MIMF

I saw an article about the Guild 12 strings guitar, that Page, May, Vaughan and a lot of heavyweight players preferred them and that they are one of the best 12 strings made.

Does anybody has experience with them?
What would be the major design aspects that made them a really good guitar?
Is there any difference on tha bracings?

Thanks a lot

I once worked on an extensive repair of one with my partner at the time. It had been re-conditioned at the factory and the owner took it with him when he went to work on a Vista project out west. A drunk broke into his tent and took the guitar. He held the head and dragged it along a dirt road for about a mile. There were small stones embedded in the top, most of the bracing on the top and back was loose, the head had cracked, and there were lots of top, side, and back, cracks. We got it back together and working well, but we never could get all the 'freckles' out of the top.

The design was pretty 'normal', there was just a lot of wood. The top was thick, with wide and tall bracing, and, as I remember, an extra 'tone bar'. Everything was well balanced, as evidenced by the good tone, but it used all the energy of those 12 strings to get a sound that was not especially powerful, again, if memory serves. Playing amplified rendered the lack of power moot, and the sturdy construction allowed for playing as hard as you wanted, and could take a reasonable amount of abuse. What that one got was 'way out of the 'reasonable' class, and it was notable that it was repairable at all.

Back in the Navy I got one of the Eko 12-strings they made in Naples (for $35!). It was even more over built. The neck block was laminated maple 'pin block' stock, and filled all the space between the rim and the upper transverse brace. The rim was bent from a single piece of maple. The bridge was glued to the top and through bolted to an aluminum plate on the inside. If anything it was even more heavily braced than the Guild. Again, it had decent tone, what there was of it...

You don't need to go to that extreme, unless you really plan on using it for street fighting.

Some years back I read that what matters in a guitar top is not strength, but stiffness. Any top that is stiff enough to hold up under string torque over the long term will be strong enough. Since stiffness goes as the cube of the thickness of the top or the height of the bracing, you don't need to make the top twice as thick to handle twice the tension. For twice the tension all you really need to do is make the top about 25% thicker, and the bracing 25% taller. You'll need a bigger bridge and bridge plate, of course, and it makes sense to make the bracing wider to get more glue area, just in case, but the top does not have to be twice as heavy.

Of course, a 12 string set doesn't really pull twice the tension of a six. According to the D'Addario catalog their EJ36 'light' 12-string set (which is what most folks use) totals out at 248# of tension. A set of EJ16 'Lights' for a six string carries 163#, a 'Medium' EJ17 set is 189# and the EJ18 'Heavies' pull 216#. The 'light' 12-string set pulls about 30% more tension than a set of 'mediums' for a six, and only 50% more than the six-string 'lights'.

For the first 12 I made after realizing that I went on the heavy side anyway, adding 25% to the thickness of the top and the height of the bracing, and so on. I used the same brace pattern as I usually do. The top ended up weighing 290 grams, and the bridge was 35 grams (plus whatever for the saddle and pins). A similar six sting made a little while before had a top that weighed 258 grams, and the bridge was most likely in the range of 25 grams (I don't always keep as good records as I should!). So the 12 string top + bridge was about 325 grams, while the six was 283. The strings on the 12 were driving about 14% more weight, with 30% more tension.

That is one loud guitar. It was the first one I ever made that I could not sing over. That was about 15 years ago, and I've had no complaints. I did see the customer a few years after I built it at a show, and he was very happy with it. His wife said that it was 'loud', but didn't seem to mind.

FWIW

Thank you very much for the info, it's really detailed and knowledgeable.

That extra tone bar is on that couple behind the bridge?
How do you find it? Never heard of it.

But I'm pretty much saving this posts for posterity

I can't help much about the construction details, but I have owned a Guild 12-string for probably 40+ years, and it has held up great. Still like new! Back in the day they were really well regarded.

Most steel strings have two more or less parallel 'tone bars' below the X braces in the lower bout. Guild used three.

Taylor also uses three tone bars on their 12 strings.

I built this 000 12 string about 15 years ago with advice from Alan Carruth and others. Cedar top was 10 thou or so thicker than a 6 string and braces a little wider and taller as well. Cedar top and mahogany back and sides. Still doing well and sounds great according to my sister!

Nice one! Stick to the double tone bars?

000 bracing with nothing other than a little wider and taller.