Top Too Thin (Full Version)

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Message

n85ae -> Top Too Thin (Feb. 5 2022 18:43:14)

Hi All -

Minor dilema, Good Old Dad and his best friend got interested in guitar building. He's a retired (80 year old Scientist)
and his best friend a retired Aerospace Machinist. One of the first guitars they built was this really beautiful, and "boomy"
sounding Santos replica. They got everything perfect with regard to string height, fret spacing, etc, etc. Notes are all
correct and really if you capo the guitar at say the 4th fret it sounds good. BUT open string it is terribly boomy, and
muddy. He admits to thinning the top too much, and probably made it worse by taking too much off the braces ...

So I would think under "normal" circumstances the best way to fix it would be just bite the bullet, do the major surgery
and make a new top.

Is there anything doable in the way of for example building up the braces, or anything like that? Or is this a lost cause to even try to pursue?

I suspect it is a lost cause, but as is the guitar is a bit annoying to play because of these issues.

Thanks,
Jeff



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El Burdo -> [Deleted] (Feb. 5 2022 20:38:52)

Post has been moved to the Recycle Bin at Dec. 22 2022 15:37:58



n85ae -> RE: Top Too Thin (Feb. 5 2022 20:45:58)

No, he's not building guitars at the moment, so it's out of the question to do that. I'm curious to see if there is a fix, that is possible short of remaking the top. I understand that making a new top is the correct solution, but it's just a question to see in a situation like this if there are any workaround solutions.

This is a guitar he made for me as a gift, but it sounds bad so I don't play it :)

It's a strange situation admittedly. Basically I want to make it better, but without him knowing.



RobF -> RE: Top Too Thin (Feb. 5 2022 21:16:11)

I’m wondering if trying light gauge strings would make a difference? Or just messing around with different strings, in general, might help.



Tom Blackshear -> RE: Top Too Thin (Feb. 5 2022 21:34:20)

Could you put up a strutting pattern of the top for me to see what you did?

If you can, then I would like to know how thin the top is in different places from the middle of the top to the outside edges. Thanks.



Pgh_flamenco -> RE: Top Too Thin (Feb. 5 2022 22:06:11)

If you put a bright light inside the guitar and take a picture of it in a dark room you might get a good idea of the strut pattern. IIRC someone did this years ago on the Foro.



n85ae -> RE: Top Too Thin (Feb. 5 2022 22:09:02)

It's a simple, and cheap experiment. Good idea, I'll try it. At worst it just cost me a set
of strings. Thanks for the idea!

Jeff

quote:

I’m wondering if trying light gauge strings would make a difference? Or just messing around with different strings, in general, might help.



ernandez R -> RE: Top Too Thin (Feb. 5 2022 22:29:54)

5AE,

How about adding some extra fan bracing, say by glueing one between each of the exesting sound bars. Do one at a time to see if you are going the right direction?

A couple extra closing braces stratigicly placed as well?

A bridge of higher mass might help?

The light trick mentioned up thread would for a photo would shed some light too.

Nice looking guitar regardless.


HR



n85ae -> RE: Top Too Thin (Feb. 5 2022 22:30:31)

Here is a link to the PDF of the Build Log for the guitar Dad built, lots of pictures and notes

Santos_Build_Log.pdf



Tom Blackshear -> RE: Top Too Thin (Feb. 5 2022 23:23:56)

I don't find a clear plan to work with and it seems you are not close enough to being able to supply an exact copy. My understanding would be to have a clear copy and actual top thickness, as a guide toward making things work.

The older master plans are tricky business for novice builders to fool with, as they take a certain amount of tweaking to make them work right. The thinner the top the harder the build, as there will always be a hole somewhere to make you think there is no solution for a fix.



RobF -> RE: Top Too Thin (Feb. 6 2022 1:10:12)

Tom,
There’s a picture of the plan he used on page 17 of the build log. It’s a basic seven fan no closing bar pattern, not that dissimilar to what Reyes used, but without any bridge patch. From what I could see in the log, the guitar doesn’t look under built as far as the braces are concerned although only the builder can answer how the top was thicknessed.

Honestly, before any surgery is done, either major or minor, can something be posted that sonically demonstrates the issue? I mean, different players have different likes and dislikes for what they want from an instrument and there is the possibility the player and guitar are just not a good fit. But regardless, it just seems to me the internet isn’t the right place to diagnose this and the kind of suggestions coming out could be very intrusive and there is a real danger of many of them also being what could be called over-the-top.

n85ae,
I’m going to weigh in and suggest leaving well enough alone. It’s a really pretty guitar and something to cherish, even if it doesn’t sound the way you would prefer. If your dad wants to join in on the Foro discussion then maybe something could be done. I mean, just based on the build log I could make some suggestions, but I won’t because frankly it would be disrespectful to the builder. I just don’t think this is the way to go about this. It’s too much. I think you’re right in fearing feelings could get hurt. Is it worth the risk?



n85ae -> RE: Top Too Thin (Feb. 6 2022 2:13:49)

These are fair points, and the one thing I had not considered was trying a lighter string. I know my Dad was a bit
disappointed and suggested he had gone too far with thinning the top I believe he said it was thinned to 1.7mm BUT
I am not really sure my memory is right. Aside from that I know they stayed pretty close to the plans

In any case, I am sure that he would like that people were seeing his log for the build. They were really invested in
building guitars for a while, and I'm not sure how many they built, but the Hauser he built actually came sounding
really nice. I think they spent as much time doing calculations, and building tools (side bender) and actually building
the guitars.

