I've been searching through the articles on this site for information on selecting the position where the bridge should be. Obviously on an unfretted instrument you can move the bridge and experiment, but on a fretted guitar, once the frets are on and the neck is fixed that's it. You have committed yourself.

 

So is there any way to know on a box for box basis (not using formulas because I'm pretty sure that they are worthless unless you always use identical boxes) where the bridge should be to get the best results?

 

Now I've already done some test, but I don't know if they are the work of a visionary (don't laugh) or a pointless waste of time (odds on the latter). I was thinking that as far as the box is concerned it gets most of the string vibration through the bridge. If you want to simulate vibrations coming from the bridge can you use something else that will transmit vibrations and see (or rather hear) how they sound and make a choice based on that. I found a tuning fork and tried it at various places on three boxes that I intend to use soon.

The results from the three were quite different. Not surprisingly all gave the warmest and clearest sound in the centre of the box. The top one gave quite progressive results getting better quite gradually towards the centre. The left hand one was very even across it's width until right near the edge. The right hand one was a surprise as it sounded best right in the middle, tone falling off and getting soft of nasal even an inch away from the motif. Shame as I don't really want to put a bridge right on the motif but my tuning fork test suggests that it may be the best place.

 

So, finally, to the question. Has anyone done any tests - similar or otherwise - that give a good indication of where to put a bridge and that do not rely on ratios or formulas, but take into account the different characteristics of each box?

 

 

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Replies to This Discussion

There is no test, as the instrument will change in sustain and tone as you add the neck, braces, end blocks, etc. The best place to put the bridge is where it seems to have the maximum effect on the top. On a cigar box, the tone isn't going to be great anyway, and the finished product will reflect your workmanship. Integrity of glue joints, removable of paper at the joints so there are good bonds that don't inhibit resonance, bond of the neck to the box, and many other factors will determine the final result as a whole. Even if you found a better sweet spot on the finished guitar, it won't matter, as the scale length and fretting has determined where the bridge will live. You just live with how the CBG sounds. If you are looking for critical soundboard tone, the CBG is not for you. The bottom line is that a guitar made from a cigar box won't have a sweet spot that would change significantly by bridge placement that would affect what the final instrument will sound like. The player makes the CBG come alive, with good slide work, and a kickin' amp. 

This is an inspiring thread, just the tuning fork idea is a step more than I'd done, so thanks.

Richard, I understand your point that it is, after all, a cigar box, but I enjoy aiming for the best possible results, just being freed up by the fact that it is only a cbg. Aiming for perfection within the constraints is a big part of the fun. 

 

On my first build I tried placing the bridge between the f-holes, as in violin family instruments. I'd read that they placed there to let the top move in a twisting manner (as viewed down length of neck, say) in response to the strings. No idea if it really worked (nothing similar to compare to) but I got a great sound out of a birch ply top (not a real cbg, made from gf's dresser and that ply). Over a couple months it started to bow inward so I  opened it up and added two sound posts. Louder but not as rich. If I were to do i again I'd just try a post and bass bar or just bracing....

Sorry to side track a bit here, but Richard, would you mind posting a photo of how you've done fan bracing on a cbg? Is that your photo as the icon for this group? Also, when you say birch, do you mean birch ply or are you using real tone wood? I see you put a lot of effort into the boxes themselves, they're great looking.  I want to return to making the boxes themselves and try using good materials. 

 

Here's a photo of that first build no you can see the f-hole vs. bridge placement. Top really vibrated before adding posts, now less so but back vibrates more to make up a bit. Please overlook how rough it is, I made it with almost no tools out of my girlfriend's dresser, some ply and scrap wood using a glue gun so it is ugly and primitive, replaced fretboard later. Made nicer ones since but still play this the most. You can even see the blood stains on the top where I literally played till I bled :) 

Lastly, how about just making it electric on the one you don't like the ideal bridge location for, a magnetic pup would make that matter less, right?

Hmmm. If this is an itch you need to scratch, than scratch it.

1) using your tuning fork, find the sweet spot on your boxes. Mark with pencil.

2) build fretless, move bridge around and find if the sweet spot has moved (bet it has!) Do NOT glue things in place! Measure what you're scale length is.

3) disassemble. Feed the scale length to a fret calculator (like Stew Mac's) and cut fret slots, etc. Reassemble.

This would be tough to do on a standard guitar, because the neck tapers and it would be a bugger keeping the centerline at right angles to the slots. But if your CBG neck is straight, this shouldn't be a major problem. You will probably end up with a weird scale length, but so what? Unless you HAVE TO HAVE the same scale as your stratocaster, it's not carved in stone. Look how Gibson has changed over the years.

