a Lucille vs. an ES, and you've basically got the same construction, with or without F-holes; one will feed back more, because the F holes loosen up the top, make it easier for the thing to vibrate.

The semis I've built with large chambers, blocked only under the bridge, feed back very easily. No f-holes, so it's actually very controllable (if you want it to feed back, it does, otherwise you can easily damp it). The ones with slightly smaller chambers feed back a lot less, and sound more like the solidbodies I've got. The guitars I'm describing are not identical, but they're all set neck, mahogany/maple bodies, mahogany necks, ebony boards, same scale length, all of them have humbuckers, and they're all roughly the same size and shape. What's more: the last three were made from consecutive pieces from the same board of wood.

Everything starts with string vibration. It's the source of your sound. The wood and construction choices filter said vibration (and how the guitar is built is one of the things that affects this), and the pickups then pick it up. Pickups make a huge difference. Then it's scale length, string choice, construction (set neck, bolt on, chambered or not), and wood. In my experience, roughly in that order.

In short, I don't disagree with you; I'm pretty conservative in my building decisions. Where you lost me was the word 'better'. It's just different, and it's a difference that's pretty darn easy to hear and note if you've built a few similar-but-slightly-different guitars.

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Look Rich you are probably correct and certainly have more builds under your belt than I do. I am certainly and old school builder at heart. However everything you said and wanted to say could possibly change if the top is flat rather than arched, the cavities are a different shape, no f holes, the top plate is a different wood species, the nut material is different, the bridge style is changed and a long list of other possible build decisions that may or may not effect the amplitude of signal strength and duration you refer to.

I think if you can recreate the same sound multiple times you have reached a level in your design, skill and wood choices and theories that few have mastered. So I agree with you but I can only generalize given all the choices one can make and the limited information provided by the poster. We all know that most people asking question here are on their first, second or maybe even have much more build experience than that, its always an unknow factor.

Again I was just adding my 2 1/2 cents worth of opinion here and dint intend to offend anyone.

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First, I am not going to claim I know more or am more experienced than you. I respect your conservative approach and am pretty conservative myself. Actually I have a lot of respect for you and that is probably the reason I wanted to chat a bit :D .

The main thing I wanted to convey, was regarding the effect of removing wood behind the bridge and potential effect on sustain. Effectively his modification does not break the continuity between the components that hold the strings and pickups. Really all that is being done is altering the material that is attached to the complete neck section. I can't predict accurately what changes will occur(that kinda follows what I said before in the topic), so I make no claims to such.

My comments on sustain were to through out a thought. I wanted to offer the idea that even if you alter a guitar in such a way that you decrease the amplitude of the fundemental. This may not decrease sustain, because a decrease in fundemental and possible strengthening of overtones may actually increase overall duration(sustain) of the signal. This creates a different sound (some say "complex") which may be good or bad depending on what you are looking for. It was just something I wanted to offer for your consideration, bouncing ideas off you if you will.

Peace,Rich

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I personally think that the 'U' shaped cavity will sound better than the twin cavity approach.

My reasoning:

Depending on how thin you leave the top and bottom (mine are all roughly 3 to 5mm depending on the type of wood) the sound will be altered more or less. If you think about trying to bend a thick piece of wood and a thin piece and comparing the degree of deflection, the thin piece will deflect more for any given force applied. The same would go for sound vibrations resonating the wood. A thinner piece will vibrate more and therefore be more resonant. With larger cavities, theres going to be more thin wood to resonate. In addition to this, when the U is introduced, the lengths of the thin sections of wood increase. Now think about how easy it is to bend a long piece of wood versus a short piece (of the same cross section)....the long piece is easier therefore on a guitar body the combination of larger and longer cavities are producing maximum resonance.

Now you could argue that the sustain will suffer dramatically by removing mass, but think about strumming a solid bodied electric guitar (with no amp) and an acoustic guitar. The acoustic will always beat the solidbody. The first few guitars I built were solid bodied, the next one had one side hollowed and since then the rest have had either both sides hollowed or the U shaped cavity. From my experience, the larger the cavity is, the better the guitar sounds and the more sustain it has. Since I tried using the U shape technique, I've never gone back to twin, single or solid. U shaped just adds so much character to the guitar's tone. To my ears, it just sounds better.

Pete

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How about an "O"-shaped route? :D

http://i134.photobucket.com/albums/q119/Ge...ct/100_5957.jpg

I just finished that guitar and it sounds amazing. The sustain is much better than another guitar I built that's solid with a bolt-on neck. Of course, to comment on what the chambering has "done" to the tone, I'd have to build this guitar again without the chamber. But it sounds beautiful.

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How about an "O"-shaped route? :D

http://i134.photobucket.com/albums/q119/Ge...ct/100_5957.jpg

I just finished that guitar and it sounds amazing. The sustain is much better than another guitar I built that's solid with a bolt-on neck. Of course, to comment on what the chambering has "done" to the tone, I'd have to build this guitar again without the chamber. But it sounds beautiful.

Heh, IIRC there was a guy on here who made a KILLER koa PRS hollowbody with the only wood connecting the top and back being where the bridge was and where the ferrules ran through the body. Simply beautiful.

And, of course, the circular tone chamber amplifies sound in much the same way that the LHC supercollider produces spectacular reactions from smashing together two proton beams. B)

Yeah, CERN builds guitars now, like Saab did to jet airplanes and automobiles :D

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It's not about 'adding' anything to the sound; it is about changing the character or nature of the sound. That's a straight-up fact, and is easy enough to verify for yourself by simply building a few guitars, and listening. Or even going to a store and playing a few guitars built in different styles. The Les Paul and the ES 335, f'r instance. Different woods, sure, but above all massively different construction. Necks, pickups, hardware are otherwise identical, but they don't sound the same at all. Take a Lucille vs. an ES, and you've basically got the same construction, with or without F-holes; one will feed back more, because the F holes loosen up the top, make it easier for the thing to vibrate.

The semis I've built with large chambers, blocked only under the bridge, feed back very easily. No f-holes, so it's actually very controllable (if you want it to feed back, it does, otherwise you can easily damp it). The ones with slightly smaller chambers feed back a lot less, and sound more like the solidbodies I've got. The guitars I'm describing are not identical, but they're all set neck, mahogany/maple bodies, mahogany necks, ebony boards, same scale length, all of them have humbuckers, and they're all roughly the same size and shape. What's more: the last three were made from consecutive pieces from the same board of wood.

Everything starts with string vibration. It's the source of your sound. The wood and construction choices filter said vibration (and how the guitar is built is one of the things that affects this), and the pickups then pick it up. Pickups make a huge difference. Then it's scale length, string choice, construction (set neck, bolt on, chambered or not), and wood. In my experience, roughly in that order.

In short, I don't disagree with you; I'm pretty conservative in my building decisions. Where you lost me was the word 'better'. It's just different, and it's a difference that's pretty darn easy to hear and note if you've built a few similar-but-slightly-different guitars.

For all the posts and threads I've ever read on chambering, (90% of the responses being nothing more than pure conjecture with no basis in fact)

This has got to be about the best response I've ever read. I need to save this and repost it for every chambering thread I read from now on.

Bravo Mattia! :D

Very Sorry if I be a naughty boy Setch. :D

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