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Semi-acoustic Vs. Chambered


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Think of it more as semi-hollowbody vs. chambered.

So a semi- is like a thin acoustic, but with a block of wood going down the middle? Is it like a thin, keck-through acoustic?

Not a neck-through, no. Although that could be possible.

I think a semi-hollowbody borrows from acoustic building techniques, but uses a central block for the neck, bridge and pickups, which prevents feedback and also allows the neck to be attached using standard setneck (or even bolt on) techniques. Semi-hollowbodies usually have arched tops and backs too, to allow for more air volume. But they're not meant to emulate an acoustic guitar sound. It's possible to build a full-hollowbody like this too, of course (I have an Epiphone Sorrento, which is a full hollowbody --it has separate blocks for the bridge and neck. The Danelectros used this kind of constructon too, by the way. Samick's Royale series uses a 'monoblock' ---essentially a hollowed out slab of wood, which is then covered with the top and back (and possibly sides, I don't remember). It's closer to a solidbody in sound, weighs more than a semi too.

A chambered guitar is another animal-- the chambering is usually meant primarily to reduce the weight of the guitar. The effect on the sound of the guitar is more minimal compared to a semi. Some guitars don't bother with the f-hole (like the Gretsch Duo Jet), some do, like the Tele Thinline.

I suppose one of the main differences between a semi and a chambered guitar would be air flow -- the air doesn't flow from chamber to chamber in a chambered guitar.

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The feedback you'ge all giving is extremely interesting. Based on the term "semi-acoustic", one could infer that the wood is braced like a traditional acoustic, and just as thin. From your descriptions, it sounds like a semi can (or is) made by hollowing out the body and putting a top on it.

If this is the case, are the back & sides routed fairly thin - maybe 1/4" or so - with a thin top as well? Would this thickness allow the wood to vibrate like an acoustic? Granted, the vibration would be significantly less due to the thickness of the wood. Also, if this is the case, how does the body handle the tension without cracking?

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The feedback you'ge all giving is extremely interesting. Based on the term "semi-acoustic", one could infer that the wood is braced like a traditional acoustic, and just as thin. From your descriptions, it sounds like a semi can (or is) made by hollowing out the body and putting a top on it.

If this is the case, are the back & sides routed fairly thin - maybe 1/4" or so - with a thin top as well? Would this thickness allow the wood to vibrate like an acoustic? Granted, the vibration would be significantly less due to the thickness of the wood. Also, if this is the case, how does the body handle the tension without cracking?

The terms are used kinda interchangably by many peopl, but I think people are basically giving you what most would consider the difference in the two styles.

As far as the functional difference between an acoustic(lets say archtop w/ pickup) and either of these styles of guitars. The center block is the main difference, which litimts the vibration of the vibrating plates(soundboard, back, plate). As far as how it can hold up structurally. Remember and acoustic flattop has larger strings and generally has to handle more tension than an electric. A flattop uses a soundboard in the .110"+/- .020" with light bracing to handle the full tension of the strings and tork of the bridge. You are structurally never even approaching anything that light with a Semi or Chambered guitar.

Peace,Rich

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From your descriptions, it sounds like a semi can (or is) made by hollowing out the body and putting a top on it.

No, that's a chambered guitar.

A semi is built more along the lines of an archtop (acoustic), except for that center block, which as fryovanni point out, prevents the top from vibrating like an acoustic. It's that center block that makes it a 'semi' after all. I don't know much about the construction of an archtop otherwise-- I know some are built using laminated wood.

I don't think it's a simple as carving out the wood as thin as possible and calling it a semi though. On the other hand, there's no reason why you can't build a guitar that way. Some of Rickenbacker's guitars are built in a similar way. I think Scott French's guitars are built that way too (I'm not sure how thin his backs get). I've built a couple like that too.

It's easier though to build a guitar like that in three layers -- a thicker center section and thinner top and back. And if you use contrasting woods, it looks great too.

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From your descriptions, it sounds like a semi can (or is) made by hollowing out the body and putting a top on it.

No, that's a chambered guitar.

It's easier though to build a guitar like that in three layers -- a thicker center section and thinner top and back. And if you use contrasting woods, it looks great too.

I was actually assuming there were f-holes in the top. My mistake for not specifying that.

What I'm considering is, when I finally get into the building of bodies next year, making a Les Paul but really hollowing out the body and adding f-holes. Maybe the body would be a little bigger, almost be like a mini-archtop.

What would be the effect if the wood was thicker than a standard semi-, like 1/4"-3/8", but without a center block? Would the feedback be overwhelming, or would it be there at all due to the lack of vibration in the wood?

