Jump to content
Sign in to follow this  
Idunno

Double top construction

Recommended Posts

Until now I never had a curiosity about it. Tonight, for reasons unknown, the thought came to me so I looked it up. This particular builder is using honeycomb material I've been using for >>>>>>>>> years in aircraft flight control surfaces and floor boards. Anyway, it's short and informative.

 

http://www.dominelliguitars.com/tech-talk/double-top-construction.html

 

Share this post


Link to post
Share on other sites
Eastman is currently using the same technology. I hadn't heard of anyone else using it until now. I'd like to see Phil review one and get his impressions. (Are you reading this, Phil? ;))

Share this post


Link to post
Share on other sites

Very interesting... do wonder about what might happen over seasons with changing levels of humidity, etc. Thinking of older Ovations and cracked wooden tops perhaps a result of being connected to those plastic bodies. This a tad different with plastic top connected to wood bodies. Do like to see folks try innovative approaches, but good to ask "yeah, but what about...?" I dunno, Idunno

Share this post


Link to post
Share on other sites
Very interesting... do wonder about what might happen over seasons with changing levels of humidity' date=' etc. Thinking of older Ovations and cracked wooden tops perhaps a result of being connected to those plastic bodies. This a tad different with plastic top connected to wood bodies. Do like to see folks try innovative approaches, but good to ask "yeah, but what about...?" I dunno, Idunno[/quote']

 

I had the same question. Garrison guitars were well-regarded until they came apart at the seams due to the differential in how the fiberglass frames and the wood bodies reacted to temperature and humidity. Now, Garrison is just a memory.

Share this post


Link to post
Share on other sites

Good points about differential expansion/contraction properties between unlike materials. If a rigid bonding product is used it could become fatigued and crack along the material boundaries with time and many expansion/contraction periods. Using a more flexible bonding material, like epoxy resin (versus rigid polyurethane or polyester resin) would solve the long term problem. The trade-off is because it's flexible (softer), epoxy will attenuate frequencies more than the more rigid resins. How much? I probably would not be able to hear it.

Share this post


Link to post
Share on other sites

The whole design of the classical guitar underwent a pretty radical transformation 20 or so years ago (I'm not an expert on classicals but I kind of follow the literature). People started rethinking the traditional 5 and 7 fan braces and all of the other traditional designs, driven in part by the desire to make a louder nylon string guitar. Two things happened more or less at the same time, a German builder named Damman started building guitars with tops made of very thin spruce laminated with man made fabrics like kevlar and nomex. As I recall he also used balsa in some of his laminates. These became know as "double tops"

 

The other big innovation was started by an Australian named Smallman who replaced the fan braces of Torres and Hauser with a lattice of interlocking braces. This segued into a whole bunch of different "modern" bracing patterns.

 

I've had an opportunity to hear some guitars built in both schools, as well as traditional fan braced guitars. I am not a good judge of classical guitars, they all sounded pretty darn good to me. You will commonly hear the opinion that both double top and lattice guitars are very loud and project to the back of the hall, but often at the expense of sound quality - "nasal" is a term I hear applied to them.

 

I had an interesting experience last fall. We went to a recital of classical music done by a very good guitarist who has studied guitar music of different periods - Renaissance, Baroque et al. He is also an accomplished builder. After the show I was chatting up to him, I saw that his guitar had a sound port so I asked if he was building in one of the modern schools or Torres. He laughed and said he had tried both kevlar double tops and lattice bracing and he said he could see the appeal for modern players in big concert halls, but he preferred the warmth of traditional fan bracing and had gone back to that in all of his instrument.

 

I am not aware of double tops being widely used for steel strings (I'm sure someone is experimenting with it) but there are a bunch of alternate bracing patterns for steel string guitar - again, what I call the "modern" school of construction. I've heard a bunch of them, played a few, they sound like guitars.

Share this post


Link to post
Share on other sites

I also read about the nasal sound of the double topped guitars and was trying figure out what that cipher meant. All I could think of was a more focused frequency band channeling from the double top but around which range I couldn't guess having not actually heard the sound. I'd read about the use of Kevlar and Balsa wood as well but I did not get an idea of the extent of their uses. I know they are sandwiched between two soundboards but I haven't found if there are voids of airspace in certain areas or the materials completely fill the space between the soundboards. Balsa is a very soft wood and I would think it to be attenuating rather than augmenting. Going with that notion I would think balsa was used sparingly as a separator leaving large areas of airspace between soundboards.

Share this post


Link to post
Share on other sites
I've heard a bunch of them' date=' played a few, they sound like guitars.[/quote']

 

Frankly, have you ever heard an amateur piano player bitching about how a Steinway is so much worse (or better) than a Yamaha? Or a professional piano player owning 50 pianos, just because the one or the other is so much different?

We are all, collectively, guilty of gear addiction and so much that we completely forget that the greatest difference in sound comes not from the instrument, but from the one playing it. Maybe, we are going to hide our own shortcomings behind the perceived shortcomings of the instrument.

Or, in other words, a good player can make the most crap guitar sound good .....

 

Share this post


Link to post
Share on other sites

Hang out on the piano forums for a while. Pretty much the same as the guitar forums, but pianos are too big to collect and harder to do a bunch of A/B comparisons unless you're in a piano store.

Share this post


Link to post
Share on other sites

Hang out at any forum and observe that people choose the people they like but can't say why due to the TOS. So, (LOL) we openly explore it anyway in the subliminal: We see preferences identifying friend or foe at the brand level. Toss in a product, say, a ToneRite in the context of better sound, and watch the melee begin as people obsess the forum/thread/post psyche appropriate to preferences, stances and resolve of the respondents over that product and context. And, none of it is the product that imparts a change. It's just the seasoning. The psyche of any forum from day one to any succeeding day is steered by labels, in both a direct and indirect manner, within a very psychologically suspendable TOS.

Share this post


Link to post
Share on other sites

Tribalism. I haven't seen the Nomex Tribe yet, but I'm sure they're out there.

 

Hard for me to get excited about man-made materials. Wood is part of the attraction. I just added to my Koa stash today. Pure hoarding on my part, but once I hit some threshold, I'll start cranking out ukuleles without saving it for some special occasion.

Share this post


Link to post
Share on other sites
Until now I never had a curiosity about it. Tonight, for reasons unknown, the thought came to me so I looked it up. This particular builder is using honeycomb material I've been using for >>>>>>>>> years in aircraft flight control surfaces and floor boards. Anyway, it's short and informative.

 

http://www.dominelliguitars.com/tech...struction.html

 

If you recall when we met, Tim McKnight had just begun building double-top guitars. You may have played one. Tim also does a "double back" guitar as well which is similar and double-sides which are simply two sides epoxied together. The purpose of the double back is to reduce the muffling effect that occurs when you play with the guitar pressed up against your body. The double sides are purely for structural reasons; they are very resistant to deformation or key cracks.

 

My favorite was an OM double top with cedar on the outside, lutz on the inside with nomex in the middle. The back and sides were wenge, but I don't know if it had a double back. It didn't sound nasal at all. It sounded very similar to my Larrivee OM but with more bottom end.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

×
×
  • Create New...