Guitar #110 - A little experimentation

Construction and repair of Classical Guitar and related instruments
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Andy Culpepper
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Guitar #110 - A little experimentation

Post by Andy Culpepper » Sat Aug 10, 2019 12:00 am

Hey all,

I haven't been on the forum here in quite a while but here goes a good old fashioned build thread. My classical guitar making has been going really well, and you can find some nice videos of my guitars that Guitar Salon International has produced, on their YouTube channel. Basically I've been really happy with my classical guitars, and getting good feedback too. BUT, there is always room to push the boundaries and try to go even further, right?

I'm trying a couple of different ideas on #110. The things my guitars already do really well are clarity, separation, beauty of tone, overtones, very strong trebles and good sustain and projection. The main thing I am wondering if there is room for a tiny bit more volume in that mix. I don't want to lose any of the beauty and poetry of the sound though, and I know that raw volume can come at the expense of the exquisite purity of the sound. I do NOT want a guitar that is super fundamental-heavy, thuddy, twangy or percussive. The notes need to bloom out with the same richness, sustain and emotional, voice-like quality.

The main thing I'm going to do is make the top quite a bit thinner, with some small of but notable modifications to the bracing. I'll get into everything more as we move along. I've selected a 20 year aged Adirondack Spruce top that is some of the stiffest Spruce I've ever used in both directions. But with the right thickness I'm hoping it will really sing. It has some really beautiful qualities visually and tonally. Normally I would make a Spruce top around 2.4 - 2.5 mm thick, with the edges of the lower bout thinned out to 1.8 - 2.0. This one will *probably* be under 2 mm all over, but I can't tell until I start thicknessing it. It's going to be a very light guitar overall. The Indian Rosewood back will also end up below 2 mm, and I'm going to try 4 braces on it instead of 3.

This guitar will also be available for sale when finished, unless someone reserves it during construction.

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ernandez R
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Re: Guitar #110 - A little experimentation

Post by ernandez R » Sat Aug 10, 2019 3:14 am

This will be fun. I read years of your posts over to the foro and really get a lot out of what you share.

So how dense is the topwood and how will you adjust compaired to your usual top material?


HR
I hate sanding wood or anything else for that matter I just happen to be good at it...

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Michael Lazar
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Re: Guitar #110 - A little experimentation

Post by Michael Lazar » Sat Aug 10, 2019 1:29 pm

Hey Andy. I expect this experiment will turn out well. I also built a guitar from Adirondack as an "experiment". The top was torrefied , however, I don't believe that makes any significant difference. The thickness is 1.9mm with no graduations anywhere. I was very happy with the result. The fellow that bought it was playing an Australian made "Smallman" type with a carbon fiber/balsa lattice under a .7 mm spruce top. This guitar matched the volume but with much more traditional tonal characteristics.
DF~127 Top.jpg
DF~127 Rosette.jpg
DF~127 Interior.jpg
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Andy Culpepper
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Re: Guitar #110 - A little experimentation

Post by Andy Culpepper » Sun Aug 11, 2019 12:58 am

ernandez R wrote:
Sat Aug 10, 2019 3:14 am
This will be fun. I read years of your posts over to the foro and really get a lot out of what you share.

So how dense is the topwood and how will you adjust compaired to your usual top material?


HR
The density is around .44 grams per cubic cm. It's on the high end for what I would normally use but nothing crazy. And it is very stiff. I was already going to go for a thinner top no matter what wood I used, and I have a feeling this one might go under 2 mm. It's still going to be very traditional fan bracing, with open harmonic bars, but I'm going to do something a little different with multiple cross-grain patches. Thanks for reading :)

Michael, great looking guitar, glad the Adirondack worked out for you!

Dave M
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Re: Guitar #110 - A little experimentation

Post by Dave M » Sun Aug 11, 2019 4:58 pm

This will be interesting to follow.

I imagine you will have to increase the height of your fan bracing somewhat to maintain the right overall stiffness of the top...?
Dave

ernandez R
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Re: Guitar #110 - A little experimentation

Post by ernandez R » Sun Aug 11, 2019 9:11 pm

Ok, so you inspired me to weigh the two tops I recently glued up and thinned: .42 gm/cm3 and .46gm/cm3

Ill post the gorry details in my MK-IV build thread.


HR
I hate sanding wood or anything else for that matter I just happen to be good at it...

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Andy Culpepper
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Re: Guitar #110 - A little experimentation

Post by Andy Culpepper » Mon Aug 12, 2019 12:07 am

Dave M wrote:
Sun Aug 11, 2019 4:58 pm
This will be interesting to follow.

I imagine you will have to increase the height of your fan bracing somewhat to maintain the right overall stiffness of the top...?
Hi Dave, I'm planning on leaving the fan braces more or less the same dimensions as usual. The design I've been using has more stiffness than is strictly necessary in the center of the top, which may be part of the magic. It will be interesting to see what happens when this design is pushed a little closer towards that mechanical failure point. There are makers who have navigated right to the edge of that point and makers who have stayed well clear of it, and good results can be had either way. I will be adding a couple of extra very thin cross-grain patches in front of and behind the bridge to help maintain the top doming with minimal weight/stiffness.

khs
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Re: Guitar #110 - A little experimentation

Post by khs » Mon Aug 12, 2019 2:37 am

Andy Culpepper wrote:
Mon Aug 12, 2019 12:07 am
Dave M wrote:
Sun Aug 11, 2019 4:58 pm
This will be interesting to follow.

