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I know of two builders in Seattle who make the middle thicker and taper at both ends.

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Pat

I'm kinda glad my classical only has five strings right now!

Alex

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"Indecision is the key to flexibility" .... Bumper sticker

The one and only reason a guitar is tapered is because Martin did it way back in the 1800's.
or because the first guitar was a derivative of the lute. They were bowl backed and as such, they tapered from back to front. The guitar makers of ye olde luthiers guilds continued that traditional look in their own way.
This is all just speculation of course. I think.

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http://www.CostaGuitars.com
PMoMC

This thread is comedy gold.

I think Steve Sheriff (Edwinson guitars) builds non-tapered. The page discussing it seems to be gone though, with the new web site still under construction.

For me, tapering is done for 3 reasons:
1. That's how most people do it, and I can't think of a good argument against it.
2. Comfort. You get the same internal air volume with less body depth at the waist.
3. It looks nice. The body width is narrower at the upper bout, and the neck width and thickness taper. Almost creates an optical illusion of the body tapering the opposite way if you make it flat. A very slight taper (like 1/4" difference) looks more flat than flat

How can a taper not be less volume than non-tapered?

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Thank You and Best To All

Certainly it's less air volume if you just decrease the neck depth. But if you decrease the neck and increase the tail in a way that maintains constant air volume, then the tapered one will be shallower at the waist. Reason being, the waist is above the mid-way point, plus the lower bout is wider than the upper bout so more depth there makes a bigger difference in air volume than at the upper bout.

But of course - got it.

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Thank You and Best To All

McPherson makes a guitar that is thicker in upper bout and tapers thinner toward the lower bout.


Sent from my walkie talkie using Tapatalk

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"After forty-nine years of violin building, I have decided that the search for a varnish is similar to the fox hunt. The fun is in the hunt."
Jack Batts Maker and Repairer of Fine Violins

You have to go back to early Guitars to find a reason. Even in the 17 th century we find Guitars that are deeper at the bottom block. There are some later Guitars that taper both to the top and bottom block.
Comfort isn't a good enough reason. The difference is negligible, certainly not enough to convince me that is the reason. Besides, there is a slight taper on 17 th century Violins (same direction) and that instrument isn't held against the body.
It's not for structural strength either. It's because. . . that's the way nature intended Guitars to be made. It's an aesthetic. They didn't like straight lines or perfect symmetry, probably because it appeared too harsh to their eye. The Violin fingerboard tapers on the underside as it goes over the Violin body. There is no reason why that should be the case other than weight or appearance. It's unlikely to be weight because many baroque fingerboards were made of Box veneered Spruce. You would be saving a few grams at most. The heads on early Guitars tapered in thickness. Thicker at the Nut end. There is no structural or mechanical reason for that to be the case. The friction Pegs (they tapered as well!!) weren't any different, whether they were positioned near the Nut or at the very end of the head.
On the vast majority of Guitars the Neck is thicker at the 9 th fret than it is at the 1 st fret. But Necks that don't have this feature play perfectly well. The fretboard tapers with the line of the strings. Practically the only place where I can find a mechanical reason for the taper (other than the Pegs). So everywhere you look on a Guitar they were intent on avoiding straight parallel lines.
Just like a tree.

When I first saw this thread, my gut response was "Why is the sky blue?" I thought for sure there was a logical answer, and I'm sure at one time someone explained to me why the sky was blue, and even if I can't remember the entire answer it was grounded in science (seems like the light spectrum had something to do with it). I never even questioned the idea of the taper simply because I figure that it evolved over time for a valid reason; hope it had nothing to do with the size of the roasting pan or goats. I have to admit that I have thought the taper on the few builds I've attempted isn't really much from one end to the other, and it would be easier to leave it out, but I think it would look weird to me otherwise. I like Dennis' responses and seems like his #2 would be one of the main reasons. Anyway it's always good to ask why. Thanks Larry.

The reason I asked is so I can understand a little bit more about guitar design and not get stuck in a world of absolute design ideas.

Martin has been making changes in their design (from what I've learned here) to add structural integrity in order to avoid warranty repair and very little to improve tone. They have a tapered body but I just built a small body guitar with very little taper (probably forgot or some other beginner error) but it sounds fine.

Would it sound better with more taper? If it will then I want to know why and make sure I get enough taper in there. If not then I want to know why so I can worry about other things.

And don't even get me started on 'tone bars.' Those things have to be stupidest things I can think of to do to the lower bout but hey that's what my mother used to always do so....

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Thank You and Best To All

I've heard that the taper reduces standing waves in the sound box by not having the back and top parallel to each other.

Still,that kinda sounds to me like an ad hoc explanation, that might have some merit, but even so, is not necrssarily the original reason.

It also increases the stiffness and resilience of the box by introducing a little tension in the structure. That seems like a better reason to me, personally, and more likely.

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Old growth, shmold growth!

Flat Back Baroque guitars taper. No curve to the Back. No tension. You have to answer these questions before coming up with a logical answer. Violins taper as well. Both of these instruments were not made in isolation, as Strad made both. You don't need a tapered Violin for comfort and I'm certainly not convinced that a few mm's less on the waist point of a Guitar will lead to greater comfort.

