The Mystery of Doubleback Guitars

Construction and repair of Classical Guitar and related instruments
Allan

The Mystery of Doubleback Guitars

Post by Allan » Tue May 13, 2008 2:01 am

I did a lot of searching on Delcamp and elsewhere on this subject and was surprised to find there was little or no information, even anecdotal, available on this subject. Can anyone comment on their experience with a doubleback guitar (a Contreras, GVRubio or whatever)? Do you think the doubleback has a significant effect on the guitar's tone (specifically, does the interior cedar lining actually impart any more warmth to the sound?), and is there any actual increase in volume/projection? Has anyone been able to compare firsthand the same model guitar by the same luthier, one standard and one with doubleback construction?

Thanks for sharing any insights you may have on this---

Allan

Marcus Dominelli
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Re: The Mystery of Doubleback Guitars

Post by Marcus Dominelli » Tue May 13, 2008 3:33 am

By "Double-Back" are you referring to the practice of laminating a softwood like cypress to rosewood?
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Re: The Mystery of Doubleback Guitars

Post by dogmatic » Tue May 13, 2008 9:47 am

I 've played two 'double-back' Contreras and several of his standard guitars. I would say the 'double-back' is definately louder but I did not think there was much difference in tone.
Only the difference you would expect from different guitars.

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Michael.N.
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Re: The Mystery of Doubleback Guitars

Post by Michael.N. » Tue May 13, 2008 11:21 am

I've done it on Romantic Lacote copies largely because it's a feature that he used. Perhaps one of the reasons he laminated was to try and increase the volume of his guitars. I've also made a Lacote copy without the lamination but I've never had the two types side by side to compare them. It is something I've been meaning to try on a modern Classical but I have my doubts that it will actually increase volume, it might be very, very marginal at best although I must admit that I'm guessing.
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jrannik

Re: The Mystery of Doubleback Guitars

Post by jrannik » Tue May 13, 2008 1:02 pm

What exactly is the process involved in producing a laminated back guitar? I understood Contreras' double back (doble tapa) guitars to refer to an additional piece of wood that is "covering" the inside of the back. So in reality, the back (not the top) is doubled-up, with the rosewood exterior and tone-wood interior. Is that the same thing as a laminated back?

I haven't played one, but from all accounts they project very well indeed.

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Michael.N.
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Re: The Mystery of Doubleback Guitars

Post by Michael.N. » Tue May 13, 2008 1:44 pm

I've not examined a Contreras 'double top' but my understanding is that the back is lined with another piece of Cedar - in other words it's laminated. If that is the case then we will firmly have to remove the credit given to Contreras for this innovation and rightfully place it into the hands of Lacote - or some other guitar maker pre 1830.
Here's a link courtesy of Brian Cohen. Scroll to the last picture and the 'double top' lining can be clearly seen through the soundhole:
http://www.soundpost.co.uk/Lacguitar.html
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Waddy Thomson
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Re: The Mystery of Doubleback Guitars

Post by Waddy Thomson » Tue May 13, 2008 2:14 pm

In a double back guitar, isn't there a spacer between the hardwood back and the active back? My perception, and I have been wrong once before :mrgreen: , was that an active back panel gives more projection and arguably more bass, if tuned right with the top. The body of the player does not, then, damp the back vibrations. There are also laminated backs, i.e., Smallman, Schramm, which are laminated into a dish to give doming and increase stiffness, which, in some lattice designs, is desirable.
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Michael.N.
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Re: The Mystery of Doubleback Guitars

Post by Michael.N. » Tue May 13, 2008 2:35 pm

In that case the accolades go to Selmer who did a similar thing on some of their D hole guitars.
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Allan

Re: The Mystery of Doubleback Guitars

Post by Allan » Tue May 13, 2008 3:45 pm

For example, I find it confusing when I notice on the luthier Hippner's site that he offers this option as: "Double thickness sides or cedar lined" and goes on to describe this as "Adds extra stability to the guitar, perhaps giving it extended longevity. Some feel the added stiffness helps to transfer more vibration energy to the soundboard, resulting in more response and volume."

I just find it interesting that the luthier doesn't make a judgement based on his own experience, but simply says, "perhaps" and "some feel . . ." This seems pretty vague to me and doesn't do much in my mind to justify the upgrade.

On the Rubio site nothing is explained regarding the doublebacks, however the price increases by about $2,000 for a doubleback Torres or Hauser versus the standard Torres or Hauser. I really have no issues with the price or the time and effort it must take to construct a guitar this way. My question is, simply, does it work or not? The implication is greater volume/projection and better tone, but pending further enlightenment there seems to be a lack of credible evidence either way.

