Bridge Plate and Tone

[Slight Return]

I recently did a repair on a 12 string and was very surprised at how it turned out: it sounded at LEAST as good as it did before, and while I don't have any before and after tests to prove it, I swear it was a little louder and a little clearer.

The kicker is that it had a plywood plate around .115" thick. Junk wood? Sure. But still pretty thin for a 12 string plate.

I was under the impression that, regardless of material, a thicker, heavier, larger plate would sap the tone and volume for sure. This job proved me completely wrong and I was very pleasantly surprised when I got the bridge glued back on and strung it up.

I swear it sounded better, and I couldn't believe it.

The maple plate I cut out for it was about .135" thick. I also cut the plate with the grain running parallel to the strings, instead of perpendicular, in order to give it as much stiffness and strength as possible.

I also made the plate significantly larger than the original plate. Much bigger footprint in order to provide more strength where the worst of the bellying was.

The bottom half of the original plywood plate compared to the new maple one I made:



Before and after of the top belly pre and post replacing the bridge plate:



I was really nervous that this new, thicker plate would hinder the tone, but it was the exact opposite.

Thoughts?

I've heard of people using carbon fiber in bridge plates, and that sounded like it would be the ultimate, since it's super strong and super light....but doing this job and hearing how much better the guitar sounded with a thicker, larger plate threw me a curveball.

Could it really be as simple as the fact that I used a nice piece of maple to replace a junk piece of plywood, even though the new plate was so much thicker and larger? Or do you think there's more going on there?

For the record, the maple I used was very resonant. I had a couple other boards and the one I used had noticeably more 'ring' to it when I knocked on it compared to the others. Not sure how much of an impact that really had in the end.

[mirwa]

Not to negate your findings, but to offer another perspective.

With the top in as bad of a condition as it was, the restored shape and ability for the top to hold string tension has improved the tone and volume of such an amount that the effect of the additional weight of the bridge plate can not be heard.

Steve

[tahoeguitar]

I tend to agree with Steve on this one. That top had so much distortion and stress in it before you fixed it, plus a solid piece of maple is pretty much always gonna sound better than ply wood. Looking at the "before" pics might lead one to conclude that the top as a system was under-built before the repair, and under-built can sound as bad as overbuilt (in a different way).

I must say that I've played a few '70s Martins with big rosewood bridgeplates that sounded pretty decent despite that. I've also played a number of 70's Martins that did not sound that good.

The top of a guitar is a system, and one component of the system will affect the whole but does not usually stand alone. That's why the answer to the question "Will an Unobtainium Sacredwood bridge make my guitar sound better?" is always "Depends... on a lot of things"

This link on the UMGF has a lot to say on the topic of bridgeplates. http://theunofficialmartinguitarforu...e-bridge-plate

[mirwa]

Originally Posted by Slight Return

Thoughts?

If this was your first go at it, even more impressive, but I think the end result came up extremely well.

Further flattening of the top could be achieved by steaming the surface and clamping it between two plates, but this is a trivial comment on an otherwise good job.

Steve

[Slight Return]

Interesting ideas, thanks for sharing. I hadn't considered that.

@ Mirwa:

I've done *one* bridge plate replacement on one guitar before, but it was years ago and it was my own, and was more for learning purposes than a need for an actual repair. It was a beater and I figured I'd get some practice in case I ever had to do it for someone else.

Lo and behold here I am years later, lol.

Thanks a lot for the support and advice. It means a lot to me especially as I'm trying to take on some more difficult jobs and build my confidence up. I'm still young and want to learn as much as I can.

Anyway: I repaired this guitar once, and it came back. When it first came in, both X braces had come off, along with 2 or 3 spars, and there was a big crack in one of the X braces. And the bridge had lifted off.

The plate had no obviously severe damage. I thought it was okay. I wetted the top out and clamped it down and it seemed to take a set, before I glued the bridge back on.

I have not tried steaming yet, but wetting it out and clamping it flat did seem to help. I had it clamped dry and it did nothing, but leaving it for a week or two under clamping pressure *after* wetting out the area seemed to make a significant improvement.

(I don't have a steaming setup yet. Any recommendations?)

When I was done, it was great. Good action, pretty flat top, good height on the saddle. It sounded good. Not great, but surprisingly good for a cheaper guitar. (It sounded much better with the maple plate I put in after, but it was interesting to have the guitar strung up and playing with the old plate first, and having that to compare to tone and volume-wise)

It ended up coming back 3 weeks later and it was torn up bad again.

My heart sank when I was picking up some guitars and saw that one when I opened the case up. I couldn't believe it was back where it was. I thought I messed up and that my repair failed. I have not felt that bad about any guitar work I've done in a long time and it was extremely discouraging.

What I noticed was my repair didn't fail; the braces were still glued down. The crack hadn't re-opened. All the spars were glued down. You could see an imprint around the X braces on the top bulge.

That gave me some wind back in my sails, and I decided the real problem was the bridge plate was too weak. The whole bulge was around the plate; it wasn't coming up around the X braces anymore since I fixed those.

It didn't have any extensive or obvious damage and I don't know if there was any way I could've known that the plate was a problem too, although in the future, on ANY job this bad, I'll probably at LEAST do a patch on the bridge plate, just by default.

(Do you think that's a good idea? I feel like a patch would be good insurance on severely damaged tops, and might prevent the need for replacing the entire plate)

I really considered doing a simple patch over it, but then I decided that I did NOT want this thing coming back again, and that the most permanent solution would be to replace the bridge plate with hard maple that was:

1) Wider
2) Longer
3) Thicker
4) Grain parallel to the strings for added stiffness and strength

I ordered an 1/8" board of maple from Ocooch Hardwoods online and was very impressed with the maple. I decided to not sand the plate down at all and left it as it came, which was .135".

After painstakingly making the plate template (the original plate was not shaped properly and it was quite an effort making a plate that butted up against the braces without overhanging anywhere)...

...I made two cauls for clamping:



I might've gone a little overboard with the clamps. But I wanted to be *absolutely* sure that the plate was clamped down as much as possible. And it was a very big plate so it had a lot of area to cover. I also wanted to feel like I didn't waste money on those couple 7" soundhole clamps I got

I had this in my makeshift Go-Bar deck for good measure (I attached my Go-Bar deck to my main workbench with some hinges, so I can disassemble it easily and swing it out and set it up as needed)



I also figured by clamping the plate in there as flat as possible, when the glue set up it would "lock" the top in that position. And it did. The action and everything was even better the second time I did this repair, and over a month later and apparently it has not moved at all, which is a huge relief to me.

I've been doing a lot of other work for a while now, and am very confident in a lot of other guitar work, but repairs like this are new to me. Having that guitar come back scared the hell out of me and was a major blow to my confidence until I realized that my initial repair didn't fail; I just didn't see what the entire problem was the first time around.

So I did have it strung up without the new plate initially, the first time around. And it sounded pretty good but not great.

When it came back and I put the new plate in it sounded better. So in a way that was an interesting opportunity.

Thanks again for the replies, too. Always a lot to think about and ways to improve. I really appreciate it.

P.S. No criticism is ever trivial to me, and I appreciate it. I want to get as good as I can and the more criticism and advice I can get the better. Would the steaming have been before the new bridge plate being glued on, or afterwards, to flatten the top out even more? Do you have to use those Thompson bridge clamp things or can you make your own cauls and use basic soundhole clamps?

[mirwa]

Steaming can be done with a small coffee machine, i do steaming of some form almost everyday so have a commercial floor steamer that I modified

Steve