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I have been thinking about the size of my sound hole and am wondering how it compares to what other people are using. Right now it is 102 mm or a hair over 4 in. I have a set of OM plans that call for a 3.875” (98.5mm) hole and another book where the guy says 4 in.

So I want to know what do you guys use and what is the acceptable size for a steelstring sound hole? Do you use one size for all your steel string models? What is to big or to small?

Any thought on the subject are welcome.

Josh

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Josh House

Canadian Luthier Supply
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Josh,

I've built only one steel string so far. It has a medium sized box, and I elected to cut a 4" diameter soundhole. Seems to work fine.

One factor about soundholes to keep in mind -- the larger the hole, the more highs and the less lows, while the smaller the soundhole, the more lows and the less highs.

Best,

Michael

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Josh, if you have medium or larger sized hands, 4" is optimum for highs, lows, and getting your hand in there while fussing back and forth with bolt-on necks!

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I use a 4" sound hole on most guitars I build, but I was looking through the SCGC catalog over the weekend and one of their models goes as high as 4 9/16".

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Brock Poling
Columbus, Ohio
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Well so far it doesn't sound like am that far off. I am at least in the range of an acceptable size.

Larry
I know what you are talking about with the bolt on necks. I use a 3 1/2 in. hole with a 12 fret neck on by guitar-bouzoukis. I have large (mind you skinny) hands and it can be a challenge getting those bolts in and out.

Josh

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Josh House

Canadian Luthier Supply
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My cutter is set at 100mm, about 3 15/16", I really don't think it's that critical.

Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

The best sounding guitar I`ve built is a 00 flamed maple with a 3 5/8" hole. Every one who hears this little instrument remarkes about " the big sound ". I`ve built several dreads with 4" holes but none of them approach this little darling. I don`t know if hole size is the key but the next 00 I build will have a 3 5/8" hole!

I played with the soundhole size on my OM guitars and Have come up with a 3.77" soundhole as giveing the best resonance. It will depend on everything from the shape to the internal volume of the guitar though.

Check the archives on this subject. There have been a few discussions on it already and although I don't remember the consensus (that happens a lot lately ), several builders here did feel that 4" plus on an OM does have merit.

Here's a link to one of Sylvan Wells' guitars where he briefly talks about larger soundholes on a small guitar Caribbean 13Roy O38601.4990509259

An interesting thing is that on my 000 and OM the 3.77" is best but on my L-00 I use a 4" to 4-1/8" sound hole which works best. So many variables.

Bracing has an influance on how one hole dia will react compaired to another. 3.7" is large enough for the air volume to be moved on an OM, but I have use 4" for several years. as long as you don't way smaller or larger, say 3.68-4.13 I think you will have good results.

Good point Michael. When I talk about getting better responce with a 3.77 than a 4" I am not talking about much difference, Most people wouldn't even notice the difference. Things such as bracing and thickness of wood will have a much bigger effect than a small change in soundhole size.

Richardarvey38601.618275463

Just to be different, my standard soundhole diameter on guitars/guitar bouzoukis (apart from travellers) is 110mm (4.33"). If I'm doing a side sound port I reduce it slightly. The "physics" is complicated and Alan Carruth has written some interesting posts on this (and other things!) but my guitars have the sounhole pretty forward towards the upper bout, my X brace angle is pretty narrow, and my tops are heavily domed (braces set to about a 15' radius). This all works very well for me and gives good volume/projection and a nice balance across the strings. As others have said - soundhole size in isolation doesn't mean too much - it's how it fits in the total design that counts.

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Dave White
De Faoite Stringed Instruments
". . . the one thing a machine just can't do is give you character and personalities and sometimes that comes with flaws, but it always comes with humanity" Monty Don talking about hand weaving, "Mastercrafts", Weaving, BBC March 2010

This brings up a interesting question.... For those of you that put sound ports in you guitars: Do you decrease the sound hole area by the area of the port, or a percentage ther of? on the few I have experimented with I did not.

