Oops...I've hit a tipping point tinkering with my D-18

[Roger Johnson]

Any advice to help me restore the tone to my 1974 D-18 would be greatly appreciated, thank you.

I have inadvertently tinkered with its innards to the point where it now sounds airy with no meat or body or fullness to the sound. And there’s too much empty open flat echo inside. I have tried different strings to no avail and finally had to accept that the problem lies within the box.

Here’s what happened (he said hanging his head sheepishly…):  Over time I have been sanding some of the straight top braces to resemble scalloped and the two rear bottom braces to reduce their height. Up to this point these efforts had produced a nice fuller sound with more bass.

However, the other day I hit a tipping point. I sanded more of the top braces, and used a contoured form to sand down more of the rear bottom braces. I also used a small very sharp chisel and sandpaper to remove about 50 percent of the popsicle brace at both ends, but not in the middle. When I restrung I had lost the full round warm sound I once had.
Two other data points: years ago the soundhole had been enlarged by ¼”, and a rosewood cross-brace had been glued to the end of the bridge plate to coax out more bass.
Is there anything I (or a professional) can do to get back the sound I had a few days ago? Add back some mass to the braces (top, bottom,and/or popsicle)? Or have I turned my beloved instrument into kindling?
Thank you, Roger

 

[Vic Farrell]

" a rosewood cross-brace had been glued to the end of the bridge plate to coax out more bass." I 'm not sure if that really helped anything. Rosewood is a heaver wood as compared to spruce. and therefore may have given you less bass. As to the shaved braces!! I would say that if you have over scalloped then replacement of the braces is the best solution. At least the finger braces to start.It is always best to ask advice about something you are unsure of before going a head. I have been repairing,restoring and tuning guitar tops for 20+ years and I still will ask my fellow luthiers about things i am uncertain of. There is one more thing. I call it intuition. Use it. It is a deep gut feeling that comes when you are heart, soul and mind focused on the job you are doing. It sounds to me that you were not listening to it. otherwise you would have stopped before you went to far. I know it sounds crazy but this is the only way I can explain what guides me in those things. you sand or plain, stop, tap, tune, listen, close your eyes and listen again. and do it all over again. As you work listen to that intuition talking to you and follow it. Nuts ah? what can I say.
I hope you can do what I am suggesting or know some good luthier who can. It will not be cheap though.

Vic F.

[Ned Knepp]

In my opinion trying to add wood to the braces would add to the "damage done". I think the guitar should have new braces installed and then be graduated for the sound you want.

Thinning the braces also weakens the guitar structurally. It could be that you will save yourself from a heart breaking failure in the future as well as get you the sound you want but I think I would find a good repairman to do it.

Ned

[Eclipse Wizard]

I agree with Ned. Installing new braces is most likely the best solution. And to that point I would install them one at a time... I do indeed think that you should be congradulated for attempting to tune it yourself.

[Pierre-Antoine Roiron]

I don't see any other way : removing top and re-install new braces.

[Jim Bancroft]

I'd chalk it up as a learning experience, and hopefully you have learned not to mess with the interior bracing, especially if it sounds good as it is.
It's going to be more effort than it's worth to get back to the tone the guitar should have. You would have to pull the top or back and rebrace it to get anywhere with an improvement. Also the 70's Martins already have low profile back braces, you don't want to lower them any.

I've never understood why people want to modify a guitar that already sounds fine, trying to make it sound better.

Jim

[Roger Johnson]

Thank you gentlemen for your replies. I picked up the old D-18 clunker as a fixer-upper, it had a number of problems at the time. By contrast, I acquired the other guitars in my modest collection specifically for their sound and would never attempt to modify them.
But this one tempted my tinkering spirit. I have experience as a finish carpenter working with cabinet makers, and a love and curiosity for these wooden boxes we play, and this guitar seemed the perfect candidate as a learning experience. Except for this last time, the fixes and modifications have worked well and I was very pleased with the results and clearer, more open sound.

Unfortunately this last time I did not test after each procedure, but sanded the top, back, and popsicle braces in the same session, and therefore don't know which one or combinations tipped the sound.

I will continue to tinker and experiment. This has been a wonderful learning experience so far. Thanks again for your thoughts, Roger

[David Houchens]

Well since you're gonna open er up anyhow, nows your chance to rebrace with taller 1/4" bracing and a small maple bridge plate. Also I would opt for changing the long back braces to be shaped narrow and tall. similiar to the other two but taller.
A mid 70's D18 doesn't command a hugh resale price anyhow, so make a 1935 cannon while you're in there.
I really enjoy hotrodding these guitars. It probably won't increase the value any but you can really have a player that will turn heads. In the hotrod/ motorcycle world, we called them sleepers. Might not look like much but be careful bettin against em.

[Vic Farrell]

Just for the record. I have completely re-braced a top through the sound hole. So it is impossible. Taking off the back may make it easier to work on but it can be done through the sound hole. You might consider this a new advanture and challenge.

Thanks
Vic F.

[Pierre-Antoine Roiron]

Very impressive Vic... how did you manage to unglue the braces that go through the kerfing? How long did it take you?