Official Luthiers Forum!

I have become interested recently in the making of a Contreras style double top (actually double back) and am very curious about how it is constructed. Information by googling is very sparce, plans, details or even sketches seem non-existant so far. Is it a protected species?

Question that spring to mind are is the second back braced? - radiused (and which way? - how is it supported in the guitar?. - is the void between it and the back isolated completely from the top "chamber" - if so, is the volume between the normal top and the second top around the same as a "normal" classical, - how much space separates the back from the second top? - are the top and the second back coupled, i.e. linked in any way?)

Any information/suggestions for links would be much appreciated.

in advance, thanks

Colin

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Eventually you will get better replies. In the meantime, the Contreras double top was described to me as a back made of cedar or spruce like the top wood, but laminated on the outside with a rosewood veneer to protect it from damage. It was braced like a back. It was a plywood back of the highest quality woods. The theory was, it contributed better to vibration.

As a contrast, there is the Smallman back, which is heavy laminations to make a solid back which avoids detracting from vibrations if you hug the guitar.

At Lmii , check "nomex" in the top wood section

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Francis Richer, Montréal
Les Guitares F&M Guitars

I am actually asking about a different animal - although tops using a nomex sandwich are also called double tops

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Colin, Todd Lunneborg has a build similar to what it sound like you are planning (essentially two tops) over on LuthierCom but you will need to be registered on the forum to access it.
I have almost completed a Grande Bouche Maccaferri build which employs a double back, it totally isolates any possible dampening by the player from the resonating surface. I posted my progress on the ANZLF here (6 pages! so be prepared for a long read! ) which can be accessed without registration and may answer some of your questions regarding bracing and isolation of the chamber, mind you, bare in mind that these are merely my thought processes, Contreras may (or will) have employed completely different methodology . I will say that I am impressed with my results, the volume is noticeably louder and clamping it tighter into your body makes no appreciable difference.

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Nick Oliver

http://www.oliver-guitars.com

Nick,

thanks very much for the reply, it was appreciated.
I have looked at both links - Todd's build is suspended of course, but was informative.
Your build was - - wow!
You will guess I was well impressed! Real attention to detail. It has given me a lot to chew on!
I am struggling with basic builds at the moment, low bling stuff, which has its own appeal, concentrating on fit and (especially) finish.
I look forward to seeing the final result of your build and any soundclips when you can get them done.

Respect and Cheers!
Colin

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Doing more on it now. The suspended version doesn't work, I didn't believe the guys who tried to warn me, so I am now inlaying the back with some stealth sound ports and decoration.

I am, however, doing a laminated (Nomexed) back for my Sonic Sitka project build and the results so far are great. I've been chatting with Paulo (Manuel Contreras JR) on and off and have come up with a couple of tricks to keep things toning like his guitars do. I'm interest to see what will happen with these 2 as a sound "volume comparison." If nothing else they'll be great write offs when tax time comes next year.

His fathers guitars were one side of the coin (more like my build linked above) and Paulo's version is the next evolution, more like my sonic build. It's a tricky beast for sure.

Good Luck.

Todd

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Todd Lunneborg
http://www.tlguitars.com/
http://www.fretboardjournal.com/

Thanks for the post Tod.
It would be nice to know how things go with your builds. Maybe you'll post something about them?
Some really nice looking builds on your site BTW

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.