Hollow Body Depth and Influence on Tone

[capt_kurk]

I wonder what the depth of the body has to do with the overall sound in an archtop, both electrified and acoustically.

I know on most flattops, a deeper body often means more of a mellowed, darker tone and a little more volume, depending. But does that still apply to an archtop?

[Squint]

The 3" 1988 MIJ Wasburn J6 in the center of this photo used to be my main "jazzer", but it was so freakin heavy, it really got to be a literal pain in the neck.

Then, the much thinner and lighter Washburn J9 MIJ prototype (yes, a REAL prototype verified by Washburn through the s/n) above and to the left quickly became my favorite for jazz and I sold the J6. The J9 actually has a deeper and "woodier" tone than the old J6 and is by far, after a PLEK set up, the smoothest jazz guitar I have personally ever owned.

The Washburn Korean J9 to the right I call my "White Falcon Killer". She's got two GFS Dream 90's and a top line Bigsby that takes care of any rockabilly or country tunes I come across.

And of course, the two MIJ D'Aquisto Centuras on the flanks, one w/ flatwounds for jazz and the other w/ roundwounds for everything else, fill in the empty spaces rather nicely. The Centuras really shine in the studio with the right mic placements.

[Groyniad]

I'm all about this topic at the moment. I am having to sell my adored Comins archtop because I can't live with the 3 3/8'' depth. This is the traditional spec - 17 x 3 and a bit'' (es 175 has same depth but 16'' bout).

I don't play these things a bit, a play a lot, both alone and in public. So comfort is about, oh, three times more important than you might initially suppose. If you practice a lot and play a lot you have to be comfortable with your instrument. That involves working really hard on posture in playing (what a pain in the damn backside) more than it involves changing your guitar - but you probably need to do both. Body depth - along with lower bout width - is a fundamental ergonomic consideration.

I used a thinline archtop for a short time recently - a very good one, made by the very amazing and wonderful Mr Mark Campellone. If I wanted to equip myself with a range of good guitars I'd never let it go, but I'm a one guitar at a time kind of guy (I only play one 'style'.) Because this particular instrument was made by such a guitar-dude with such incredible materials (it was made with all European tone woods) it has incredible acoustic responsiveness. Its not that LOUD acoustically but its full and INCREDIBLY precise. Its way more precise tonally than the best 16 x 3 instrument I've ever played. That's largely because there's a bit less going on 'in' the note it produces - and the note comes out at you a bit quicker. The notes are neater - and the acoustic sound is sort of tidier (and a bit quieter) than an equivalent quality 16 x 3. If you are into precision this sort of instrument (well made) can deliver.

It is also much much more comfortable to sit or stand with. (much)

And a little more resistant to feedback.

As you increase the depth (all else being equal) you increase the bass response. The bass response is largely what is responsible for feedback - but its also contributes powerfully to the sense of depth or richness in the tone. And the wider the guitar the less comfortable it is to play. I do not know how serious acoustic guitar players survive.

[Patrick2]

I would agree with pretty much all of what Groyniad said. But, I would also add the following; Groyniad is giving you a description of his own comfort . . or discomfort level with the size of a guitar. Yours will obviously be specific to you. An 18" Super 400 has a 3-1/2" body depth and can be a real difficult guitar to play for a long period of time . . . if your physical stature is that of a smaller person and you prefer to play standing up. However, to a gentle giant like Kenny Burrell (6'-4" ish). . . it's been his go to guitar for the past few decades. I'm sure he plays quite a bit. So, as far as comfort goes . . it's best to experience that for yourself.

As to relates to tone, I totally agree with everything Groyniad said. I would just add the adjective "big" to what he says about the voice of a deeper box. To me, a big voice means much more than loudness, more bass or bottom end and'or boomier. I have several 18" arch tops. Most are 3" depth, one is 3-1/4" and one is 3-1/2". My L5 guitars are 17" X 3-3/8" I play mostly sitting down with the guitar held in a classical guitar position. I am 5'11" and find no discomfort what so ever. However, based upon Groyniad's comments of how much he plays . . . he probably spends more time warming up than I do playing. Also, I play acoustic, unplugged far more often that I do amplified. So, for me acoustic tone is quite important in my guitars. Even more so than when I am listening to another player.