Would you spend another $2,000 to upgrade your guitar choice to a doubleback model?

Allan

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Waddy Thomson
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Re: The Mystery of Doubleback Guitars

Post by Waddy Thomson » Tue May 13, 2008 3:54 pm

I think, the reason for being vague is that it is very subjective as to whether or not one is really better than another. It will definitely change the tone, and probably projection, but whether it is better, is in the ear and the mind of the player or listener, not the maker. Also, it is pretty impossible to build two comparative examples that are close enough in similarities to make the comparison. No matter if you build them exactly the same, except for the double back, or laminated sides, or whatever, just the variation in the wood can be attributed to the difference in sound. In steel string guitars, very stiff sides seem to add stability to the guitar, and give greater volume from the top. I don't know if it is as true in classical guitars as it is in steel strings, as the level of tension is so different.
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Derry

Re: The Mystery of Doubleback Guitars

Post by Derry » Tue May 13, 2008 4:17 pm

I have a GVRubio douple back as well as the GVRubio arch top,, both have spruce sound boards,,

the double back is BR sides and back with a very fine grane cedar lining inside the back,, the arch top is ribbon maple sides and back,,

the double back is louder than the arch top and each gutar has its own personality,, they both have great sustain and a very even tone throughout the fretboard,, the arch top does offer a crisper slightly sharper sound than the double back which is due to the maple sides and back,,

they both project very well,, I have stood 30 feet in front of each being played and you can notice the bouble back being just a tad louder but still not deterring any of its fine quality of music abilities,,

I play Genus GR45s on both instruments,, high tension on the trebs and med on the bass,,

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James Lister
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Re: The Mystery of Doubleback Guitars

Post by James Lister » Tue May 13, 2008 4:27 pm

The problem is that any changes to the back and sides tend to have a relatively small effect on tone and volume (compared to changes to the top), so it's always difficult to say anything definite about the effects of such changes. Hence phrases such as "perhaps" and "some feel . . ." which is frankly more honest than saying anything more conclusive.
Having said that, I don't think there's much debate that making the back (and sides) heavier and stiffer will result in more of the string energy being transferred to the top. The question is, does this make a significant difference to volume, and does it affect the tone?
This is Smallman's approach, of course, making not only the back and sides very stiff and heavy, but also much of the top - with just the lower bout of the top being very thin and light. This combination of very light (lower bout) top and bridge, and very heavy everything else, is what gives Smallman's (and similar designs) their volume, rather than the lattice itself, which is simply a means to the end of producing a really light top. At this extreme, most would agree that volume is increased, and that tone is affected (for better or worse), but again, I would say that the top has the far greater role in these changes than the back and sides.

There is also much confusion, as different makers use different terms to describe the same things, and the same terms to describe different things (we like to keep the punters guessing :wink: ). So a double top guitar may be a composite top, or may have a second top somewhere between the top and the back. This may also be called a double back, which could also be a laminated back. Confused?

James
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senunkan
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Re: The Mystery of Doubleback Guitars

Post by senunkan » Tue May 13, 2008 5:22 pm

I think the Conteras double back is an addtional sound board just before the back piece.
It is not referring to a laminated back.
Our delcamp luthier Patrick Mailloux (patmguitars) has a description on his website.
http://www.patmaillouxluthier.com/nouveaut_en.html
I hope he can chime in to give us a better view of the double back.
James is right in the sense that the terms double top or double back is quite confusing.
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Waddy Thomson
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Re: The Mystery of Doubleback Guitars

Post by Waddy Thomson » Tue May 13, 2008 6:46 pm

That is the way it was described to me, by, I can't recall who!
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jrannik

Re: The Mystery of Doubleback Guitars

Post by jrannik » Tue May 13, 2008 9:10 pm

Allan wrote:"Double thickness sides or cedar lined" and goes on to describe this as "Adds extra stability to the guitar, perhaps giving it extended longevity. Some feel the added stiffness helps to transfer more vibration energy to the soundboard, resulting in more response and volume."
I agree with Allan, it's strange for someone who's speaking of their own work not to endorse its effectiveness more heartily (i.e. that he wouldn't say "The added stiffness does transfer more vibration energy"). That would cast doubt in my mind about the benefits of the technique for sure.
Michael.N. wrote:I've not examined a Contreras 'double top' but my understanding is that
the back is lined with another piece of Cedar - in other words it's
laminated.
Thanks for explaining! I imagine I'll continue to display my lack of woodworking terminology and guitar building knowledge, so I appreciate having these points explained to me when I fumble around with my own explanations!

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