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Permalink Reply by BUGGY (C) on August 20, 2012 at 9:18pm

Some CBG's used to be made from Cedar from memory.... hopefully you are following my thinking via these links...

sorry if I'm going slightly off but its all related.

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Permalink Reply by BUGGY (C) on August 20, 2012 at 9:29pm

So yes, the more you stop the top resonating with clutter, the faster the resonance decreases over time.

keep the pickups seperate and allow the top to resonate around the pickcups with shadow gaps!?

Now off to make a thin spruce top, mahogany sided, rosewood back CBG, with a bone bridge and brass nut...maple neck

with a small sound hole... and no clutter....Hmmm.... if it works for a Acoustic then why not for a CBG...

 

http://www.google.co.uk/imgres?q=resonance+damping&hl=en&sa...

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Permalink Reply by The Phrygian Kid on August 21, 2012 at 2:39am

I been waiting to see who was switched on enuff to mention sustain/decay. Bravo. Smart little bug :)

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Permalink Reply by Michael Fred Johnson on August 21, 2012 at 12:33am

These two guitars are made from similar materials.The one with the plain simple front has a much louder and richer sound.I can only put this down to the lack of clutter and open box construction with no thru neck

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Permalink Reply by Michael Fred Johnson on August 21, 2012 at 12:34am

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Permalink Reply by BUGGY (C) on August 21, 2012 at 1:06pm

Michael also due to the guitar style bridge kinda has a push me pull me twisting action on the sound board

whilst the other just a downward force, but clutter will eat up resonance. On my Diglydog... I couldnt figure out why the sustain was so long... but Dinglydog told me the pickup is clear of the body with a shadow gap around it allowing the top to resonate away....  so less is more... but nice wood helps..

I have a cheap old acoustic got for £30 but the struts run the trad way diagonal and it has some phosphor bronze on and sounds awsome for a dirt cheapie. In the 60-70's we cheapend everything  and never went back to the correct ways...

 History shows us lots of usefull tips.... but a broom handle and a box and some catgut is where this all started...

they were just pleased to get any sound out of it !!! ....Try a piece of meica top, from an old microwave :>)!!

Thin and strong with a bit of flex but no too much....or a piece of dexian shelf.... anyone tried carbon fibre yet?

I have umpteen different parlour guitars and they all sound different... yet similar shapes similar strings....

don't you just love this stuff.. I find it all facinating experimenting.

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Permalink Reply by Bluesheart on August 21, 2012 at 2:01pm

By the way, that is one righteous mustache the gent on that box is sporting!

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Permalink Reply by BUGGY (C) on August 22, 2012 at 1:27am

http://www.polettipiano.com/Pages/airresengpaul.html

see the bit about resonace frequency and air on guitars:

 below for you.

 

 

Unlike the passive resonators of Helmholtz, which only filtered the sounds coming to his ear, the air resonances of closed-box musical instruments play a much more active role in shaping the sound. Air modes can have a pronounced affect upon how acoustic energy flows through the entire system, causing subtle changes in the volume and sustain of the vibrations induced in the soundboard by the strings, and ultimately, the timbre radiated to our ears. The acoustics of some closed-box musical instruments, such as guitars, lutes, violins, and cellos, have been extensively studied. From these studies we learn that the air resonances do indeed contribute significantly to the overall sound of the instrument. One might think that an enclosed air space would have only one resonant frequency, like a simple Helmholtz resonator, but in reality, the air inside a real musical instrument has many modes of resonance, all occurring simultaneously, all filtering and shaping the final sound we hear. The more the space is divided up into smaller sub-spaces, the more resonant frequencies there are, all interacting with one another to create a complicated and unique mixture.

The major resonances of a Martin guitar, as studied by Rossing et. all (see Fletcher/Rossing, The Physics of Musical Instruments). The top two rows show front and back plate resonances, the lower row the air resonances. Note how many different resonant frequencies a space as simple as the inside of a guitar can have.

A modern piano has no bottom, encloses no space, and therefore has no air resonance modes. This fact has mislead acousticians, organologists, and builders to overlook the existence of air modes when studying historical strung keyboard instruments, which by contrast, usually have closed bottoms. This means that most Viennese and South German pianos of the Classical period are acoustically much closer to guitars, cellos, or harps than to their modern equivalents.

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Permalink Reply by BUGGY (C) on August 22, 2012 at 1:32am

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Permalink Reply by RTZGUITARS on August 22, 2012 at 2:50am

I thought Oily was crazy but Bug your moving in on him, this is some good stuff the vid are great. I find the less stuff             in the box the louder but brighter it sounds. You put a little weight in the box bigger through neck or attached                       to the top you get a darker softer sound. Most boxes are too thick and heavy to have much resonance as far as           guitar tops go. Sanding the box thinner is next on my list of things to try. Sealing the box good helps alot.

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Permalink Reply by The Phrygian Kid on August 22, 2012 at 3:10am

This has all wondered off topic, cos none those c f martins got grommets and bits of metal on em....

Dead right about pianos tho.. This is why all those lovely antique ones are quieter but got a lot more warmth and character..

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Permalink Reply by Ron "Oily" Sprague on August 22, 2012 at 3:24am

Being crazy, and therefore not knowing when to stop, I could launch another git-tech grenade into the resonance mosh pit, and say something provocative like "90% of tone is in the player's fingers, anyway, so all this discussion of resonance of tiny little boxes is just so much phlogiston."

But that would be neither polite, politic, nor completely true. Besides, I stole it from numerous articles on the subject in Guitar Player >:-E

I also have to agree, empirically, with RTZ, that sealing the box good ( thereby stiffening the "frame" to which the resonating top - or bottom - is attached ) certainly seems, to my ears, to improve tone.

Bug, somewhere around here about 6-9 months ago, I posted a link to an online PhD dissertation showing the same resonance characteristics as the Rossing, et al study, but in a Java app. Instead of just the top, it shows how the entire guitar, including the neck, variably flexes in response to different frequencies. It's fascinating to watch. I'll have to dig around and see if I can locate it.

The other kewl thing about the pic Bug shows above is how the soundhole is acting like a speaker port.

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