With all else being equal, the deeper box will give you a far "bigger" voice than a shallower one will. The deeper box, in my opinion, enhances each of the individual acoustic tonal properties of a guitar.

Although the deeper box is definitely my own preference, I can't really say the it will give you a better voice than a shallower one . . . because there are wonderful complexities to each.

[Squint]

Patrick is spot on, though. Especially playing acoustic vs. amplfied. So many different things factor in... the size of the lower bout, the woods used, the liveliness of the back as well as the top...

That's why we keep getting GAS... the neverending search for our next favorite guitar!

[capt_kurk]

I think I can relate to you in comfort Patrick. I tend to play in a classical position, even with my tele, so to me, unless it's more than 3.5" deep, I don't really mind (I'm also 6' tall, so yea...) Similar deal goes when I'm standing.
I'm kind of hoping to find an archtop with some "oomf" in its sound, not necessarily loud and poignant...I want it to feel to me like a noticeable sound that's still warm and round.
I suppose a good way to visualize what I'm trying to compare is the Godin 5th Ave (electrified or not...) at ~3", the Eastman AR371CE (3 9/32") or AR503CE (2 9/16"), and an Epiphone Broadway Elitist (3 3/8").

[Jabberwocky]

Phillip Stauber does not look like a very large man but he handles his Super 400 CES with some ease, it seems :

.

[Groyniad]

Whether you end up with nasty aches and pains is a lottery. What can happen I think is that you start to feel uncomfortable - ignore it - and then really mess yourself up.

Patrick - the super 400 looks totally natural 'on' Kenny. I'm 5 10'' - I'm sure it looked a bit silly on me. If it looks comfortable it probably is. I think some players might not want to sacrifice speed of response for bigness/depth of tone - that they may want a smaller body because the note doesn't rattle around in there for too long before it comes out and says hello. (So that is, even if they're comfortable with it and they can deal with the feedback issues).

This depth/bigness/richness-of-tone thing is right at the heart of the music - or that over-folding of music and instrument that is deeper than the (obvious) contrast between them (man).

I just saw a certain Larry Carlton (who I didn't know from Adam until half an hour ago) playing with the very great Tal Farlow (you tube can hurt your head sometimes). The extraordinary contrast between their ways of playing that tune (Misty) is at least a great deal to do with sound. Larry has the thinnest body guitar you can have - it ain't got no rims man (or its all rim, one or the other.) Tal has a classic gibson jazz box.

Its amazing. You take an L5 ces - say - and you gradually make it thinner 'till there ain't no air between top and back - and as you do that you cover the distance between powerfully distinct cultural worlds - between jazz and rock - between the forties and the seventies. Just by making a guitar thinner!

I aim to make my guitar as small as I can (reducing feedback pain and back pain) without losing too much bottom end in the sound (I want that bottom end in the melody notes just as much as in the bass notes). That 'thick' sound is what drew me to the guitar - to jazz guitar - in the first place.

There's a big difference between e.g. 14 x 2.5 (only one of Benson's Ibanez guitars comes to mind here) and 17 x 2 3/16 (L5 CT/Byrdland territory). Surprisingly perhaps the 14'' guitar retains the sound of the full size (which I take to be 16 x 3) slightly better than the 17'' thinline version of the instrument. I don't know which inhibits feedback more effectively.

[Groyniad]

One solution is the Kevin Ryan armrest bevel idea. I have a flat top built by Matt Mustapick that has this feature and it is the bee's knees for comfort. It can be applied to archtops. Here's an example from Ryan Thorell. You get both the depth and the comfort.

Damn - depth of tone and comfort - like having caking AND eating it too. Shouldn't be allowed.

[oldane]

As you increase the depth (all else being equal) you increase the bass response. The bass response is largely what is responsible for feedback - but its also contributes powerfully to the sense of depth or richness in the tone. And the wider the guitar the less comfortable it is to play. I do not know how serious acoustic guitar players survive.

