Official Luthiers Forum!

Hi,

Anyone built an all mahogany acoustic?
I'm after info please, I'm looking to build in 00 size.

The top will be mahogany, do you use spruce bracing or mahogany? And does it need a different approach to the bracing ie lighter or heavier?

Thanks

Sent from my SM-G960F using Tapatalk

When we build or retop mahogany-top instruments, we thin the top to about 90% of what we would use with a decent Euro or stiffer sitka spruce, and use our regular red spruce bracing. For a 00, something like 0.095" seems like a good target for the sort of plain-figured mahogany we would likely use, knowing that a few additional thousandths would be removed in binding and prep for finish.

There are more rational methods advocated for determining final thickness, but it is tough to go too far wrong with using Martin's Style 15/17 thickness numbers. Mr. John Hall may have those current thickness numbers available for production 00-15 instruments, and at least the boss and Mr. Morelli will be up at the Nazareth factory this week, so failing input from Mr. Hall, I will ask them to inquire.

Keep in mind that spruce and South American mahogany are very close in average stiffness, but mahogany is the denser wood. Both stiffness and mass matter for top response, so perhaps take a look through the archives and get a feel for the various methods available to balance top stiffness, mass, and the bracing plan. As mentioned, we use a target number (modified if necessary where the top is either exceptionally stiff or a bit floppy), and do final tuning on the instrument using top compliance (thinning of the top - usually at the edges)...more rational methods will likely require stiffness and mass measurements, acoustic analysis, or both.

Finally - the reason to use a mahogany top is that it does not usually sound like a spruce, redwood, or cedar top...if you want something close to a spruce sound with a darker colored top, consider a shaded top or use of a darker toner.

_________________
For the times they are a changin'

- Bob Dylan

Thank this really helpful

I would prefer to build in spruce but love the colour of mahogany top, would I lose alot of tone with the mahogany top?

Sent from my SM-G960F using Tapatalk

I hear more fundamental and a bit less in the way of complexity from new mahogany instruments, but older mahogany-top instruments seem to continue to settle in and mature for fuller voices that seem well suited for a number of blues and roots styles. Beyond that, I would hope that others comment; my suggestion above was aimed specifically at those looking for a dark-colored top, versus the unique appearance and tone of a mahogany instruments.

On playing in...what passes for wisdom here suggest that new mahogany-topped instruments take longer to find their voice...sometimes, decades longer than spruce-topped instruments. Some very well respected luthiers likely consider that notion nonsense, but I will guess that a lively conversation will ensue anytime the topic of playing in or breaking in comes up.

_________________
For the times they are a changin'

- Bob Dylan

There are a lot of Youtube video comparisons of mahogany topped vs spruce topped guitars, so you can kind of judge for yourself:
https://www.youtube.com/watch?v=-brZyZTXoHQ
Better yet go to a music store and play them.
If you like the color of the mahogany top but the sound of the spruce you could try the gunpowder scorch to color the spruce:
https://www.youtube.com/watch?v=5Jfi0sOawT0

I have built an all mahogany 00 sized guitar and it is one of my favorites. It has a very definite voice and seems better suited for some types of music (roots, blues, old timey stuff) but that is why I built it. I was inspired by some of the Depression era guitars (most notably the Martin 00-17) but there are some modern builders making guitars of this type (SCGC).

Mine is long scale, 12 frets clear, slotted head. The rosette is simple in keeping with the guitars of that era - it is bound in mahogany but you can hardly tell (at least some of the x-17's were not bound). I used 5/16 spruce bracing, moderately scalloped, the top is slightly thicker than I would have done with spruce but I don't remember the exact number. I could check if you would like





Single, double, triple ought.

Very nice

Sent from my SM-G960F using Tapatalk

I don’t think you lose tone, you gain the tone of a mahogany top, which would be the reason to choose it.

When I do, I follow all protocols exactly, using the same deflection numbers as spruce and the same final voicing ideas.

So if you ve been doing deflection and resonance testing you’ll have a good baseline...

I have been disappointed with many of the all mahogany guitars I have tried. However, I made a 000 12 fret with venetian cutaway in African mahogany and I was very pleased with the result. The tone is actually quite rich. The body shape, 12 fret neck, and sound port, likely influence the sound. I used Adirondack and Carpathian spruce bracing. I also, added a subtle shadow burst.

http://www.swiftcreekguitars.com/000-12 ... taway.html

_________________
Steve Sollod (pronounced sorta like "Solid")
www.swiftcreekguitars.com

I built a OO 12 fret all mahogany guitar for my son and I used only one tone bar and one finger brace each side thinking it would sound better right away instead of taking a long time to loosen up. My teacher said that mahogany tops take years to mature but my son's sounded nice right away.

Sent from my iPhone using Tapatalk

There is definitely a mahogany-type of sound. I like it, and have owned a couple. Any description is generalization, and every instrument will be different. But I find mahogany topped guitars sound less bright, and a bit more fundamental (not so many overtones). Maybe less sustain also. It is definitely worthwhile to go to a local shop and play some, compared to similar sized spruce or cedar instruments.

If you are building one then, as the others have said, you want the top to be a bit thinner than you would go for with spruce. Spruce for the braces.

That's a beauty! Thanks for sharing. How did you do the burst? And what was your idea with making the mahogany top it thicker?

Sent from my SM-N960U1 using Tapatalk

_________________
Pat

Thanks Pmaj7. First, I had been offered a 1930's 00-17 but had turned it down. Some years later I played a Santa Cruz mahogany 00 and was totally smitten. Decided to build one. Scaled my 000 plans down to 00 size and started making sawdust.

The top is 0.115 thick at the soundhole. I had heard that mahogany wasn't as stiff as spruce and my last couple were built with fairly stiff (or so I thought) Lutz at 0.095 so I just went up 20 thousands (I used that thickness on a WRC guitar that I just built and I'm happy with it). Frankly I know diddly about stiffness of tops and all of that - it you told me a piece of wood was so many cubits per fortnight I wouldn't have any idea what to do with that data. Yes, I thunk on a piece of wood and wave it around in the air and pretend to be doing something significant, but its just a sham. Blind luck seems to be on my side, all my guitars sound like guitars...

The finish is lacquer - the last thing I wanted was a dipped in glass PRS finish. Brown paste pore fill not too aggressively applied (I figured if the lacquer shrunk back it wouldn't matter. Then when I started shooting the finish I added a drop of brown dye to the cup on my gun and just misted around the edge (shooting outward with the guitar on its back). Added some lacquer to make up the cup, shot the edge again but moved in towards the center an inch or so. More clear diluting the color in the cup, another coat moving in some more. Finally the lacquer in the gun was pretty much clear and I was at the middle. Here is another shot of the finish showing the (non) binding



One more story - shortly after I finished it we attended the GAL conference at Tacoma and I submitted it for the Steel Sting Listening Session. If you know how that works, 30 or 40 builders leave guitars behind the stage where one person tunes them and brings each on to stage. The same player plays the same little ditty on each guitar, then the builder stands up, introduces themself and describes the guitar - materials, building philosophy, yadda yadda.

The guitar the preceded mine was a lovely modern fingerstyle guitar with about every buzzword feature you can think of. The frets were at odd angles, the sound hole wasn't in the middle, it had holes in sides that weren't the same thinkness. The top and braces were something from NASA. You get the general idea.

Mine was played, I stood up and introduced myself and said "my guitar is the antithesis of the one you just heard. It was inspired by those cheap Depression era guitars that I grew up listening to - there is nothing fancy or special about it". I sat down and the woman sitting next to me whispered "I liked yours better"