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From your descriptions, it sounds like a semi can (or is) made by hollowing out the body and putting a top on it.

No, that's a chambered guitar.

It's easier though to build a guitar like that in three layers -- a thicker center section and thinner top and back. And if you use contrasting woods, it looks great too.

I was actually assuming there were f-holes in the top. My mistake for not specifying that.

What I'm considering is, when I finally get into the building of bodies next year, making a Les Paul but really hollowing out the body and adding f-holes. Maybe the body would be a little bigger, almost be like a mini-archtop.

What would be the effect if the wood was thicker than a standard semi-, like 1/4"-3/8", but without a center block? Would the feedback be overwhelming, or would it be there at all due to the lack of vibration in the wood?

I think your off on a tangent here with what would this or that be called (the question is fine, but I don't think it is going to help you much). What you are thinking about is using design elements from acoustic instruments to alter the sound of your future build. Go look into acoustic instrument designs and study up a bit on how they work, what they do functionally. Then after you have a feel for the instruments try to consider how you could integrate these elements to achive the sound you are after. I get the feeling most people who talk about semi's and chambered guitars never look to acoustic design to help understand what to possibly expect. I believe it would really help turn the lights on so to speak.

Peace,Rich

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Though I haven't delved too deeply into it, I have looked into how acoustics are made. I don't want to make one, which is why I wanted to know if semi's are make the same way. If they're not, then I might be able to do something with one next year. I haven't seen a concise answer yet, which is why I chose to describe my thoughts.

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Construction is mostly what its about, I feel; I won't called an ES chambered (Because it's not, it's a box with airspaces). Chambered guitars can be semi-acoustic, but aren't necessarily. It's largely about intent; how is it designed? Heavy on the acoustics, or mostly just an exercise in weight reduction?

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Though I haven't delved too deeply into it, I have looked into how acoustics are made. I don't want to make one, which is why I wanted to know if semi's are make the same way. If they're not, then I might be able to do something with one next year. I haven't seen a concise answer yet, which is why I chose to describe my thoughts.

Since your basing your decision on how acoustics are made(I am only assuming you are either talking about bracing a thin soundboard, or bending sides), then put those things out of your mind. First, you will not have to brace if you have a center block that the bridge is mounted in(you are totally safe structurally to use no more support). Second, Sides on acoustics(the rim) should be a very stiff element. If you choose to route all the way around the inside of a body, that forms a nice stiff rim (dandy!).

If you look into the design(as in what the elements need to do) in acoustics as opposed to the construction methods. Maybe that will free you up a little when your trying to catch the functional side of these things.

Don't forget to look into archtops also. You will find out that those F holes are not there only for air (some sort of helmoltz resonator type thing), as much as they perform a structural purpose that is critical in allowing the plate to vibrate well. Look at why they choose to arch (common on flatop acoustics also to have radiused or domed tops and backs). Look at the fuction of the recurve and how that area is adjusted to allow movement of the plate. You mentioned carving or arching, and F holes. Take a look at what the function is on an archtop with plates that produce the sound. Then you will be able to decide if using these will serve a similar function or if they are more or less eye candy.

Peace,Rich

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I haven't seen a concise answer yet, which is why I chose to describe my thoughts.

All right, I'll try one last time. Seems your real question is really about which build will be most feasible for you.

In that case:

A semi-hollowbody uses acoustic/archtop guitar construction techniques.

A chambered guitar is a hollowed out solidbody guitar with a cap on it.

I don't know how to be more concise than this. Since you're asking this question, I'm assuming you have little experience in building guitars. In which case, the obvious choice for you is to build a chambered guitar.

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Seems your real question is really about which build will be most feasible for you.

In that case:

A semi-hollowbody uses acoustic/archtop guitar construction techniques.

A chambered guitar is a hollowed out solidbody guitar with a cap on it.

I don't know how to be more concise than this. Since you're asking this question, I'm assuming you have little experience in building guitars. In which case, the obvious choice for you is to build a chambered guitar.

Thanks. That was EXACTLY what I was looking for. Maybe you said that the first time and I just didn't pick up on it. Thank you for spelling it out. What I don't want to do is bend the sides, work with thin wood, and essentially build a thin acoustic, therefore a true semi- is out of the question for me.

You are correct in that I've not yet delved into building. I'm planning on doing it next year, around tax time.

FWIW: I'm also going to get into doing inlay work. I'm not going to get into making necks, but I can certainly do some fancy inlay on them, as well as the body. I'm planning on doing inlay on wooden boxes for my family for Christmas next year. Those techniques will obviously carry over onto the guitar as well.

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Seems your real question is really about which build will be most feasible for you.