I agree to this about the sound. When I ordered my Triggs Master 400 (a 19" Stromberg copy), I discussed the body depth with Jim Triggs. He would prefer to make the guitar 3" deep but found it OK to go up to 3 1/4" - but not more than that. With greater depth, the bass would become too dominant and the overall sound too mushy, meaning less projection. And projection is what a guitar built for acoustic 4-to-the-bar stumming is all about. It's also important to realize that what the guitarist himself hears is not the same as the audience, even those sitting just a few meters away, will hear. So if one plays for an audience, one has to take that into account.

With archtops amplified with a magnetic pickup, the body depth becomes less important for the (amplified) sound, so here ergonomy considerations can have higher priority. The Painter guitar, I had made last year, is 2½" deep, and it is significantly more comfortable to play than full depth instruments without anything missing from the amplified tone. Due to the reduced depth and the fact that it's a plywood guitar it's certainly not much of an acoustic guitar. It will do for practice at home in a pinch, but not more than that.

As for the width of the guitar, I don't buy the idea of "the smaller the more comfortable". That may be true if you play standing with the guitar on a strap, but if you are sitting and not using a strap, too small a guitar can mean a too low position of the guitar so the left and/or the right hand have to reach for the strings. For my body size, a 17" inch guitar is the most comfortable when sitting (and 17" is what my Painter is). I also have an old Gibson 175, and I have never felt really comfortable with it when sitting, have always had it on a strap. The waist is too narrow, so the neck is too low, and the position of the neck when sitting is too far to the right. Now, that is not a fault of the 175, but rather of my particular body shape (long torso, short legs and arms). Most people love the 175 for its smaller size.

How do I survive with my 19" wide and 3 1/4" deep Triggs? Well, first, it's the lower bout which is that wide. The upper bout and the waist has the same dimentions as a normal 17" archtop. Second, I play it in the Freddie Green way - left thigh crossed over right thigh, the guitar lying on my left thigh in a flat position (30 degrees from all flat). That position actually helps getting a more comfortable strumming position for the right hand and I don't feel the size of the guitar at all. If you check old photos of big bands, you'll notice that many (the majority?) of the rhythm guitarists held their guitars that way. Allan Reuss with Benny Goodman is an example.

[Groyniad]

Fascinating to hear your views on these matters. Really interesting about guitar ergonomics. I've just had to put the most amazing full size archtop up for sale because I can't sit comfortably with it. I find the 16'' more comfortable in my lap. I'm trying to work out - after a very long time playing - how I should sit. I've never even tried the position you describe so clearly. Last night - for the first time ever - I discovered that I could sit - with a strap - in a sort of classical position - and it felt really great. In particular it felt like I could sit with a straight back very upright looking straight ahead - rather than bent over the neck a bit. It feels to formal to me this position - but it also feels more comfortable.

Very interesting to hear what you have to say about small lower bout sizes. I am just now experimenting with a 14'' archtop. Its 2.5'' deep. Too soon to say how it will turn out comfort-wise.

[Jabberwocky]

I agree with oldane. I'm a small guy (5'8"). I got myself a drummer's throne (Roc-N-Soc) and a Tempur lumbar/lower back support contoured memory foam cushion (12"x10"). I place the cushion over my right thigh and rest the waist of the archtop over it. The upper bout of the archtop isn't all that big (even that of a Super 400CES). Yes, the lower bout dangles off to my side. I find it manageable. My playing position is very much like Phillip Stauber's as seen in the video. My right elbow drapes over slightly behind the waist of the archtop, not over the lower bout. (I borrowed a Super 400CES; I am getting my own this fall...or at least, I hope to.)

The memory foam lumbar support cushion really helps to make the archtop comfortable.

[oldane]

As for sitting with a guitar, for my recent 60th birthday my wife gave me a chair designed by the famous Danish furniture designer Hans J. Wegner. When John F. Kenndy and Richard Nixon had their final TV duel in the predidential election 1959, they sat in two of Wegners chairs. Wegner was a furniture maker (do you call it cabinet maker in English?) before becoming a furniture architect, and his personal experience with woodworking is seen in his designs, which is always very well thought out and very functional - and usually also with excellent sitting comfort. The chairs are now made by PP Furniture in Denmak, and the workmanship is excellent.

