What gives a guitar its bass response?

[Mbroady]

Great question from the OP. Not sure I can contribute much but I will say that if I order a guitar sight unseen and it does not have the low end I’m looking for, then back it goes.
I have not had it happen often but it has happened.

[Rmz76]

Originally Posted by GHS

Wasn't it Clarence White that had the large diameter sound hole on his Martin? or am I thinking of someone else? And why did they do it??

Clarence White and then Tony Rice.

[archerscreek]

Originally Posted by TBman

So, if someone made a wood/rubber ring insert that fit inside the circumference of the soundhole of a guitar it would decrease the diameter and the bass would be slightly increased?

If this is so, it's interesting that different sound hole diameters aren't talked about as being a custom build option. Maybe it isn't significant in consideration of the entire build?

Interesting stuff, thanks.

I wouldn’t choose rubber or the like. It soaks up sound and vibration so well that it’s widely used in archery to tame both. Archers put it everywhere-on their strings, limbs, risers, stabilizers, etc, to make their bows quieter and feel more dead in the hand.

Every now and then I see talk of soundhole size as an option, probably because Clarence White’s famous D-28 had an artificially enlarged hole. And since he and Tony Rice, who also played it, were both fantastic musicians who made great music with the enlarged hole guitar, a bigger hole gets attention/consideration. As a huge Clarence White and Tony Rice fan, I admit I did consider soundhole size when I was looking for a new guitar. But I think those guys could sound great on anything.

But I think you touched upon a future guitar model I’ve also envisioned, a guitar in which the owner/player can alter the sound through designed modification possibilities built into the guitar. Andy Powers, are you reading this? I conceived of the idea when playing my dread with the truss rod wrench stuck in. It tightened the sound. I’ve noticed similar changes is sound comparing guitars with electronics installed and without and even changes to guitars with the end pin in and out.

I predict one day, possibly sometime soon, someone will come out with a guitar where we can change the soundhole size, where we can add weights of some sort to pockets inside the body that change the sound, where we can easily swap necks to not only try different shapes but change scale. We could even have adjustable bracing. And we all know we’d buy one of these things to try out because we like to tinker around with things.

[1neeto]

Originally Posted by TBman

So, if someone made a wood/rubber ring insert that fit inside the circumference of the soundhole of a guitar it would decrease the diameter and the bass would be slightly increased?



If this is so, it's interesting that different sound hole diameters aren't talked about as being a custom build option. Maybe it isn't significant in consideration of the entire build?



Interesting stuff, thanks.

I was also thinking something similar. Or maybe cover the sound hole with a radiator style speaker. You ever wonder how come those Bluetooth speakers have such booming bass from such a small size? Radiator speakers. But then again something like that would kill the treble. Just buy many guitars and problem solved! 🤣

[Alan Carruth]

TBman asked:
"So, if someone made a wood/rubber ring insert that fit inside the circumference of the soundhole of a guitar it would decrease the diameter and the bass would be slightly increased?"

Making the hole smaller drops the pitch of the Helmholtz resonance, and thus also the pitch of the 'main air' resonant mode, but maybe not as much. It would also tend to reduce the power of the resonance. Whether it would seem more or less 'bassy' would depend on the balance of those two things, and that's a subjective judgement that is hard to predict.

'Sound ports' add sound hole area, and can change the 'main air' pitch quite a lot. Surprisingly enough, even a fairly large 'port' in a guitar, which alters the 'air' pitch by a fair amount, usually won't make much difference in the timbre to folks out in front. It can make a difference to the player, particularly if it's in a place where they can see it as they play. Remember that low-end sound goes out about equally in all directions, but high end sound doesn't work like that. Highs tend to be more directional; going off the top and out of the hole toward the audience. The player might not hear much of the high end if there's nothing in the room to reflect it back to them. A side port that the player can look into can 'beam' some high frequency toward them.

Some builders make ports with sliding doors that allow the player to adjust the area of the opening, and thus the 'Helmholtz' pitch. I have seen a guitar that had a sliding sleeve in the sound hole that could also be used to adjust the Helmholtz' pitch. Trevor Gore bolts weights to the sides of his guitars to alter the sound, and it would not be hard to build in some adjustment there. Players adjust the mass of the bridge all the time by swapping pins, with variable results. Swapping tuning machines can also affect the tone, but not always.

An analogy like to use in talking about making changes on the guitar is that of 007 tied in a chair, with the water in the room rising. The depth of the water doesn't matter at all until it reaches his nose, and then it matters a lot. Sometimes you make a big change and hear nothing, and sometimes you make a small change and it's major in terms of sound. Often enough, the same change on another guitar does nothing, or even the opposite. There are lots of variables.