Yes, it shure has to be a part of the total construction. But one thing is for shure, a small hole make the airchamber main resonance lower, while a bigger hole tends to make freq higher. So if you have a very stiff or small guitar it may be a good idea to have a smaller hole, or vise versa.

My 2 cents.. or 15 swedish ore.

[QUOTE=MichaelP] This brings up a interesting question.... For those of you that put sound ports in you guitars: Do you decrease the sound hole area by the area of the port, or a percentage ther of? on the few I have experimented with I did not.[/QUOTE]

Michael, I've ported one of my guitars so far, and am building another that will be ported. The guitar that got ported has a standard size soundhole. I ported it after I had finished building it, and the port improved the sound noticeably. I'm sold on them durn things.

Best,

Michael

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If your guitar sounds the way you want it to, then the hole is the 'right' size. It's too big if there's no place left to glue down the bridge. It's too small if you have to point it out to people.

I do reduce the soundhole size on 'ported' guitars. One of the reasons I did my experiment with the 'corker' two years ago was to figure out how much to adjust the 'main' soundhole size. It turns out there is no simple formula.

One thing the soundhole size does is establish the pitch of what I call the "real" 'Helmholtz' air resonance. The 'main air' resonance that you hear is the product of the way that 'real' resonance interacts with the top (ad the back, too, maybe), so you can see that it gets complicated.

If you stick a microphone inside the guitar and measure the sound level in different spots at the 'main air' resonance frequency, what you'll find is that it's highest at the tailblock, pretty high at the neck block, and low at the soundhole location. If you add a port at the tailblock end it vents a lot of pressure, and that changes the pitch of the 'real' Helmholtz resonance a lot. A port just above the waist, right about where the 'normal' soundhole is, has much less effect on the pitch since there is not as much pressure there to vent. If your idea in cutting down the size of the main hole is to keep the pitch of the 'main ar' resonance the same on your ported guitars as it is on your 'normal' ones, then you will have to reduce the hole size more the farther from the main soundhole you put the port. Ditto for the size of the port: bigger port, smaller soundhole. I wish there was some easy rule about this, but there's not.

The soundhole size probably has other effects on the tone. I'm pretty sure there are some high frequency things going on, but need to do some experiments to figure that out. All in due time....

[QUOTE=Alan Carruth]

If you stick a microphone inside the guitar and measure the sound level in different spots at the 'main air' resonance frequency, what you'll find is that it's highest at the tailblock, pretty high at the neck block, and low at the soundhole location.[/QUOTE]

Alan, I find this information very intriguing. I've played around with alternative designs in which the soundhole(s) is relocated to either the heel area or the tail area. But the idea behind these exercises was to be able to develop alternative bracing strategies so I could recapture the middle and upper areas of a guitar for sound production.

So, neglecting the idea of ports for a moment, would it be correct to deduce from this statement that placing a soundhole (or soundholes) at the tail or the heel area would even further increase an instrument's sound propagation efficieny?

Best,

Michael

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Interesting......

Josh

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Josh House

Canadian Luthier Supply
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House Guitars - Custom Built Acoustic Instruments.
http://www.houseguitars.com

Michael:
I can't recommend enough reading Bill Allen's article on air resonances that was in American Lutherie #1, and is out in the first 'Big Red Book'. He's got a lot of stuff about what changes you can expect to hear when you move the hole around.

Soundhole size and location has been an area of design that has been experimented with forever. Every once in while I'll see a picture of some old guitar with an unusual soundhole setup, and some of them are by big names. From what I can see, it's probably all been tried, more than once, by some pretty smart builders. This is SOP in the guitar world: the stuff that works gets put into the 'standard' designs, and the stuff that doesn't gets left out. So you have to ask yourself why a simple change like moving the hole up onto the side, that might make the guitar more efficient, is not 'standard practice'.

I think there are three answers:
1)the change doesn't work,
2)the change works, but doesn't sound good, or
3)it did something that wasn't desireable at the time, but that we might like. Only this last case will make the change 'productive' for us.