 

You sound like one of those people for whom "good enough" just ain't good enough. I salute you. And while a CBG will never be a "concert quality" instrument, the things you learn quick and cheap with CBG's could well set you on the path to being a master luthier when you DO start making concert instruments.

I love this thread. Thanks John. Anyway, The CBG that is one of my icons is gone, spirited away by a player who just had to have it. I liked the two Frankins he gave me. My surprise at his offer at a jam tickled me.  It was the first of light fan braced tops, and sounded especially good. It had an internal steel strut to prevent the thing from folding, and probably adds a lot of sustain. It was a lot of work, but the acoustic sound was very good. Very surprised. I carefully trimmed the joints so there was all wood at any glue joint. I also try to get the best tone from CBGs. I didn't mean to not to try to get the best tone. I just copied an open guitar top. There were six very light poplar braces arranged in a sunburst or rising sun pattern. I thought it looked neat. The thing sounded amazing. I use solid Birch, and lately OKUME, a ply formed under high pressure, and used in marine work. Has a sweet lively  "hard" tone. I saw it used in autoharps, which are under tremendous string pressure. The sound of the ply harp was better than most solid wood harps. I love these CBGs. 

Tophat Commode said:

This has been one of the most interesting discussions on CB Nation--I've been learning quite a bit following it. I've always just let the harmonics on the 12th, 5th, and 7th fret determine final bridge placement at the end of a build, but having just finished a CB tenor uke that has all the resonance of a brick I've been thinking about abandoning neck-thru design and putting as much pressure on the box as I can to increase resonance...or else just concentrate on accurate fretting,bridge placement(determined by ringing the harmonics in a dry fit), string height at nut and bridge and, ultimately, superior electronics...Thanks John, for starting an inspiring and informative discussion!

Fitzhugh said:

This is an inspiring thread, just the tuning fork idea is a step more than I'd done, so thanks.

Richard, I understand your point that it is, after all, a cigar box, but I enjoy aiming for the best possible results, just being freed up by the fact that it is only a cbg. Aiming for perfection within the constraints is a big part of the fun. 

 

On my first build I tried placing the bridge between the f-holes, as in violin family instruments. I'd read that they placed there to let the top move in a twisting manner (as viewed down length of neck, say) in response to the strings. No idea if it really worked (nothing similar to compare to) but I got a great sound out of a birch ply top (not a real cbg, made from gf's dresser and that ply). Over a couple months it started to bow inward so I  opened it up and added two sound posts. Louder but not as rich. If I were to do i again I'd just try a post and bass bar or just bracing....

Sorry to side track a bit here, but Richard, would you mind posting a photo of how you've done fan bracing on a cbg? Is that your photo as the icon for this group? Also, when you say birch, do you mean birch ply or are you using real tone wood? I see you put a lot of effort into the boxes themselves, they're great looking.  I want to return to making the boxes themselves and try using good materials. 

 

Here's a photo of that first build no you can see the f-hole vs. bridge placement. Top really vibrated before adding posts, now less so but back vibrates more to make up a bit. Please overlook how rough it is, I made it with almost no tools out of my girlfriend's dresser, some ply and scrap wood using a glue gun so it is ugly and primitive, replaced fretboard later. Made nicer ones since but still play this the most. You can even see the blood stains on the top where I literally played till I bled :) 

Lastly, how about just making it electric on the one you don't like the ideal bridge location for, a magnetic pup would make that matter less, right?

I like them cool F holes. Very cool CBG. 

Richard Sanabia said:

I love this thread. Thanks John. Anyway, The CBG that is one of my icons is gone, spirited away by a player who just had to have it. I liked the two Frankins he gave me. My surprise at his offer at a jam tickled me.  It was the first of light fan braced tops, and sounded especially good. It had an internal steel strut to prevent the thing from folding, and probably adds a lot of sustain. It was a lot of work, but the acoustic sound was very good. Very surprised. I carefully trimmed the joints so there was all wood at any glue joint. I also try to get the best tone from CBGs. I didn't mean to not to try to get the best tone. I just copied an open guitar top. There were six very light poplar braces arranged in a sunburst or rising sun pattern. I thought it looked neat. The thing sounded amazing. I use solid Birch, and lately OKUME, a ply formed under high pressure, and used in marine work. Has a sweet lively  "hard" tone. I saw it used in autoharps, which are under tremendous string pressure. The sound of the ply harp was better than most solid wood harps. I love these CBGs. 

