Repair of 1975 Gibson J-45

If you have a string instrument of any kind that needs fixing, a mistake you made in building a new instrument that you need to "disappear," or a question about the ethics of altering an older instrument, ask here. Please note that it will be much easier for us to help you decide on the best repair method if you post some pictures of the problem.

Re: Repair of 1975 Gibson J-45

Postby Barry Daniels » Wed Oct 03, 2018 12:14 pm

And then I discovered this ugly mess. I knew there would be some damage from the previously moved pin holes, but the bridge was resting on a thick bed of glue. It looks like the glue is at least 1/16" thick and thicker in some spots. This is not good. I may have to resort to serious top repairs now. I will see what it looks like after a liberal application of De-Glue Goo.
Attachments
IMG_1138Resized.png
IMG_1139Resized.png
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Barry Daniels
 
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Location: The Woodlands, Texas

Re: Repair of 1975 Gibson J-45

Postby Barry Daniels » Wed Oct 03, 2018 12:38 pm

Also, here is a frequency spectrum of the guitar with the original bracing. The neck and bridge have been removed. I am no expert on interpretation of these graphs, but the blue line shows the guitar with the soundhole plugged with a foam insert which cancels out the body resonance (110 Hz) and the contribution of the back. The gap between the red and blue line around 230 to 240 Hz is the back's interplay with the top.

I am using a free software program called Room EQ Wizard and a USB microphone to make this plot.
Attachments
J-45 original bracing, no bridge.jpg
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Barry Daniels
 
Posts: 2002
Joined: Thu Jan 05, 2012 10:58 am
Location: The Woodlands, Texas

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