In that case:

A semi-hollowbody uses acoustic/archtop guitar construction techniques.

A chambered guitar is a hollowed out solidbody guitar with a cap on it.

I don't know how to be more concise than this. Since you're asking this question, I'm assuming you have little experience in building guitars. In which case, the obvious choice for you is to build a chambered guitar.

Thanks. That was EXACTLY what I was looking for. Maybe you said that the first time and I just didn't pick up on it. Thank you for spelling it out. What I don't want to do is bend the sides, work with thin wood, and essentially build a thin acoustic, therefore a true semi- is out of the question for me.

You are correct in that I've not yet delved into building. I'm planning on doing it next year, around tax time.

FWIW: I'm also going to get into doing inlay work. I'm not going to get into making necks, but I can certainly do some fancy inlay on them, as well as the body. I'm planning on doing inlay on wooden boxes for my family for Christmas next year. Those techniques will obviously carry over onto the guitar as well.

Take this for what it is worth. Honestly, removing all that wood form a solid body blank is not easier, I actually find it harder (I think Mick and I have different opinions on this, but I think he is telling you what you want to here). If you are more comfortable with a router than bending sides (this seems to be a bit of a mystery to people who have never done it, but ask anyone who has bent and they will tell you it is NOT difficult) then you should use a router. You should use what ever methods you prefer, and have fun with the process (that is what this is all about). You CAN do anything you want to do, No worries, and enjoy the process :D

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Take this for what it is worth. Honestly, removing all that wood form a solid body blank is not easier, I actually find it harder (I think Mick and I have different opinions on this

Not really. It's exhausting work and not really the most enjoyable part of building. I've since gone back to building plain ol' solidbodies.

On the other hand, my guitar teacher has rigged up a nice side-bending device that he's going to let me borrow when I'm ready to go acoustic...

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Rich: chambering is easier purely because you don't need to make a bunch of jigs or tools (either a bender, or a mold, and if you want something with sharp bends like an ES-335, that ain't simple). If you have a router and a drill press, you can chamber. Makes a big mess, sure, but it's not terribly difficult or anything...

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Rich: chambering is easier purely because you don't need to make a bunch of jigs or tools (either a bender, or a mold, and if you want something with sharp bends like an ES-335, that ain't simple). If you have a router and a drill press, you can chamber. Makes a big mess, sure, but it's not terribly difficult or anything...

Mattia: I agree you have to buy tools, and make jigs. I don't find bending the sharper radius to be extreamly difficult (maybe I am just lucky and have never had an issue?). Hogging out a body with Forstner bits is time consuming and messy, then you either have to route (or sand, ugh...) the area smooth. To me all that removal of material is really more time consuming and messy. If given a choice of methods, I would bend. That is just me. As I said I recommend he use whatever method is most comfortable, but I don't want anyone to get the idea bending is difficult(yes, I am trying to sell the idea to anyone reading, because I strongly believe anyone can pick up on bending, and it is a great skill for someone who builds stringed instruments).

I don't want people to avoid it because there is a percieved high degree of difficulty. I think it has many advantages if of course it fits the design. Less wood is used for sure, one solid body blank is about four bd. ft. , the same amount of Mahogany would yeild at least 4 bent sets with full length center blocks (if you were using heel and neck blocks you could make many more sets). If the bending was risky or you needed practice, you could slice up 3 center blocks and 6 sets of sides with the same amount of wood. If I bought about 1.25 board ft. of mahogany(2.5" x 36" x 2") and resawed it for sides, I would have at least 5-6 sets, that is about $2 per set, if I paid a full $10 bd. ft. for the Mahogany. Even if you just use a basic pipe setup and it takes a few sticks to get a feel for the tool. You are not out much, but what a great skill to add to your box of tricks :D

Peace,Rich

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The two different building methods being described here produce two very different instruments. They feel and sound different. The decision to build one or the other should really be based on what type of instrument you want, rather than what sort of building method you want to avoid. If you want a guitar like a es335, and you chose to hog out a solid body blank, you may end up with a great guitar, but maybe not quite what you were hoping for. But if you want something more like a tele thinline, that would be the way to go.

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On that note, let's take this in a slightly different direction.

Let's say you hollow out a body like this one here. Maybe you even take out the two lines between the bridge & the very bottom, creating a huge chamber inside, f-holes and all.

1) Would this become a feedback monster?

2) How accurate an acoustic sound do you think piezo pickups would deliver?

3) Would that big of a chamber radically effect the overall tone as opposed to smaller chambers, like a thinline?

4) What if there was no center block, and the entire thing was hollow? The pickups are mounted directly into the wood, and it's all 1/4" to 3/8" thick. Does that really monkey thing up?

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