My chair is a little less known model called "Jakken hvile" (= "the jackets rest"). I really find it being witty, functional and very comfortable for an upright sitting position. There's great support for the whole back including the lumbar part. It's originally envisioned as a chair for bedrooms, hotel rooms etc. The built in "coat hanger" for a jacket is obvious, but the seat is hinged at the front, and when flipped up, the trousers of the suit can be hung nicely on the upright seat. Underneath the seat is a small compartment for placing keys, a wallet etc. for the night.

Apart from being very functional, IMHO it's also beautiful and is a scupture in the room.

I have wanted that chair for years, but it's not that cheap and it has to be custom ordered, so I have shyed away from getting one. But now, my wife gave me one. It's the best gift I could have.

Due to the great back support, it's works excellent as a "guitar players chair".

You can see it here (not my sample):

Google Image Result for http://www.fanantique.com/Images/400/DD0081_1_400.jpg

[Marty Grass]

How does the depth of the body affect volume and clarity with and without amplification?

Does it make much difference whether the depth is 3 3/8" vs. 3" as far as sound goes?

I had an early Howard Roberts with carved woods. That was 3 3/8" deep and 16" wide. There seemed to be a built in "delay", sort of an echo. It was gone of course when amplified.

I find the 3" bodies a bit more comfortable, but no big deal either way.

Thanks.

[Archie]

The thinner the body, the thinner the sound. Not to say brighter (although that happens too) but just not as deep, literally lol

However a good luthier can make bodies like the Johnny Smith sound like a full boded L5. Depends on the woods, carving, brace type and experience

So to summarise, it makes no difference but should all things being equal (which they're not in guitars and why it therefore makes no different), you should be able hear the deeper or thinner tone.

[Marty Grass]

I think the "fatness" of the sound from a deeper body comes from the vibrations bouncing between the top and back slightly out of phase. That should cause a temporal expansion of the note, slightly different from just sustain in that it is more of a quickly repeated echo.

[coolvinny]

I don't think it affects amplified tone, but unamplified yes it will make a noticeable difference.

I have a 3.75" deep 15" archtop and the depth lends itself to more volume and especially bass.

The most noticeable difference would be in comfort though...especially if one plays while standing rather than sitting. Every 1/8" is noticeable I find. Even with my main virtually identical 16" archtops...one has more arch in the back (the carved guitar) and the other is flatter (the laminate) and although both are 3" deep at the rim, the laminate is more comfortable standing.

[pingu]

ok i'll bite ...

I believe the internal volume in Litres
of the guitar is important in controlling
the bass response of the guitar
hence the 'warmth' of the instrument

likewise the speaker enclosure

the bigger the volume in litres
the lower is the resonant fz

so Gibson made the 175 pretty fat
to get good bass response I reckon

[Archie]

Actually thats really interesting. I was about to reply that i thought the ES-175 was too deep, as the bass (imo) sounds mushy. I then read in another thread that Jim Triggs claims that if a guitar is too deep, the bass becomes mushy.

Seems my thoughts were right all along, the Es-175 is too deep. Thats why I've always liked my Japanese stuff. They make Es-175 models but with half an inch to an inch less in depth. You still get the same warm laminate tone but you get so much better bass response.

[Greentone]

Marty

My experience has been that the shallower (3" to 3-1/4") 16" body carved archtops are capable of providing a natural reverberation to the acoustic sound that other archtops just don't have. This is especially prominent in the original series L5 guitars. Every early L5 (16") guitar I have played had an audible reverb--perhaps what you identify as echo--especially around mid-neck, and prominent on the first three strings. This is also noticeable on the early, black L10, L7, and mid-30s L50 (all 16" guitars). I have noticed it on some 30s Epiphones, too, but especially on Gibsons.

The 3" depth Gibson Johnny Smith guitar didn't have this reverb, but it is one of the best sounding guitars in other regards that I have enjoyed. That shallower depth has something going for it.