We have to realize that, compared to other instruments, the guitar is, in fact, pretty efficient at turning player energy into sound. We could always use more efficiency, of course, given that the amount of energy we can put in is so limited compared to what violinists and pianists can do. However, since a lot of smart people have been trying to do this for along time, it should not surprise us if the improvement is not an easy one.

This is not to say that the guitar can't be made more efficient. I've made 'loud' guitars of several kinds. They tend not to sound very good. There are exceptions, of course: the 'sandwich' top looks promising, for example, but there may be issues with any new technology that won't be immediately obvious. When Henry built the Model T to get farmers into town nobody thought about global warming.

Some things that weren't considered useful before might be now. Side 'ports' may be an example of that. They are particularly nice if you tend to play for your own amusement in a room that is not very reverberant, or if you're playing in a noisy place without amplification. In the past fewer poeple had wall to wall carpet, and music lovers tended to shut up a little better when the guitarist was playing (maybe). It could be that's an idea who's time has come.

Ultimately the 'standard' designs are standards because they sound the way people expect a guitar to sound. If you change something as basic as the location of the hole you should expect the sound to change as well, and maybe it won't be as 'guitarlike' as you'd like it to be. It's possible that that sound will catch on: maybe that's just what poeple want now.

My 'take', at present, is that the guitar as we know it is a remarkably well thought out piece of kit. It is, in many respects, 'optimised', which does not mean it's _good_, it's just as good as you could expect it to be given the level of technology. The more I learn about how guitars work the more I see little tweaks and design elements that can't be changed much without losing something that makes the instrument work. It's a nicely balanced design, and making any one major change will probably entail a whole lot of other major changes to get it to work well again. I'm not saying it can't be done, but I do think you should expect to put in a fair amount of effort to get it right.   

This particular post ought to be required reading for every single maker. Well stated, Alan.


[QUOTE=Alan Carruth] Michael:
I can't recommend enough reading Bill Allen's article on air resonances that was in American Lutherie #1, and is out in the first 'Big Red Book'. He's got a lot of stuff about what changes you can expect to hear when you move the hole around.

Soundhole size and location has been an area of design that has been experimented with forever. Every once in while I'll see a picture of some old guitar with an unusual soundhole setup, and some of them are by big names. From what I can see, it's probably all been tried, more than once, by some pretty smart builders. This is SOP in the guitar world: the stuff that works gets put into the 'standard' designs, and the stuff that doesn't gets left out. So you have to ask yourself why a simple change like moving the hole up onto the side, that might make the guitar more efficient, is not 'standard practice'.

I think there are three answers:
1)the change doesn't work,
2)the change works, but doesn't sound good, or
3)it did something that wasn't desireable at the time, but that we might like. Only this last case will make the change 'productive' for us.

We have to realize that, compared to other instruments, the guitar is, in fact, pretty efficient at turning player energy into sound. We could always use more efficiency, of course, given that the amount of energy we can put in is so limited compared to what violinists and pianists can do. However, since a lot of smart people have been trying to do this for along time, it should not surprise us if the improvement is not an easy one.

This is not to say that the guitar can't be made more efficient. I've made 'loud' guitars of several kinds. They tend not to sound very good. There are exceptions, of course: the 'sandwich' top looks promising, for example, but there may be issues with any new technology that won't be immediately obvious. When Henry built the Model T to get farmers into town nobody thought about global warming.

Some things that weren't considered useful before might be now. Side 'ports' may be an example of that. They are particularly nice if you tend to play for your own amusement in a room that is not very reverberant, or if you're playing in a noisy place without amplification. In the past fewer poeple had wall to wall carpet, and music lovers tended to shut up a little better when the guitarist was playing (maybe). It could be that's an idea who's time has come.

Ultimately the 'standard' designs are standards because they sound the way people expect a guitar to sound. If you change something as basic as the location of the hole you should expect the sound to change as well, and maybe it won't be as 'guitarlike' as you'd like it to be. It's possible that that sound will catch on: maybe that's just what poeple want now.