Thanks,
Jeff



RobF -> RE: Top Too Thin (Feb. 6 2022 2:43:02)

I could tell from the log they were really having a lot of fun and they were also taking it pretty seriously. I hope he’s able to continue with this. Yeah, 1.7mm is pretty thin, depending on the wood. I noticed in the log he mentioned he was concerned the guitar might sound a little too boomy, so you both picked up on that.

Maybe you can convince him to join the Foro. His buddy, too! Then if anything does get altered it will be with his blessing, and also likely done by his own hand. That would be the best outcome, I’m thinking.[sm=Smiley Guitar.gif]



bftobin -> RE: Top Too Thin (Feb. 6 2022 20:48:52)

Has anyone tried adding some weight to the top for this type of problem ?? There is a product called poster-adhesive that is a little like modeling clay but is sticky. It won't damage the finish, but it stays where you put it. Perhaps a little weight will give more power to the top.You can start by placing it or several pieces on top of the soundboard in the lower bout. If it works, place it on the underside. Non invasive experiment.

Brent



Echi -> RE: Top Too Thin (Feb. 7 2022 0:00:44)

I once used to have a similar problem with an old guitar which was partly addressed by gluing a couple of flat struts, like 15 mm. X 0.5 mm thin which I kept thinning in some areas through the soundhole.
I am not suggesting you to do it though.



ernandez R -> RE: Top Too Thin (Feb. 7 2022 4:23:37)

Well, my comment didn’t post the other day... I don’t even recall what I wrote, but I did post two screen shots from the OP’s dads build log:





Really nice work that’s for sure. Can’t help but wonder if something besides a too thin top and bracing is going on. The thing that got me thinking along these lines was the comment about the guitar sounding fine with a capo at f4? Something not right with the nut? Not seated properly or the string slots wrong?

She sure looks nice though...


HR

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n85ae -> RE: Top Too Thin (Feb. 7 2022 21:35:12)

I have been talking to Tom Blackshear on the phone a bit, and he had a number of suggestions which I will try.

However based on this idea to add weight, I did in fact try taping together a couple quarters and sticking them to the top about 20mm above the 6th string, and 60mm ahead of the bridge at a point where if I press with a finger tip I can dampen the boomy sound a bit. The weight of the quarters in this location does seem to make an improvement ... So I think there is merit to this idea. I'm using blue masking tape, which doesn't have a lot of holding power, but seems to work well enough for an experiment.

Jeff

quote:

Has anyone tried adding some weight to the top for this type of problem ?? There is a product called poster-adhesive that is a little like modeling clay but is sticky. It won't damage the finish, but it stays where you put it. Perhaps a little weight will give more power to the top.You can start by placing it or several pieces on top of the soundboard in the lower bout. If it works, place it on the underside. Non invasive experiment.



Tom Blackshear -> RE: Top Too Thin (Feb. 9 2022 17:17:27)

quote:

Perhaps a little weight will give more power to the top.You can start by placing it or several pieces on top of the soundboard in the lower bout. If it works, place it on the underside. Non invasive experiment.


Perhaps a little blue tach will work, wouldn't hurt to try it. The top seems to be stable and might be able to take a regular hard tension string to see if the top will respond with favor.



n85ae -> RE: Top Too Thin (Feb. 9 2022 23:01:16)

Tom - I made two changes at the same time, which made a big improvement, and eliminated the boomy sound entirely. One per our call - I put the EJ46 strings on it, and they entirely tightened up the feeling and the boominess is gone. The other change is I tied the stings to the tie block using just a single hole, rather than using the double hole (12-hole tie block), This changed the break angle of the strings over the bridge.

I guess next thing is just play it a lot and see how it settles down.

Anyway, maybe the original "top too thin" wasn't so much the problem I thought?



Tom Blackshear -> RE: Top Too Thin (Feb. 10 2022 15:26:02)

Jeff,

You might check the strings out as it ages and make sure the torque is not too much as she goes. A little bend in the top between the sound hole and bridge will be normal, as the Spanish masters say that indicates a good guitar.......some humor there but perhaps outdated.



Joan Maher -> RE: Top Too Thin (Feb. 24 2023 17:21:31)

Did you ever record a video of the sound as muddy and booming sounds great for flamenco?



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