I think that the folks at Heritage picked up on this when they built the forms for the 16", 17", and 18" guitars. The fully acoustic Heritage archtops that I have played (my SE has two set pickups) sound really nice with the shallow body depth.

The big body, 3-1/2" depth carved guitars produce a soulful, deep response that is pleasing, too--but in a different way. There is no denying that an acoustic Super 400, or a D'Angelico New Yorker is a spectacular sounding guitar.

For a tour of the different acoustic archtop tones, everyone should listen to David Grisman and Martin Taylor's "Tone Poems" album. Taylor plays a different archtop on each chart on the album, with a complete description of the instrument's history. You can readily discern the difference between the 16", 17" and 18" (and larger) instruments.

[kenbennett]

The air tone, the Hemholtz frequency, is determined by the ratio of the volume of air inside the guitar body to the area of the sound holes. Therefore adding 3/8" to a 3" body adds about 12% to the air volume, if the total area of the sound holes was also increased by 12% then the effect on the tone would not be noticeable. If the sound holes were kept the same size and only the air volume was increased, then the tone guitar would have a lower resonant frequency which would definitely affect the tone. Whether it's better or worse depends on a lot of other factors.

[bananafist]

Interesting info KB. Does that work in reverse, reducing the area of the sound holes in a given body depth could/would increase the bass end response? Or am I misunderstanding?

[kenbennett]

That's basically correct, but it's just one factor contributing to the total tone profile. Nobody completely understands why acoustic instruments sound the way they do in all details.

Here's a quote from another builder Martin Keith (The Auriole is one of his flattop models):

"For any acoustic enclosure, the area of the soundhole is vitally important to the tuning - in fact, it is the single most important variable, and small changes can make a big difference. The Auriole soundhole is carefully sized to maximize the bass response of the guitar without compromising treble clarity."

Somebody has made an archtop with adjustable soundholes. I think D'Aquisto did it. You can slide a thing to cover part of the hole. I always wanted to try that.

[TH]

The air tone, the Hemholtz frequency, is determined by the ratio of the volume of air inside the guitar body to the area of the sound holes. Therefore adding 3/8" to a 3" body adds about 12% to the air volume, if the total area of the sound holes was also increased by 12% then the effect on the tone would not be noticeable. If the sound holes were kept the same size and only the air volume was increased, then the tone guitar would have a lower resonant frequency which would definitely affect the tone. Whether it's better or worse depends on a lot of other factors.

Exactly. I've been working with plate tuning and resonance balance between top and back wood resonances and air modes, and Ken you've got it there. I will say that a while ago I built a really shallow 17" maple spruce X brace and designed it with strong coordinated frequency signatures on the top and back. You wouldn't think that would have a strong bass but the effect of the tuned plates and shallow depth was to couple the two really strongly. The bass really is deep and strong, and very well balanced with the rest of the resonances. Plus what resulted was a 17" that had the comfort of a smaller guitar, not as much to drape the arm over.

That's basically correct, but it's just one factor contributing to the total tone profile. Nobody completely understands why acoustic instruments sound the way they do in all details.

Here's a quote from another builder Martin Keith (The Auriole is one of his flattop models):

"For any acoustic enclosure, the area of the soundhole is vitally important to the tuning - in fact, it is the single most important variable, and small changes can make a big difference. The Auriole soundhole is carefully sized to maximize the bass response of the guitar without compromising treble clarity."

Somebody has made an archtop with adjustable soundholes. I think D'Aquisto did it. You can slide a thing to cover part of the hole. I always wanted to try that.

There is much to be learned from the audio crowd. Anyone who has built high end audio speakers knows that designing horns and ports is an art and a science. Ports are one thing and have a pronounced effect on the sound, put that same area of aperture on the side, and it's very different. I still haven't figured out why it seems to have such a small effect on the standing wave or sound pressure.
Fun with physics!
David

[targuit]

Do things like beveling the surface of the top where the right arm rests affect tone significantly? At least in principle that beveling could make the guitar more comfortable for the player.