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Howdy all. On a recent build, actually the prototype of my Odalisque shape, I decided to push the limits if a lightly-built guitar, just to see, or rather hear, what the end result would produce. Well, in general, it's a very responsive, warm, woody-sounding guitar, but is considerably lacking in the higher frequencies, especially the lower strings. The low E sounds straight up thuddy. Does anyone have suggestions for getting some sparkle back into the spectrum, now that the guitar is complete? I suspect the lack of sparkle is caused by over-thinning the lower bout. The back and sides are quite thin as well.

Thanks in advance for your input.

Ken

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Mountain Song Guitars www.mountainsongguitars.com

I find that sequins are cheap way to add sparkle to most anything

I see....He went to Jared.

Heh, I set myself up for that one.

Filippo -- Sure. Here's a shot:

Sizewise, it's similar to a 000, though slimmer in the UB and waist/LB transition, and a bit wider through the LB. Also, I kept the back-to-front taper to only 1/2", going from 4.25" to 3.75" at the neck join. Lutz top (.095" ish) and mahogany B&S (.075"). I seem to recall sanding the LB perimeter down to around .085". Bracing is red spruce, tall and skinny all over. Traditional scalloped X, with the main X braces .25" wide and .625" at the intersection. All fingers and tone bars are 3/16". 4" soundhole, ebony bridge (16" radius across whole bridge, per Somogyi/Mayes), brazilian bridge plate. I'm not finding the bridge weight in my notes, but it's probably in the 25-30g range. Hope this info helps.

K

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Mountain Song Guitars www.mountainsongguitars.com

From all you've told there, my instinct points toward the bridge. Maybe replace it with something lighter and lower damping? Could be the effects are amplified on a more responsive box. Brazilian is always nice, but there are plenty of other good woods. I'd probably do padauk. But also could use pecan, osage orange, black locust, mesquite, wenge... maybe even go Trevor Gore style and try walnut for ultra-light. But if you do replace it, start by changing to wood or plastic pins for a quick weight reduction, and then chisel wood off of the current bridge and see how the tone changes as it lightens and loosens.

I do like the full width arch style, but I only leave it full height at the front edge, and taper it toward the back to reduce weight as much as possible. Dense woods like ebony are really stiff anyway, so it doesn't take that much height before it's effectively rigid when combined with the thickness of the top and bridge plate underneath. Looks like you have the Somogyi style scoops already, which eliminate some fat.

Oh, and one more thing... are the strings fresh? I had an entertaining experience recently with a dull sounding low string that looked clean, but turned out to be all dented up along the bottom from the frets

+1. My Lutz-topped guitars seem to take longer to open up compared to Sitka or White.

Pat

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

Great suggestions, Dennis. I did put fresh strings on, hoping that was part of the problem. Helped a little, but the low E and A are still thuddy. I may try lightening up the bridge some, but would be reluctant to replace it altogether. I'm really hoping I may be able to get some high end back by making the top a bit more rigid, eg, adding a couple of extra finger braces, maybe extending from the lower tone bar and perpendicular to it. It'd be an interesting experiment, anyway...

Filippo -- I completed the guitar last April, and it has probably 80-100 hours of play in it.

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Mountain Song Guitars www.mountainsongguitars.com

You could try a small brace behind the bridge, AKA a Musser bar, Mario tone enhancer, or whatever it's called these days.

I significantly underbuilt my first actual guitar, thinking I was being clever with my bracing scheme. It had the same issue, but eventually the trebles did develop nicely. This surprised me a bit. It sounds very nice now. Therefore +1 on the opinions that break in may well improve the trebles.

I've seen some lightly built guitars that had good 'sparkle' as well, so I'm not sure if it's _just_ top stiffness. I think that getting the bracing and the top working well together has a lot to do with it, and that might actually mean that you'd need to _reduce_ the bracing on a thin top, which is a no-go. I have to wonder if Dave Hurd's deflection mapping might help; it's too late for 'free' plate tuning, but he seems to end up in about the same place.

Lightening up on the bridge should help, and you may need to think about replacing it, since it can be hard to get an ebony bridge light enough without losing structural strength.

It might be somewhat "left-brained" for you, but a tap response showing the frequencies of the main modal resonances is a good diagnostic tool.

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

Trevor, although my background is in fine art, my brain swings both ways, man! Enough so that I've been devouring your books since purchasing them a couple of months ago. Sadly, this newfound knowledge came a little too late for this guitar... That said, I did do some Chladni testing on it earlier tonight. Here's what I found: the main air resonance is 104.4 hz, the main top resonance at 193.5, and the main back resonance is 224. I also got a strong response at 378, and another at 470. What this all means, I'm still parsing out.

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Mountain Song Guitars www.mountainsongguitars.com

From the numbers you posted I wouldn't consider that to be an "on the edge" top for that size guitar. I think .075 is a little thin though for a mahogany back though, with out having felt it.
You might double check your set up. Is the nut well seated, slots, etc...

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Jim Watts
http://jameswattsguitars.com

From your numbers, the back could have been a little stiffer, but, generally, what Jim said.

What finish did you use?

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

I`m by no means the expert, but from your photo it seems to me that the soundhole is too large for the upper sizes and dimensions.
Is a 4" soundhole the size you started out with from the plan/idea that you had at the design stage?
My 000`s (from the Antes Grand Auditorium plan) have soundholes of just under 3 7/8" (51/64" to be exact).
It seems like the proportion changes may have an effect on how long those bass frequencies have to bounce around inside the soundbox before escaping out through the soundhole having too quick a decay(hence the muddy sound).
Maybe I`m out of place, and hopefully others that know far more than I do will chime in.
Coe Franklin

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Give me 50 cents worth of regular.
Check my oil too, if you don`t mind,,,

The pitches of the low order modes often don't do a very good job of predicting 'sparkle'. I've seen a few marshmallow guitars that had surprisingly good high end sound, and some with high 'main top ' and 'main back' modes that were as flat as yesterday's souffle. The low order mode pitches have a lot more to do with low-end sound than with the high end, IMO.

Quite right. The OP suggested that this was a very lightly built guitar that might be too "floppy". That doesn't appear to be the case; but if it had been, the imbalance between the lows and highs might well give the impression of missing "sparkle".

High damping is one thing that kills sparkle, and thick polyester finishes can certainly do that. My experience is that a Tusq saddle gives more "sparkle" than bone, so that might be an option, too.

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

Thanks for all your replies. I overcame my righteous indignation at some of your suggestions to check nut/saddle fit, etc , and to my surprise, I did find that the saddle I was using is very porous, and seems to have a much lower "Q" than a tusq saddle. I'm not sure why I deemed it acceptable in the first place, but upon switching it out with the tusq one, I'm hearing a definite improvement. It's still not as chimey as I'd like it, but I'm starting to think it may just be a combination of a few of the issues you all have mentioned that can hopefully be improved upon going forward.

Thanks for your input! Oh, here's a shot of the old saddle.

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Mountain Song Guitars www.mountainsongguitars.com

Oh, to answer Trevor's question, the finish is .005" EM6000. Also worth noting is that it doesn't have a pickguard. Any thoughts on what effect adding one might have? On one hand, it seems it might "tighten up" the top, in the event it is a bit floppy, but on the other, it seems it would greatly increase damping of the top. Oy! The quest continues...

Ken

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Mountain Song Guitars www.mountainsongguitars.com

I rarely put pickguards on guitars, but when I do, I can hear the difference. Very slight and really can only be heard on an immediate A/B test; sounds like slightly older strings.

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au