I'd say the main reasons are tradition, aesthetics, and probably acoustics. My student project guitars are all straight sided for simplicity. The neck area looks pretty strange with a body deeper than about 3 7/8" -- both the transition from thin neck to UB, and the comparison of thin neck to chunky body. So our body depth is 3 7/8".

I've tested a lot of straight sided guitars and I don't see a consistent big resonant peak at the mathematical standing wave freq (~1780 Hz for mine). I often find a valley there, and small to moderate peaks on either side of it within a hundred Hz (maybe the bracing throws it higher, or the moving plates shift it lower, or the standing wave can't get out of the box.) But those peaks aren't remarkable compared to others above 1000 Hz... ~1100 Hz and ~2500 Hz tend to be the most prominent for mine.

This is conjecture -- historically, maybe some guitar makers had a guitar designed or built, or 2 identical necks built, and wanted to see what more air volume would do. So they made some sides deeper at the tail, keeping the neck joint the same. It probably looked and sounded better, so the design stuck.

Inside a guitar, not all cubic inches behave the same way for the air resonances, so it's unclear whether maintaining constant internal volume is a good measure. More volume in the tail vs. the waist vs. the upper bout is likely to give different tone. Allen had a good article on air resonances in A.L., but I don't recall if he looked at body depth. I'd guess the traditional taper sounds best for some (poorly understood) set of reasons, since we don't have counter examples. Maybe Alan or Trevor knows more.

For seated playing, I've not found the combo of deeper tail and narrower waist and UB to be more comfortable. For me, the depth where the arm wraps around the LB is the main influence on dis/comfort. Less depth at the waist helps if you want to see the strings, but a thicker waist or UB isn't uncomfortable like a thicker LB is. Others would know better about standing.

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David Malicky

Could there be some benefit to reducing the air volume in the soundhole area, as this is also where the waist "pinches" the body? Could it be part of the idea of "tuning the port" much as what was done with the tornavoz and bass reflex speakers?

avoiding standing waves which would lead to wulf tones

Of course it's not the first time that this question has been asked:

http://www.maestronet.com/forum/index.p ... /?hl=taper

Variety of answers, pretty much the same as given here. The answer citing the Viola da gamba/ viola da braccio may have some merit. Perhaps this aesthetic was simply transferred to other instruments, including the Guitar.

The viola da gamba has straight sides. There is a significant taper of the back but only in the heel area. This is the part of the back that rests against the player's body, the instrument is held at an angle (much like a cello) and the taper reduces significant point bits pressing against the body.

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Expectation is the source of all misery; comparison the thief of joy.
http://redrivercanoe.ca/

True but it's not a great stretch to go from that taper to one that extends further down the rib. Perhaps it's simply a case of evolution. Primarily done on one instrument for playing position but then adapted to other instruments for aesthetic reasons.

When I first got interested in instrument building, there was a lot of talk about the importance of not having parallel flat surfaces, and minimizing flat surfaces in general. As a general rule, every surface was supposed to be curved if possible, for the smoothest possible response. I always assumed the tapered back was part of this general philosophy, which may well go back hundreds of years.

At any rate, if two surfaces of a soundbox are parallel, there *will* be a (1/2 wave) standing wave between them. Whether this is significant is I suppose open to debate. It's easily calculated by dividing the speed of sound in inches by 2, and dividing that by the internal distance. For example, if the distance between the soundboard and back is 3 3/4" then it would be: 13500/2/3.75, which is 1800Hz.

This won't necessarily cause a peak. Firstly, that's a high frequency and the soundhole is a low-pass filter. Secondly, the resonance may actually suck energy away from the bell modes of the soundboard itself. I do think that every little bit adds up, so if one can smooth this out by tapering the back angle, it's a good idea as far as I'm concerned.

I call my current line of guitars "Heresies", because I'm basically breaking a lot of the "rules" of acoustic guitar making - including the rule of taper. Instead of attempting to follow a lot of old luthier tales, unchallenged opinions and "luthier voodoo", I'm designing my guitars to be foremostly ergonomic - and non-flat.

The Heresy 1 (pictured) is fairly small, only having about 58% of the "box volume" (cubic inches) of an OM. It doesn't really sound like an OM, or a dreadnought (not too surprising). Basically, it has its own unique sonic signature.

I hope to have a video out "soon" with some sound clips.
Stay tuned


Jeff

http://www.kozmguitars.com

To extend Todd's comment, there's a lot of pseudo science in guitar building. :)

Sent from my GT-P3113 using Tapatalk 2

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Under Compensated Nut!

I have a chart of most Martin guitar dimensions and that chart shows a definitive ratio of tail block to neck block of .78125. So their 'M' Grand Auditorium (or OOOO) with a tail block of 4.00" has a neck block dim of 3.125". That ratio stays consistent through their entire range of guitars from 'O' to 'OOOO'. So for whatever reason, Martin seems to think that ratio is, somehow, important to their guitar building spec's.

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Thank You and Best To All

I personally LOVE different Jeff, great to see some thinking outside the 'box'.

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Thank You and Best To All

Jeff,

I see you'll be at the NW Handmade Musical Instrument Exhibit. I'm eager hear your guitars!

Pat

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formerly known around here as burbank
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http://www.patfosterguitars.com