Tophat Commode said:

This has been one of the most interesting discussions on CB Nation--I've been learning quite a bit following it. I've always just let the harmonics on the 12th, 5th, and 7th fret determine final bridge placement at the end of a build, but having just finished a CB tenor uke that has all the resonance of a brick I've been thinking about abandoning neck-thru design and putting as much pressure on the box as I can to increase resonance...or else just concentrate on accurate fretting,bridge placement(determined by ringing the harmonics in a dry fit), string height at nut and bridge and, ultimately, superior electronics...Thanks John, for starting an inspiring and informative discussion!

Fitzhugh said:

This is an inspiring thread, just the tuning fork idea is a step more than I'd done, so thanks.

Richard, I understand your point that it is, after all, a cigar box, but I enjoy aiming for the best possible results, just being freed up by the fact that it is only a cbg. Aiming for perfection within the constraints is a big part of the fun. 

 

On my first build I tried placing the bridge between the f-holes, as in violin family instruments. I'd read that they placed there to let the top move in a twisting manner (as viewed down length of neck, say) in response to the strings. No idea if it really worked (nothing similar to compare to) but I got a great sound out of a birch ply top (not a real cbg, made from gf's dresser and that ply). Over a couple months it started to bow inward so I  opened it up and added two sound posts. Louder but not as rich. If I were to do i again I'd just try a post and bass bar or just bracing....

Sorry to side track a bit here, but Richard, would you mind posting a photo of how you've done fan bracing on a cbg? Is that your photo as the icon for this group? Also, when you say birch, do you mean birch ply or are you using real tone wood? I see you put a lot of effort into the boxes themselves, they're great looking.  I want to return to making the boxes themselves and try using good materials. 

 

Here's a photo of that first build no you can see the f-hole vs. bridge placement. Top really vibrated before adding posts, now less so but back vibrates more to make up a bit. Please overlook how rough it is, I made it with almost no tools out of my girlfriend's dresser, some ply and scrap wood using a glue gun so it is ugly and primitive, replaced fretboard later. Made nicer ones since but still play this the most. You can even see the blood stains on the top where I literally played till I bled :) 

Lastly, how about just making it electric on the one you don't like the ideal bridge location for, a magnetic pup would make that matter less, right?

Right on Alan. I'm making a fretless CBG. started it last week. I picked up a fretless electric bass, and now I'm having too much fun...

Alan Roberts said:

Hmmm. If this is an itch you need to scratch, than scratch it.

1) using your tuning fork, find the sweet spot on your boxes. Mark with pencil.

2) build fretless, move bridge around and find if the sweet spot has moved (bet it has!) Do NOT glue things in place! Measure what you're scale length is.

3) disassemble. Feed the scale length to a fret calculator (like Stew Mac's) and cut fret slots, etc. Reassemble.

This would be tough to do on a standard guitar, because the neck tapers and it would be a bugger keeping the centerline at right angles to the slots. But if your CBG neck is straight, this shouldn't be a major problem. You will probably end up with a weird scale length, but so what? Unless you HAVE TO HAVE the same scale as your stratocaster, it's not carved in stone. Look how Gibson has changed over the years.

 

You sound like one of those people for whom "good enough" just ain't good enough. I salute you. And while a CBG will never be a "concert quality" instrument, the things you learn quick and cheap with CBG's could well set you on the path to being a master luthier when you DO start making concert instruments.

I am thinking along some of the lines of the others...determine were the loudest response is on the cbg with the tuning fork...you can't go wrong with ANY Padron box...everyone was a winner.  anyway, measure from your sweet spot to the edge of the box were the neck will be placed, subtract from your desired scale length and press on..determine the number of frets and overall length of your neck and headstock.

I have found that I like to place the bridge on the bottom of the box.  that way, when you cut a central sound hole, you can see the picture inside the box...( I have a couple of Uke pictures on my page that show this)

The tuning fork will provide the vibration drive necessary to determine the natural frequency of the box.  If you had a spectrum analyzer, you could really see what frequencies the box responds to.  I did read a paper from someone doing this with a ukulele at some university, Michigan state I think.  do a google search for frequency response of a cigar box ukulele and you might find it... good luck!

 

Can I just pick up on one point. The sort of "near enough is good enough" approach (which was how I was reading an earlier comment). I don't think anyone builds that way. Just looking at the instruments in the photo gallery. People care. In which case if something might help and doesn't require much effort why wouldn't you?

