Advice wanted for Harmony Sovereign restoral

[Frank Capo]

Hello. I acquired a project guitar that has suprisingly good tone and playability as-is, but still would like opinions regarding possible improvements. The Harmony Sovereign (see pix - will post better ones) appears to be late 40's early 50's, with laminated mahogany sides and back (despite reading numerous posts that the Sovereign was solid mahog) and a very interesting spruce top - hopefully you can see the grain and advise. It is lacquer finished with a nice gibson-like neck ( reset by previous owner and now has very good action even with lifting bridge), ladder braced, and is very loud, and resonant - notes ring on, with excellent highs though the point needing improvement is a somewhat weak hollow-ish bass. Sounds best played with thin pick

My questions, admittedly sophomoric, are -

Is there any bass benefit in enlarging the soundhole? (you will note that the sound hole is smallish at 3.5in).

I have not looked at the bridgeplate, but wondering if that could be changed to improve tone/bass?

and lastly since I do not think I am skilled enough to X rebrace this, are there any modifications that can be done to ladder bracing to tweak the tone? Thanks.

[Tim Mace]

If you're pleased w/the overall performance of it leave well enough alone as these were some great axes.Maybe
try larger dia. bass strings. One of my favorite body styles. If it ain't bwoke.......don't bwoke it.

[Frank Capo]

Tim, Yes I agree. I need to try out some different strings. The guitar has a piano-ish tone on the bass strings, not unlike the tone of a loud archtop. The top appears to totally flat at this time, and though I have not measured, it may be uniformly thicker than most spruce tops. I assume it could take the tension of larger strings though have not inspected teh bridge plate or whatever its called on a ladder braced guitar. I still wonder what, if any, positive tonal impact a larger soundhole would yield. Cosmetically it would be an improvement. But

[Frank Capo]

Added: The top is unfinished and has no pickguard.

[Tim Mace]

I could be wrong but you may actually lose more bass by enlarging the hole....better get more feedback
about it.

[Frank Capo]

Roger on that. Yes I have heard opininons on that go either way. Most guitars of that size have 4" hole. Perhaps it is the tight waist on the guitar that impacts the bass response, but probably other factors are involved.

I have other ladder braced guitars (30's Kalamazoo L00 types) and they seem to be weakish on the bass also. I guess first thing i'll do is install bone nut and saddle and reglue the bridge, and inspect the contact area at the bridgeplate. Thanks.

[Blue in VT]

Fred,

Harmony Sovereigns are some of my favorite guitars and you have a fairly early model...the later body style was a true OM size...yours is one of the earlier Small jumbo shape...very cool! Your has obviously had some work done on it already...the finish has been removed and that bridge is not original...these all had classical style pinless bridges. So checking out the bridge plate would be an important step...as they were not intended to protect against the ravages of ball end strings the bridge plate was sometimes made of a softer wood. This may need reinforcement so the ball ends don't chew their way through it. I would also get some kind of finish on the top to protect the wood. I'm sorry that I can't really help with your questions about sound hole size or bracing mods...I'm a blues player and the ladder brace tone is what I want.

I'm wondering why you think the back and sides are laminated? In my experience these were all solid wood guitars right up through the early 70's when quality really went into the crapper. In fact most of the Sovereigns that I have seen have a ONE piece back!!! something that is unheard of today....they must have come from some impressive trees!

Cheers...keep us up to date on your progress with this baby!

Blue

[John Cadd]

Larger hole raises air resonance.Smaller hole (partly covered ) lowers air resonance.
To see what a larger hole would sound like put a lump of foam rubber inside the guitar.
Savart worked all that out working on violins . Apart from the foam rubber bit that is.

[David Payne]

I agree on the sound hole question and for what it is worth:

Classical guitars have a smaller sound hole just for the reason of boosting bass. Acoustic guitars are mostly Helmholtz resonators at mid and low tones with surface vibrations dominating the higher frequencies. Helmholtz worked out the math in the 1850's for cavity resonances and it is counter-intuitive but true.... the smaller the hole (in relation to the box volume) the lower the natural note. Think about the low note that can be acheived by blowing across a relatively small (old fashioned) Coke bottle. I know this dates me.....

If you want to test the natural Helmholtz resonance of your guitar carefully blow air over the sound hole with an air compressor nozzle (low and parallel to the top). Some guitars will just roar at their natural resonance. If you get the angle and pressure just right you will be amazed. Guitars with stiff or over-braced tops will resist this test.

I think big dreads and jumbos often have rather large sound holes because they can be quite boomy due to their cavity volume.

Dave

[Rick Homan]

I am about at the same stage as you, Fred: learning from those who know. For a scientific explanation go to Alan Carruth's page on acoustics, and read the two articles. I think this will explain everything you want to know, theoretically.

But, as Alan himself has said, "In theory, practice and theory are the same; but, in practice, they are not." What I THINK all this means for your project is that changing the size of the sound hole will change the pitch at which those lows resonate, but not necessarily the amount of resonance. However, if you want to experiment with letting more air in and out of the box, you might consider a sound port (see Alan's second article).

I THINK producing more bass would involve tapering the braces more toward the edges of the top. I say this because I heard Ervin Somogyi say, in a lecture, that bass is produced by the top moving up and down as a whole, like a piston.

Please remember, I am passing along things I have read and heard, and not speaking from experience. I look forward to reading results of your experiment.

[Ned Knepp]

Rick,
I've known a couple of people that say they "corrected" the balance of their guitar by reworking the bracing. My personal opinion is that this is something for a Pro and I can't work up the courage to try this on my own, not on something I care about.

Ned

[Rick Homan]

I am with you there, Ned. Only Fred can decide whether this is one on which to experiment.

[Frank Capo]

Thanks for all of the comments and advice. Let me try to address some of the points:

1. Interesting that the bridge may not be original...It looks like the previous owner removed the finish around the now liffting bridge. I have not unstrung it since getting it a few weeks ago so time is now to look inside. The bridge was one of the itms i used to date the instrument..

2. the neck was reset the old teeter way...fingerboard sawed off at the tab... the tab needs to be elevated with a mahogany shim, and the binding needt to be fixed.

3. I can see at the heel area where the side was sanded as part of the butchery, i mean reset
process, that it appears to be a 3 layer laminate.


4. It does seem to make sense that shaving the braces - or a certain brace- will allow longer throw, which implies bass...
Thanks. I need to think about what has been osuggested.