What's the difference between hollow body and hollowed out?

[Mark Hammer]

I'm talking about the physics/mechanics of their respective sound. By "hollow body", I mean those instruments that have a back, a top, and sides, comprised of separate pieces, with or without a center-block. By "hollowed out" I mean those instruments like the Gibson Midtown and similar, where there is no "back" and "sides", but rather a single block that has been hollowed/routed out to form a big resonant cavity, and then has a top affixed to it, with F-holes. This latter form-factor is not intended to be the same as a "chambered" instrument, with body-hollowing to reduce weight and add some resonance, but rather meant to be a different sort of semi-acoustic.

So, what happens, or perhaps doesn't happen, when the back and sides are one big continuous hunk of wood?
How much of that is largely because of the kind of wood used for it, as opposed to the structural qualities? (My sense is that maple is often used for hollow-body, but mahogany for hollowed-out)
Do folks have any good or bad experiences with hollowed-out models, or caveats they might mention?
Are there significant design aspects that have to be omitted, or added, with hollowed-out? (e.g., I gather highly arched backs are unlikely)

[bbsailor]

I'm talking about the physics/mechanics of their respective sound. By "hollow body", I mean those instruments that have a back, a top, and sides, comprised of separate pieces, with or without a center-block. By "hollowed out" I mean those instruments like the Gibson Midtown and similar, where there is no "back" and "sides", but rather a single block that has been hollowed/routed out to form a big resonant cavity, and then has a top affixed to it, with F-holes. This latter form-factor is not intended to be the same as a "chambered" instrument, with body-hollowing to reduce weight and add some resonance, but rather meant to be a different sort of semi-acoustic.

So, what happens, or perhaps doesn't happen, when the back and sides are one big continuous hunk of wood?
How much of that is largely because of the kind of wood used for it, as opposed to the structural qualities? (My sense is that maple is often used for hollow-body, but mahogany for hollowed-out)
Do folks have any good or bad experiences with hollowed-out models, or caveats they might mention?
Are there significant design aspects that have to be omitted, or added, with hollowed-out? (e.g., I gather highly arched backs are unlikely)

Mark,

Consider the design of the guitar as it relates to how much energy the body style sucks from the strings. In the very early days of guitars playing in big bands, the non-amplified guitarist sat in the rhythm section and only the initial attack strum was heard to supplement the rhythm or accent fill ins. In those days having a good acoustic projection was necessary, thus having big bodies with carved tops and backs. When electric amped guitars were introduced initially the big bodies were used with very early pickup designs. Later, body styles changed as the body was no longer required for good projection; just turn up the volume on the amp.

Body styles with pickups have a far greater range of flexability in their design. Styles include (1) expensive carved tops and backs, (2) pressed laminated tops and backs, (3) solid bodies, (4) hollowed out solid bodies to reduce weight, and (5) center solid cores to have a hybrid sound between electric and acoustic bodies and reduce potential feedback. Each of these body types changes the amount of energy being sucked from the strings and ultimately the amount of sustain left for the string to ring and ultimately the playing style that a particular body style supports.

I hope this helps.

Joseph J. Rogowski

[Mark Hammer]

Not yet, but I appreciate the effort. My question is really regarding what the difference is between these two instruments. The upper one is an ES-339. It has the usual maple back, sides and top, with a center block. The lower one has a maple top, but the "sides" and "back" are one big hunk of mahogany hollowed out to mimic having sides, a back, and center block. It is a bit thinner, top to back, but beyond that and the wood used, what are the differences in the physics of the instrument? For instance, does the presence/absence of kerfing make a difference? Does all that glue make a difference? Does the "continuity" of the wood that forms the back/sides in the Midtown damp/undamp things that the joining of back and sides doesn't?

Or is it all about weight and cosmetics?

[bbsailor]

Mark,

Sorry I failed to answer your question but I found something that should get you closer to what you want.

See this web link: http://www.barbarossa-guitars.com/mi...cle/Struct.htm "The Guitar As A Structure".

Decompose each of your guitar types as far as differences in:
1. Construction methods
2. Wood type used in various guitar parts; see link on top of first page "wood choices" and
3. Other guitar characteristics covered in the article.

This should give you a good feel if the differences are cosmetic, balance, weight related, structural, or simply the economy of construction. As these guitars are electric, their acoustic qualities should have minimal influences. It really gets down to the neck, fingerboard, fret leveling quality, neck setup, string setup, bridge setup, pickup setup and the overall feel of each guitar for the style of music played.

Not sure if this will help, but give it a read.

Joseph J. Rogowski

[Mark Hammer]

I'm going to have to print it out to be able to give it a proper read, but at first blush it looks terrific. It may not tell me exactly what I wanted to know, but the ride looks like it will be fun.

Forgot to say a big thanks for that, Joe. Much appreciated.

[Steve A.]

I haven't read that link yet but I think that if the sides and back are made like an acoustic guitar then there is going to be plenty of elasticity in the air inside which will contribute to the sound. I have a few guitars that are made from a solid block of mahogany which is carved out (except for the center block peninsula) and I don't consider them to be true hollow or semi hollow bodies.
I play my guitars without an amp as much as I play them with an amp and I hear and feel a big difference between the two methods of construction.

Just my 3.58 cents worth (price adjusted for inflation)

Steve Ahola

P.S. Speaking of construction methods the current generation of cheap imported guitars with "bound necks" are not bound in the traditional sense with binding glued into a routed channel in the neck. They use a 3 sided plastic box that sits on the neck with the fretboard set inside of it. One problem with that design is that the sides of the plastic box are much thicker than binding so the fret tangs need to be trimmed back more. (If the frets are glued in then that is less of a problem.)

[Mark Hammer]

Anybody ever tried any of those Jon Kammerer guitars? They're another version of the "hollowed-out" form factor. Home

[Steve A.]

Since posting here I decided to check out my old Epiphone Alley Kat from the mid-00s with the back and sides hollowed out from a single of wood. There is no center block running under the pickup cavities, just a block in the middle under the bridge.

Damn- that guitar sounds better acoustically than my Heritage H535.

Steve Ahola