My 'take', at present, is that the guitar as we know it is a remarkably well thought out piece of kit. It is, in many respects, 'optimised', which does not mean it's _good_, it's just as good as you could expect it to be given the level of technology. The more I learn about how guitars work the more I see little tweaks and design elements that can't be changed much without losing something that makes the instrument work. It's a nicely balanced design, and making any one major change will probably entail a whole lot of other major changes to get it to work well again. I'm not saying it can't be done, but I do think you should expect to put in a fair amount of effort to get it right.   [/QUOTE]

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[QUOTE=Alan Carruth]... Ultimately the 'standard' designs are standards because they sound the way people expect a guitar to sound. If you change something as basic as the location of the hole you should expect the sound to change as well, and maybe it won't be as 'guitarlike' as you'd like it to be. [/QUOTE]
Alan,

Your approach is reasoned as well as reasonable, but oh how I hope you are wrong about this. I know I should just shut up and listen, especially when the ideas I'm cooking are so ethereal as to be mere theories and CAD drawings. Unfortunately, a little voice inside my head is echoing what you are intimating, and even if my "newfangled" design/engineering ideas prove to "work", the instrument I build may very well sound too different from the standard great guitars to be thought of as a positive step, and thus dismissed. I guess I had better make a prototype before wasting any more time speculating.

Dennis

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Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

Alan,

As I was reading through your most recent response, I couldn't help but begin nodding my head. I like to experiment, and I came up with a "totally out there" concept for the second guitar I ever built. The idea was to build a classical with a neck-to-body joint at the 17th fret, and with a 24-fret fingerboard. This required the soundhole to be moved.

After doing a fair amount of 'net searches on alternative soundhole placements, I decided to install twin soundholes whose surface area were the same as a single one. Here's a pic of the guitar. Redwood and padauk. Check out the adjustable bridge -- an idea I borrowed from Manuel Rodriguez. Internally, I elected to use lattice bracing of my own design, with a single under-the-bridge cross brace.



The guitar was somewhat disappointing. It is loud and very bright sounding with decent bass response, but it just sounds different. It doesn't have that characteristic classical sound.

Well, I immediately suspected the soundhole placement as being the culprit, and also perhaps the bracing pattern. I didn't think it was the woods, because the next guitar I built was a traditional classical in every way, except I built it from redwood and padauk. It sounds very nice, I think.

So I decided to try building one more of these 17-fret-to-the-body guitars, which by this time I had begun calling "Zen," but this guitar would be traditional in every way, except for the body joint. Spruce, coco, Torres 7-fan bracing, standard sized soundhole and placement. The only thing I had to do differently was I had to add a couple of fairly beefy angle braces to the top, which ran from the neck heel to the tone bar, so the guitar wouldn't fold up on itself.



Wow. What a huge difference. This guitar has a very powerful Spanish sound quality to it, and despite having almost no upper bout, the basses are quite resonant. Everyone who I have showed it to has been amazed at its sound. Me too.

So, yes, I find myself being in agreement with much of what you wrote. I still get the urge to try different ideas, though. Maybe one of these days.

Best,

Michael

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Live to Play, Play to Live

Michael:
Cool!

I'm all for experiments, having done a few myself, but I think you have to look at them as 'learning experiences' and not commercial ventures if you're to avoid dissappointment.

There's a pretty wide range of stuff that will sound 'guitarlike', but if 'great' is what you're after it's a lot easier to get it by sticking with 'standard practice'. OTOH, my most Spanish' sunding classical to date has X bracing and a body the size of a 12-fret 000.

'The Guitar' is a different thing now than it was 100 years ago, or even, in many ways, 50 years ago. It's always chaning and evolving to suit the demands of the moment, and that's as it should be. Heaven preserve us from ever getting into the mindset of the violin world!

Michael - interesting guitars. Rene Baarslag makes something similar - a 15 fret to the body instrument. Check it out: http://www.granadainfo.com/reneyana/renehires15.htm

I played one, and I remember it being a very nice instrument.jfrench38607.5651157407

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