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Re: Offset hole - brace question

Posted: Tue Jul 31, 2012 11:03 am
by Ken Hundley
I have removed the sound hole from the top completely for a number of reasons, none of them truly scientific, I must admit, mostly theory, some aesthetic.

First, I thought of the soundboard as the surface of the drum. Being the primary emitter of sound in a guitar, it seemed to me that, though it was traditional, a sound hole removed a decent percentage of the emitting surface. Moving the hole off of the soundboard increases the available emitting surface area.

I think holes are necessary for a couple of reasons. One was mentioned above....access to the bridge, braces, and neck bolts if built using that style as well. Second, the guitar needs to breathe to fully realize the vibratory potential. The top is vibrating "in" and "out", so to speak. If we eliminate the sound hole altogether, or don't configure it properly regardless of its location, my theory was that you are creating alternating positive and negative pressures in the guitar. By nature, positive or negative pressure inside the guitar soundbox reduces the energy being emitted, as the energy used in vibration must overcome the pressure inside the guitar to create enough movement to emit sound. I think this is where the sound port also has some benefit, by allowing further ingress and egress of air throughout the vibrating cycle, both equalizing the pressure on both sides of the soundboard, and allowing more of the energy being used to be converted to sound. By removing the sound hole from the top and placing it where most will add a soundport, I had to come up with another location for the sound port to realize the same benefit.

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The interesting effect I have noted on my designs is that even the smaller bodied instruments have a deep, breathy sound to them with the bass, an effect I find very difficult to describe accurately. Every player that has tried one of them is astonished by the sound coming from the guitar, both as a player and a listener.

I am still working on the bracing....I am not quite convinced the "benefits" I have noted from laminated bracing are worth the extra effort required to make them. I will try a guitar with the same bracing patterns I have come up with, but with solid sitka bracing, and see how it compares. There is a certain distinctive flavor to the sound on all the instruments I have made with laminated bracing that effects primarily the midrange, I would like to see how this changes, and whether it is a result of the bracing pattern or the laminated braces. I have a wenge/sitka and a zebra/sitka guitar in process right now with those thoughts in mind.

Other than that, I thought the laminated braces and off-sound hole just looked pretty frickin cool, and was tickled pink that it came out sounding good too.

Re: Offset hole - brace question

Posted: Tue Jul 31, 2012 11:33 am
by ken cierp
Two thoughts

"Acoustic Supension" HiFi speakers do not have a port and in fact the enclosure is filled with damping material, on the other hand "Bass Reflex" designed speakers have no filling and indeed the enclosures have a "tuned" port --- go figure??

and Ken H. ---how in the heck have you or are you going to glue on the bridge?

Re: Offset hole - brace question

Posted: Tue Jul 31, 2012 11:41 am
by John Parchem
kencierp wrote:… and Ken H. ---how in the heck have you or are you going to glue on the bridge?
Must be a trick question as Ken's clamp does not need sound hole access.

I do get some of the issues, With my large hands it has been a struggle for me to work through the ukulele sound hole.

Re: Offset hole - brace question

Posted: Tue Jul 31, 2012 11:55 am
by Dave Bagwill
I wonder if Bose would have a comment on a guitar box? I'm gonna send them a letter!

Re: Offset hole - brace question

Posted: Tue Jul 31, 2012 12:06 pm
by ken cierp
Hey Dave --- I see "Fender" is getting into the HiFi biz, I think they supply VW with sound systems?

Not a trick question --- I don't think I could get my hand far enough in to reach the SS Bridge clamp wing nuts -- but maybe?

Re: Offset hole - brace question

Posted: Tue Jul 31, 2012 1:14 pm
by John Parchem
yup, forgot about tightening down the wing nut inside.

Re: Offset hole - brace question

Posted: Tue Jul 31, 2012 1:30 pm
by Ken Hundley
kencierp wrote:Two thoughts

"Acoustic Supension" HiFi speakers do not have a port and in fact the enclosure is filled with damping material, on the other hand "Bass Reflex" designed speakers have no filling and indeed the enclosures have a "tuned" port --- go figure??

and Ken H. ---how in the heck have you or are you going to glue on the bridge?

I never took pictures of that process on these designs, did I? Your bridge clamp (when using standard bridges), or an adapted version to fit my odd bridge shape when using mine. I made a bridgeclamp like yours with a larger foot print, imbed it in Friendly Plastic which gets molded around the bridge. I mount it the same way as yours....through bridge pin holes. I have two screws clamping down from the outside edges to keep the radius true as well, though they are a little staggered to get more of the meat on the bass side of my bridge. I'll have to shoot pics next time I do it.

The key is to make sure my sound hole is big enough to get my arm that far back.....was a challenge on the first one. I had bruises for a couple of weeks after trying to tighten or loosen those screws.