Yamaha acoustic Ratrod project *Mods*

[HandofDoom21]

This thing is a labor of love that I undertook over the last week. Re-voiced the top sanded all the finish off and flat blacked it. Ha. I also re-voiced the bracing...shaving it down A lot in the process. The 2 sound ports on the side also aids the uniquely loud and focused voice it ended up with. Anyone else thrash an older guitar for fun? This is the first of many in a series I am putting together for sale eventually. If interested I can put up a short vid on youtube. Here's some images in the meantime of how it turned out. Thanks for taking a look. Action and setup is spot on w a little relief and measuring a little under 2.5mm at the low e and a tad bit lower on the high E. I dressed the frets and lowered the saddle a bit as well. I am a very amateur repairman / modder but have been playing guitar for nearly 20 years. I setup and did the relic job on that all mahogany LP too.

[mirwa]

That is a lot of material you have moved from the front sides of the x brace

[HandofDoom21]

It sounds awesome though!!!! Does anyone know exactly what removing that wood does? Bass response is still pretty good...opened up the midst a bit and really rings out loud.....I gotta get my iPad to record stuff eventually.

[charles Tauber]

Originally Posted by HandofDoom21

It sounds awesome though!!!!

The issue is longevity. It isn’t difficult to make a short-lived nice sounding guitar. The trick is to make a nice sounding guitar that will structurally survive for a “sufficient” duration.

From a structural point of view that is THE wrong place to remove wood from X braces. In as little as a year or two you can expect to see the bridge begin to rotate into the sound hole, something that often begins to happen in decades.

[HandofDoom21]

What's the correct place to remove brace meat then?

[charles Tauber]

Originally Posted by HandofDoom21

What's the correct place to remove brace meat then?

That's kind of the point: there is no one place on all X-braced guitars that is THE correct place.

The guitar's response is the result of a combination of mass, stiffness and damping. One a finished instrument, you have input on the mass and stiffness.

One is then attempting to create a causation that if I do "X", it will result in a (desired) change in the sound "Y". That starts with identifying what change in sound you want to effect. From there, you'd attempt to identify what would need to change about the mass and/or stiffness of the existing individual instrument so that that specific change in sound would result. To some extent, that will be different with each individual guitar.

The flip side of that is that while you are making those changes not to compromise the structure/longevity of the instrument. That requires having some understanding of where the stresses are highest. One can to some extent compare what exists on that individual instrument compared to other instruments of similar design and construction. Doing so can provide some insights. For example, if a particular guitar has an X-brace that is 1/4" taller than on similar instruments that sound "better", that might be a starting point.

In a beam of rectangular cross section, the mass of the beam is proportional to its width. The stiffness of the beam is proportional to the cube of the beam's height. That is, if you double the width of a guitar brace, you double the mass of the brace, while doubling its stiffness. If you double the height of the brace, you double its mass but make it eight times stiffer. Relatively small changes in brace height can have big changes in stiffness. The material you removed from the X brace took out relatively little mass but significantly reduced the stiffness in that area, effectively creating a hinge. The area of the top above the juncture of the X brace is largely structural and has significantly less influence on the sound the instrument produces.

For the lower bout, you can assess the overall stiffness of the top and bridge. One way of doing that on a finished instrument is to press on each side of the bridge, on the wings. Press both sides equally and then alternating pressing on each wing and observe how the top moves. With experience, that can give some insight into how stiff the top is and where one can reduce stiffness. Depending on the specifics of the instrument, that will likely be to reduce excess bracing from the finger braces, the transverse braces and possibly scalloping the arms of the X brace in the lower bout: more difficult areas to reach through a sound hole.

Then there are other avenues to look at, such as changing the sound hole size, which can include adding sound ports. You could also experiment with adding weights (mass) to the bridge, or removing mass from the bridge. (The bridge is the heaviest, stiffest brace on the guitar top.) Adding mass can be done non-destructively, removing mass, less so. And so on. The guitar is the sum of its parts. Each part contributes to the response of the instrument.

It depends upon what you have and what change in sound you want and being able to make a cause and effect result between what you change and getting what you want. Randomly carving things produces random results, some of which can compromise the structure of the instrument.

EDIT:

Looking at your photo through the sound hole, IF I was going to alter the bracing, I'd start by progressively reducing the heights of the finger braces and then the transverse braces in the lower bout. They are likely taller/stiffer than they need to be (aka over-built).

[edcmat-l1]

Those poor guitars......

[HandofDoom21]

Such a great amount of knowledge man. Thank you so much!!! Yeah I found the soundport yo be so easy and really added volume.

Also.....both guitars were already compromised when I got them! The yamaha had a hole and the finish on the LP was worse than it is now ahahaha. Cheapie projects to have fun with and learn is what it's all about.

[HandofDoom21]

Here's another one! It started life as an Abaline made by Samick. Enlarged the sound hole, bone nut and saddle....did the fretwork....arm bevel....added a soundport....shaved the braces down like the other one....refinned it kinda like a Martin streetmaster and added some MOP. It's ply mahogany I'm pretty sure but after the refin process it's got some Koa vibes. Ha. Sounds great. Should be posting both on Reverb soon w videos. Thanks for taking a look.

It's been played by many and I'm getting good feedback on my mods. The meat I took from the braces were inspected by a luthier and they said it would hold up for sure. I modeled them off Olson/ Lowden...etc....Look at all the boutique brands and builders doing really thin brace work. Both were tap tuned during the mods as well....pretty crazy how good an inexpensive guitar can sound w a little work.

[HandofDoom21]

I just carved a modified soft V neck into the 2nd guitar pictured. I'm having a lot of fun with this!!