I imagine you will have to increase the height of your fan bracing somewhat to maintain the right overall stiffness of the top...?
Hi Dave, I'm planning on leaving the fan braces more or less the same dimensions as usual. The design I've been using has more stiffness than is strictly necessary in the center of the top, which may be part of the magic. It will be interesting to see what happens when this design is pushed a little closer towards that mechanical failure point. There are makers who have navigated right to the edge of that point and makers who have stayed well clear of it, and good results can be had either way. I will be adding a couple of extra very thin cross-grain patches in front of and behind the bridge to help maintain the top doming with minimal weight/stiffness.
Would you let me know what wood you usually use for the cross-grain patches?

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Andy Culpepper
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Re: Guitar #110 - A little experimentation

Post by Andy Culpepper » Mon Aug 12, 2019 11:19 pm

khs wrote:
Mon Aug 12, 2019 2:37 am

Would you let me know what wood you usually use for the cross-grain patches?
Most often I will use Spruce.

Some more pictures...

A little rosette math
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Cutting channels for tile with circle cutter
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Routing out with Dremel
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Inlaying the tiles with a thin veneer strip because the channel ended up just a little too wide
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Not my best rosette work ever but it will do!
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Getting ready to glue up the heel
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Fitting the back braces. The back is pretty thin and I'm trying out a 4 brace configuration to tighten things up a little.
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TheEvan
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Re: Guitar #110 - A little experimentation

Post by TheEvan » Tue Aug 13, 2019 9:49 am

I love your rosette. Distinctive and unique without being trendy

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Andy Culpepper
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Re: Guitar #110 - A little experimentation

Post by Andy Culpepper » Tue Aug 13, 2019 12:41 pm

TheEvan wrote:
Tue Aug 13, 2019 9:49 am
I love your rosette. Distinctive and unique without being trendy
Thanks, Evan! I would be remiss if I didn't mention this rosette as an inspiration. I first saw it on my teacher's 1979 Ramirez 1a flamenco, and it also inspired my headstock design. https://www.kentguitarclassics.com/wp-c ... 00x395.jpg

Gregory
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Re: Guitar #110 - A little experimentation

Post by Gregory » Tue Aug 13, 2019 6:43 pm

Why 4 braces on the back??what is the difference??

riffmeister
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Re: Guitar #110 - A little experimentation

Post by riffmeister » Tue Aug 13, 2019 6:52 pm

Andy, in addition to the superlatives of sound/response you listed for your instruments, I personally put evenness of sustain (said differently, minimization of 'short' notes) high on the list. And higher than eking out a little more volume. An opinion of mine based on my personal experience as a guitar player (not builder) is that thinner tops tend to accentuate the unevenness of sustain (said differently, make the 'short' notes more noticeable).

Good luck on #110 and beyond!

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Andy Culpepper
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Re: Guitar #110 - A little experimentation

Post by Andy Culpepper » Tue Aug 13, 2019 11:58 pm

Gregory wrote:
Tue Aug 13, 2019 6:43 pm
Why 4 braces on the back??what is the difference??
Recently I was talking to a customer of mine, and he mentioned that when he held the guitar tightly against his chest so that the area between the upper and middle back brace was prevented from vibrating freely, he thought the guitar sounded better. It got me thinking and interested in experimenting with a 4th back brace. I actually wanted to try 5, Dominique Field style, but chickened out. Speaking of Dominique Field, I think he is doing some cool and interesting things. I had a mini-revelation in my classical building when I tried the idea of using a ton of side reinforcements. I use 24 on every guitar now (not as many as Field) and for some reason it has really helped get the bass response where I want it to be. Did not expect that outcome but it's very noticeable.
Andy, in addition to the superlatives of sound/response you listed for your instruments, I personally put evenness of sustain (said differently, minimization of 'short' notes) high on the list. And higher than eking out a little more volume. An opinion of mine based on my personal experience as a guitar player (not builder) is that thinner tops tend to accentuate the unevenness of sustain (said differently, make the 'short' notes more noticeable).

Good luck on #110 and beyond!
Thanks riff, I agree. There is a strong chance I'm being too greedy here, and that this guitar will be a slap in the face and a reminder that a bird in the hand is worth two in the bush. I would happily return to what I was doing before, but I think these experiments can teach you a lot whether or not they fully succeed.

Tim Buckley
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Re: Guitar #110 - A little experimentation

Post by Tim Buckley » Wed Aug 14, 2019 10:14 pm

Hi Andy,

I'm learning so much from this thread, and will watch this build very closely. I'm currently in the first stages of making a thin-topped guitar using some sitka spruce that was sent to me by mistake a few years ago (440kg/m3), so quite similar parameters apply.

Your insights into the side and back configuration you're trying out are invaluable.

For me it's guitar #2 rather than #110, so a very different sort of learning curve!

Tim

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