Soundhole size

[rod]

In a previous post of mine I was asked what size the sound-hole was..This has started me thinking on it,and what are the effects of different sized holes?? I imagine if to small the guitar would lack volume and sound a bit "tinny" ?, and to big a bit drummy maybe???(don't you just love my big technical words)....I thought I might do the current one 108mm just to find out, or is this a bad idea??......
Nicks seem to be a bit larger than other builders by his pictures,or is it just my imagination?

[Bob Connor]

Smaller soundhole = more bottom end
Larger soundhole = more top end


Clarence White had a Martin D28 which he enlarged the soundhole so that his solos would cut through more. I believe Tony Rice now owns that instrument. These two blokes are Bluegrass legends if you are not familiar with them.

Regards

[kiwigeo]

A large soundhole is also useful for retrieving stuff youve left inside the guitar during construction

[bernm]

might be good too for those times when the pick drops inside too ...

Can I elaborate on the original question with a couple of others that popped into mind as I read?

How is the sound affected not only by a bigger or smaller soundhole, but when you also put a soundport (is that what they're called?) in the side. I guess I'm asking for example, if you had a standard sized soundhole, but added a side sound port, then is that sort of achieving something like enlarging the soundhole since there is more 'hole' overall? Or is something different happening entirely because both are in different places?

What about if you go for no soundhole at all but just have a soundport, how does that generally affect top/bottom end?

(I don't actually plan to build using soundports, but these questions came to mind.)


Thanks
Bern

[Dominic]

Hi Bern, the issue of sound ports seems to remain controversial. You can read a lot about them on the OLF.

Most seem to agree they have no impact on the sound at all, that they act independently of the soundhole. Blind tests seem to confirm this although that does not mean all luthiers will agree. As with many things we do and despite evidence or mathematical truth, people will only agree to disagree. But it doesn't seem to be the case that adding a soundport effectively increases the size of the soundhole and increases the top end. The sound port seems to act as a personal montor so the player hears something similar to what people sitting in front hear. I always like to listen to a mate play my guitars before I can judge how they sound but as most people play for and by themselves a soundport can give the player a nicer experience of the true sound of the guitar.

Others may have a different angle on this so read on.
cheers
Dom

[Nick]

Nicks seem to be a bit larger than other builders by his pictures,or is it just my imagination?

Have a look up on the net about a dude called Heimholz Rod ( http://www.phys.unsw.edu.au/jw/Helmholtz.html is one article that discusses soundhole size about 3/4 the way down) , each box has an 'ideal' size for it's volume but as Bob more succinctly put it, you can play with this ideal to get a different frequency balance out of the guitar.
My latest guitar gives the impression that it might be bigger but is essentially the 'right' size for my soundbox, the body size was based around a OOO which has traditionally had a 100mm (4 inch) diameter soundhole, all I did was turn a roundhole into an oval (105 across & 95 wide so the total area remains the same) and made it the width of a binding strip bigger, with the darker binding strip it makes the hole in the spruce bigger. Also to add to the illusion (if you could call it that), I've made the waist a little narrower so the soundhole looks like it fills the top a little more. The Maccaferri I build has a 'D' shaped hole, I just do a reproduction of the original but these are a much larger soundhole again!

[graham mcdonald]

Soundhole size is not a matter of more top end or low end, but it controls the frequency of the air resonance of the body, on a guitar usually somewhere between F# and A on the bottom string. Increasing or decreasing the size of the soundhole will shift the resonant frequency up or down, but the change, from memory, is something like a 15% change in size for a semi-tone shift in the resonance frequency and that is the determinant for the warmth of the bottom end. What is just as important is where and how big the soundboard resonances are in relation to to the air resonance and that is where the top end come from. Al Caruth wrote a series of three articles in American Lutherie a few years back, and Graham Caldersmith wrote papers on the same topic when he was working on his classical guitar 'family', from an acoustic bass to an instrument tuned a fourth high than standard.

cheers

graham

[rod]

I have cut this one at 108mm just to experiment for myself,and it looks so much BIGGER..........bit unsure of it now.It is a lovely piece of spruce though,so it will be going on!!!Will get a picture up tomorrow........Thnx for all of the great advice ...........You are champions!

[Nick]

I have cut this one at 108mm just to experiment for myself,and it looks so much BIGGER..........bit unsure of it now.It is a lovely piece of spruce though,so it will be going on!!!Will get a picture up tomorrow........Thnx for all of the great advice ...........You are champions!

You can always add a binding strip to it if it gets the better of you Rod . It will be interesting to see the results & your impression.

[Rod True]

Aren't all holes in the guitar ports for sound....? Assuming they aren't plugged that is.