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]

stainless steel?corian?

[hobocaster]

regarding the soundhole size..

i am lucky to own a gibson L-1 flat top circa 1929. it has been thrashed over the years by some heavy hitting players and numerous repairs, but is currently in good repaired playing shape. the first thing people notice when they play it is the wonderful bass- it's loud, and deep, and just plain sounds good. it really seems to resonate from some ghostly depth inside the guitar. at some point before i owned it (possibly 75 years ago, possibly 10 years ago.. i just have no way of knowing) someone reduced the size of the soundhole by gluing in an extra "donut" of wood, the same thickness as the top, in the existing hole. i have no idea why. whether that is a factor in the incredible bass of the guitar.. i dunno. i just wanted to throw out an example to consider. (i'm not advocating shrinking your soundhole)

i agree with whoever suggested the bridge is not original. i've seen many of those guitars (and love 'em) but none with that style bridge.

cheers

[Ned Knepp]

Fred,
I think maple might prove to be a little better than Masonite. Hard enough to handle the ball end strings, strong enough to reinforce the bridge and top and light enough to keep thing moving.

Ned

[Frank Capo]

Just kidding about the masonite...Probably will go with maple, but considering the guitar was "piano-y" sounding with the original spruce bridgeplate, maybe something other than maple will tone it down...anyone use mahogany for bridgeplate?

re soundhole...later sovereigns do have a larger (4") soundhole... I have to admit that if I thought I could cut a larger soundhole without botching it, I probably would...

[David Payne]

Fred,

You would only want to enlarge the sound hole if the bass notes are too strong and boomy. I worked as an engineer designing noise suppression resonators. I have also done some vibration testing on guitar bodies to demonstrate similar principles. The smaller the sound hole in relation to the volume of the box the more bass. I don't know if you saw my post back on page 1 about Helmholtz resonance but it is kind of counter-intuitive.

I have had good luck with guitars that had poor low end by using John Pearse bronze mediums (if the guitar can handle heavier strings). Strings can make a big difference sometimes. Maybe beef up the lower strings by mixing sets of strings you have had good luck with in the past.

Mahogany is a little soft (generally) for a steel string bridge plate imho. That's why you see various maple and rosewood generally used. Bridge plates made of 1/4 sawn hard maple are kind of the default material (usually .100" thick), again imho.

Since the movement of the top enhances low end by acting like an air pump and surface vibrations (more rigid parts of the guitar) enhance higher frequencies, my suspicion would be that the bracing pattern used, the stiffness of the bracing or the thickness/stiffness of the soundboard as a system is well, too stiff and can't move to make the low notes. This would also enhance the higher register (if that is what you mean by piano-y).

When it is strung to concert pitch is the sound board bellying upwards in front of the bridge and lowering slightly behind the bridge? If the top is very flat at tension I would wonder about it's possibly being too stiff. Just some ideas to think about......

Best wishes,

Dave

[Frank Capo]

Dave,

Thanks again for your valuable comments. My soundhole dilemma is more based on asthetics (I think 4" hole is more visually appealing), precedence (most flattop guitars have 4" soundhole) and provenance (maybe if I enlarge the hole I will miraculosly play like Clarence White).... But I understand the technical aspects of your comments.
I probably wont enlarge it.

Since the guitar also seemed to lack overtones and coloration, maybe i'll try a rosewood bridgeplate...

The guitar appears to be quite stiffly braced. There is no top-belly. The braces are large and well attached to the top. If I was to attempt to scallop a brace, which one of the rungs would you suggest - and what acoustic damage coul dI do if over-carved?
thanks

[Tim Mace]

might as well use it for kindlin'...or fry up some scallops

[David Payne]

Fred,

I agree with others that doing this in steps one change at a time is best. See what it sounds like after the bridge plate is replace and then proceed if you want to. I also like the blues sound of the early guitars and I see the point in leaving as is. I have a small body Martin that gives me that sound now that I love.

As you know, normally carving braces is done with the top off. I don't know if your plan was to remove the top or work from inside as best as you can. With the top off, you can feel the rigidity by using your hands and you can tap the wood to see if it is beginning to move musically in the low tones. Removing and reinstalling the top is no fun.

I know people have ladder braced guitars out there that sound wonderful. However, the nature of ladder bracing is that the stiffest elements run in the long direction and the cross elements stiffen the short dimension as well. It's just my opinion but where can the soundboard move at low frequencies? Having said that, if the bracing was light enough to move but still strong enough that the guitar doesn't fail, it would probably improve, but this is a difficult balance.

If you are going to be carving inside the guitar the best you can do is make changes very slowly and then string it up and play it a while and work your way to the point at which you get better sound. Knowing when to stop is the hard part. I guess the worst case is you go too far and have to remove the top anyway.

It also depends on your goals: Do you want to preserve the instrument in as close a manner as historically original? Or, do you want to play it and optimize the sound?

If you want to make the tones a lot better, Re-bracing with the Martin style X pattern would be ideal. Martin's "X" bracing was genius and I think there was a reason almost everyone copied it. Today, other than a few lattice, double top and composite materials folks, most people are still copying it.

Sorry about the long posts, I am a little nuts about detail (and maybe from lacquer fumes).

Dave

[Frank Capo]

I appreciate the post. Again, as acquired it is beyond preservation, so my task here is to restore the instrument that was somewhat abused by previous owner, and make incidental improvements. Not looking for holy grail here but this does have potential. I will not disassemble the guitar - so rebracing is not in the picture. I have a finger plane, that i used to remove remnants of the spruce bridgeplate, that could be used to scallop one of the braces if needed. Since the top was previously unfinished/sanded, I will sand it some more to freshen the surface before spraying. Any material removal will help since it is a very thick stiff top. I will have the bridgeplate and other minor repairs done in a week or so and will report. Thanks.

[Ned Knepp]

Fred,
I could be wrong but it seems to me that removing material from the face (aka sanding) would be a lot like scalloping braces. It could be that you need to sand and finish the top before starting in on removing brace material. It's just a thought.

Ned