 

Of course the main question is will it help. Not sure yet, but just listening to the contrast in sound between the different parts of that one box makes it very difficult to believe that optimising bridge position in this way wouldn't be useful.

 

> Can I just pick up on one point. The sort of "near enough is good enough"
> approach (which was how I was reading an earlier comment).
> I don't think anyone builds that way.

I think for most builders the point of diminishing returns continues to move. For your first build - you hit it really quickly and are usually happily shocked by having an instrument that's even playable. But by your tenth build you've got better tools, perhaps some templates and fixtures, and much better technique. And you're going for better sound. This is natural and fine.

So, wanting the best sound easily achievable shouldn't be confused with an unrealistic pursuit of perfection.

BTW, I was told at one point that the bridge should be 1/3 to 1/4 up from the end of the box and the hole roughly centered. In my experience this is far from ideal. I have no idea what the basis for those erroneous recommendations were.

Right on Ken. I saw that bridge placement also, and found it odd. I place the bridge in the center, and the hole near the end of the fretboard. 

ken farmer said:

> Can I just pick up on one point. The sort of "near enough is good enough"
> approach (which was how I was reading an earlier comment).
> I don't think anyone builds that way.

I think for most builders the point of diminishing returns continues to move. For your first build - you hit it really quickly and are usually happily shocked by having an instrument that's even playable. But by your tenth build you've got better tools, perhaps some templates and fixtures, and much better technique. And you're going for better sound. This is natural and fine.

So, wanting the best sound easily achievable shouldn't be confused with an unrealistic pursuit of perfection.

BTW, I was told at one point that the bridge should be 1/3 to 1/4 up from the end of the box and the hole roughly centered. In my experience this is far from ideal. I have no idea what the basis for those erroneous recommendations were.

Hi Ken and Richard (and anyone else who can be bothered to read this).

 

I think I understand the law of diminishing returns as I got very into Hi-Fi at one stage. That particular law dominates the Hi-Fi market. The point is that the outlay for this is trivial. Many people may already have a tuning fork and they are very cheap if you fancy getting one. Lots on eBay.

 

Coming back to the first time builder. I think it depends why you build them. I build to play. At this stage I don't intend to sell them or make a huge quantity. Once I have what I want to play on I may not make any others. I don't know. But with this in mind I want the best sound I can possibly have because I want people (and that includes me) to think that I can play well.

 

One thing that my limited tests have shown (limited by the small number of boxes that I have) is that each box is very different and that is where the 1/3 to 1/4 rule, or any other rule, falls down. It takes no account of the differing construction and materials of the boxes. The tuning fork test is intended to do exactly that. Give an indication of the characteristic of the actual box that you have in front of you.

 

Of course to test the test, I (or someone else, preferably) should get at least two boxes that respond the same to the tuning fork and build one according to the fork test and the other with the bridge at a very different place and see how they sound. I'm not about to do that. I have a tuning fork. It takes 30 seconds or less to test. For a cost of half a minute of my time and no money (and with the chance of improved sound) why wouldn't I? It really is that simple.

 

I will be trying the tuning fork idea on my next build...At some time I should be making a duplicate of existing guitars and can then compare the differences..I do have some favorite boxes and tend to use these for multiple builds..

John H. Maw said:

Hi Ken and Richard (and anyone else who can be bothered to read this).

 

I think I understand the law of diminishing returns as I got very into Hi-Fi at one stage. That particular law dominates the Hi-Fi market. The point is that the outlay for this is trivial. Many people may already have a tuning fork and they are very cheap if you fancy getting one. Lots on eBay.

 

Coming back to the first time builder. I think it depends why you build them. I build to play. At this stage I don't intend to sell them or make a huge quantity. Once I have what I want to play on I may not make any others. I don't know. But with this in mind I want the best sound I can possibly have because I want people (and that includes me) to think that I can play well.

 

One thing that my limited tests have shown (limited by the small number of boxes that I have) is that each box is very different and that is where the 1/3 to 1/4 rule, or any other rule, falls down. It takes no account of the differing construction and materials of the boxes. The tuning fork test is intended to do exactly that. Give an indication of the characteristic of the actual box that you have in front of you.

 

Of course to test the test, I (or someone else, preferably) should get at least two boxes that respond the same to the tuning fork and build one according to the fork test and the other with the bridge at a very different place and see how they sound. I'm not about to do that. I have a tuning fork. It takes 30 seconds or less to test. For a cost of half a minute of my time and no money (and with the chance of improved sound) why wouldn't I? It really is that simple.

 

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