Official Luthiers Forum!

Has anyone here messed with this? Got a couple cheap acoustics I've been thinking of practicing on. Not sure what kind of tool I would use either.


Sent from my iPad using Tapatalk

_________________
"I'm not going to say that perfection has never been achieved. However, if it has, it probably went unnoticed due to it's lack of character."

Sure. I've done it to my builds on occasion and other guitars. Use a small plane and work deliberately. Helps to have skinny arms. Good luck.

_________________
Aaron Craig

Like a finger plane? What do you mean by "work deliberately"?



Sent from my iPad using Tapatalk

_________________
"I'm not going to say that perfection has never been achieved. However, if it has, it probably went unnoticed due to it's lack of character."

Yes, a small finger plane or a plane in the style of Mr. Boone's brace carving plane will work just fine. By work deliberately, I mean work carefully, slowly, and, in general, don't take off large amounts of material without thinking about how it will affect structural integrity.

_________________
Aaron Craig

I only tinker with the voicing on a guitar that already has a good sound, but not as good as it should have considering its design and woods. Also, I want to have on hand a guitar of the same size, type, design and wood densities. The first law of revoicing says " Don't get greedy, you can only improve a guitar up to what others have achieved with a similar design and woods."
I compare two things between the pattern guitar and the guitar being tinkered with. (1) The note the wood makes when thumped with the thumb, especially at the bridge but also moving the thumb all around the top. When I do this thumping I often cover the soundhole with a piece of carboard so I am not distracted by: (2) The note of the tuned air inside the guitar when excited by blowing a puff of air at the soundhole like playing a flute. This takes a huge burst of air and practice, but you can learn to identify the pitch of the note. Sometimes I wrap the body (except the hole) with a towel to damp the wood resonance.
The two resonances are always at pitches in the very low range of the guitar or a little lower (sometimes lots lower in a booming dreadnaught). If the two pitches are close to each other or tuned a perfect fifth or perfect fourth apart, it can cause a chromatic scale in the bottom octave to have annoying loud and quiet zones.
To make the subject guitar sound more like the pattern guitar, copy its resonances. To lower the wood resonance, remove tiny slivers of wood from the braces in the parts of the top that don't boom like the pattern guitar does right there. In other words, the pattern guitar helps you identify where the subject is overbuilt. To lower the air resonance, make the soundhole smaller. You can experiment with this by taping tiny crescents of thin cardboard on the soundhole edge. Unfortunately, to raise the air resonance you must enlarge the soundhole. All these changes are done with tiny, tiny, tiny adjustments or you will loose any good sound the guitar had in the first place. Don't get Greedy! one- tenth of a gram of wood off a brace will make a big change. If you shave too much the guitar will sound like tinny junk.
Good luck!

Thanks. This guitar is a Martin dread knock off. I've done a significant amount of work to it already. I reset the neck, refretted it, etc. The finish got pretty messed up during that process for reasons completely off of this topic. It does have a "decent" sound to it. It just feels and sounds overbuilt.

Now, if it appeared to be voiced and built for tone rather than stability, I would second guess this idea but it clearly is overbraced judging by it's weight and how stiff it feels. I measured the top and it came in around .130"-.135". I'm planning on refinishing it at some point anyway so my plan is to sand the top a bunch while getting it ready for refin. I figure at that point, I could check it for progress and proceed with brace shaving if necessary.

The test guitar is a great idea. I just finished this other dread and for the life of me, I can't remember what I did to make it sound so good but this thing sounds pretty ridiculous. Same basic materials and construction methods though.

I'm glad to hear so many people say "A little dab 'll do ya" when it come to this process. Sounds like a more immediate change without too much manual effort. My favorite.


Sent from my iPad using Tapatalk

_________________
"I'm not going to say that perfection has never been achieved. However, if it has, it probably went unnoticed due to it's lack of character."

I was just reading a long article on this topic last night. If you have access to issue #47 of American Lutherie or the The big Red Book volume 4, there is pretty in depth article with input from five builders and repairmen. It includes their views on how and when to do it and what tools they use. Quite a few photos too.

_________________
Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

I've done it to about five guitars. Each seemed overbuilt. Every time was a success! one time, I went a little more then I should have. But it still sounds better than before I started. I usually take the scallops down a little more, try to get the tone bars. And maybe take the X down a little. Small plane small chisel or whatever. How much should you take off? I guess you will find out! Lol

What if I take it down too much and it sounds great, but the guitar doesn't last? Well, assuming it's a cheap guitar, let's hope the player writes a song with it that last forever!

_________________
Pat

I tapped around on the guitar a little bit today. The vibrations from the low strings felt pretty even but I wonder how strong they should be. Meaning… I'm wondering if they are just weak overall. It would be much easier if there were some dead spots. I am wondering if the bracing is fine but the top plate is just too thick.

In my last post I talked about a guitar I built that would be suitable for a reference. This guitar is definitely higher in pitch than the one I'd use for reference. On that one I seem to remember thicknessing the top plate to somewhere around .095"-.098". The top was Sitka and who knows what this one is. I assume either Sitka or Red spruce.

The braces on the back are different from the acoustics that I've built. There are 2 tall/skinny ones underneath the sound hole area and then 2 short/fat ones underneath the "prime real estate" area. I mostly see these kind on older Gibsons and Martins that come through the shop. Of the folks here who have done this revoicing in the past, did you only alter the top braces or did you address the back ones as well?


Sent from my iPhone using Tapatalk

_________________
"I'm not going to say that perfection has never been achieved. However, if it has, it probably went unnoticed due to it's lack of character."

Ok... Removed all Polyurethane from top. That helped a little bit. Also sanded the top down a little bit. I don't think I removed much thickness overall. I did remove more over the rims than from the middle. It seems to be more responsive now but it's hard to tell. Also nipped at the X brace and the tone bars. I am thinking about putting the bridge back on and stringing it up to check progress.


Sent from my iPhone using Tapatalk

_________________
"I'm not going to say that perfection has never been achieved. However, if it has, it probably went unnoticed due to it's lack of character."

Thanks for all of the replies.... [SMIRKING FACE]

Since my last post I got inspired by a Caleb Smith D-28 copy that belongs to a friend of mine. We rehearsed on Monday night for some shows this weekend and I tapped around on the top and noticed how responsive it was. I also felt around inside the guitar to see what was going on with the braces.

With the sound of that top in my head and the feel of those braces committed to my finger tip's memory, I went home that night and messed with it some more. I took way more off of those things than I ever thought I would. Certainly more than anyone on this forum would probably advise. The result was stunning. Doesn't even sound like the same guitar. Tons more bottom end, responsiveness and sustain.

The braces were not scalloped from the factory. The top was thick and encapsulated in polyurethane. No wonder it sounded so stiff and dead. It's as if someone at the factory started the voicing process at 4:45pm on a Friday and when the bell rang at 5, they we're like.... "Whatever.... That's good enough" and just threw it in the pile of tops waiting to be attached to rims.

Maybe it'll collapse in a couple years. Who knows? Furthermore, who cares? Even with setups, accessories, etc. throughout the years, I still probably have less than $700 in the thing. Now it sounds amazing. Everyone that hears or plays it says so completely unprompted.

So, all in all, I would say the revoicing project was a success.


Sent from my iPad using Tapatalk

_________________
"I'm not going to say that perfection has never been achieved. However, if it has, it probably went unnoticed due to it's lack of character."

There you go!

_________________
Pat

Great story! Thanks for sharing your risk and success.

_________________
Formerly known as Adaboy.......