Can Strings Cutting Into Bridge Cause Buzz?

[Jeff Schiefer]

Hey All, newbie on this forum, so please excuse me if this has been covered before.

Looking for some advice on an issue I'm having with a Yamaha FG340, circa 1980. Several years ago, I installed an under-bridge pick-up, and did some other work on the guitar– replaced some frets, replaced plastic nut with bone, replaced old plastic saddle with bone saddle, lowered the action a little (lowered saddle, adjusted truss rod).

Over time, the strings seem to have cut into the bridge wood in front of the pins pretty deep. I get a real twangy sort of buzz from the high E and B strings when played open. I discovered if I put some shims under the strings in the grooves they cut in the wood, I eliminate the twang/buzz. (Using thin pieces of plastic for shims.)  Since this fixes the twang, would you say the issue has to do with the grooves, or with the saddle being too low on that end? The saddle is not that old, and barely any groove wear in it, but it is pretty low on the first E side. The strings look like they are making decent contact with the saddle. I use Light gauge strings.

I ordered a new saddle, intending to shape it to sit a little higher on that end, but I hate to raise the action again if I don't need to.

Any suggestions/thoughts?

I don't understand why the shims are correcting the problem for me when I know many people ramp from the string holes intentionally. I can attach some photos if it will help diagnose the issue (if there is an option for attaching photos here).

Thanks in advance for any suggestions.

[Paul Breen]

If you are getting string buzz open but not fretted, that would usually point to a problem at the nut. Can't really comment on it beyond that without having it in front of me.

You may be stuck with the saddle low on the treble side to have your action be where you want it. You can also shim the saddle a bit higher if you want, so no need to spend money replacing a perfectly good one. Shim between the bottom of the nut slot and the under saddle pick up if you need to shim.

I think you would benefit from adding string slots to the bridge, especially with the under saddle pick up. Ramping is actually a better term, the slots begins almost vertical out of the bridge plate but then angles and curves toward the saddle. The idea behind them is to help increase and equalize the string pressure on the saddle at each string, this helps balance the transducer output at each string.

Bridges that have been slotted should have the flute in the bridge pin turned away from the string or replaced with pins that have no flutes cut into them. This forces the ball end of the strings to plant firmly on top of the bridge plate. Pins with flutes combined with bridges that have no slots, will let the ball end erode/ burrow into the pin flutes where it is half on and half off of the bridge plate. This will eventually lead to damage to the bridge plate. I think all pin bridges should be done with string slots but it is an extra step in manufacturing, so it is mostly not done on factory instruments. Doing this can also benefit acoustic tone.

[Jeff Schiefer]

I just put new bone bridge pins in it, which are fluted. I know the  ball ends need to be up under the plate, (not at the bottom of the pins, or stuck in the flutes). I know most of them are seated that way, not sure about the 1st E. That pin popped out after I had them all in, and was tuning up. When I re-strung that one, I tried to bend/curl that string end so it would seat correctly but I need to check it visually with a mirror. I plan to file/sand down the ends of the pins to a 45-degree angle to help keep the ball ends from possibly sticking in the flutes. Was going to do that same time I did any other work, while the strings were off.

If problem is the nut, what do you look for? And how do you correct?

It looks like the strings have done their own ramping, but honestly, I don't know if there were slots in the saddle from the beginning, vs how how much the strings have worn in over time.

What do you shim with that doesn't negatively impact tone?

Pix to come.

[Jeff Schiefer]

Having trouble adding pix. Trying again now.

May have to do some in reply below.

[Jeff Schiefer]

Trying to add pix, but they won't upload. Okay, they finally uploaded.

I think you may be right about the nut. I took the shims out from under the strings at the bridge. And it only was buzzing when played hard and open.

Measured space between the 1st fret and 1st E string. It is really close. Using the strings I just took off as a rough gauge, I could get the B string through the space but not the G string. In the gauge/brand I'm using, that puts the gap at about . 016 - .02. So I'm thinking that's where it's buzzing. The second fret is also really close.

The B-string is equally close to the first two frets.

Also, looking at the bridge, I'm thinking the string slots were there all along. They look to regular, and intentional. The strings do get stuck in them sometimes when I'm changing. But I think the guitar came slotted from the factory. Yes, I'm officially an idiot.

Will post some photos of the nut further below.

[Hesh Breakstone]

Pics please?

This guitar may need a neck reset and that also means that to get the action that you desire you or someone else may have taken the saddle down so very far that the break angle is insufficient.

When the saddle break angle is lacking the vibrating wave of the string breaches the contact point with the saddle effectively creating changing length speaking length for the string.  Hence the buzz and sometimes when this is true at the nut end a sitar sound.

Paul brings up a great point too that nut issues can often sound like saddle issues.

The break angle may also be sufficient for a very light touch but dig in and along comes the buzz.

Anyway pics would help and it also would be helpful to know if the work that you mentioned was professionally done or you did it yourself.

Lastly if the break angle over the saddle is sufficient the string after the saddle, embedded in the bridge, top, plate, etc. is out of play and this is why I question the break angle.

[Jeff Schiefer]

I will try to get some pix tonight. The strings seem to have done their own ramping!

I did the work myself, after a lot of reading up on what/how. I'm pretty decent at woodworking, and it's not an expensive high-end guitar, so figured I'd give it a shot. That was probably around 10 years ago. I don't play this guitar very much, but my son recently bought one, so have had it out more lately.

I have the neck pretty much dead-straight. I just put new bone bridge pins in it, which are fluted. I know the string ball ends need to be up under the plate, not at the bottom of the pins, or stuck in the flutes. I need to do a little work on the pins to get them to seat all the way it. Right now they are holding the strings okay, but the tops are sitting a little higher than the stock pins. One fit in all the way.

Pix to come.

[Jeff Schiefer]

Added some photos in my reply to Paul above. Adding some more here Hesh.

See my reply to Paul.

Also checked the ball ends last night with a mirror. They are all seated correctly.

[Paul Breen]

Jeff, the E string does look low in your picture. I don't use an unfretted measurement from the top of the first fret to the bottom of the string though. There have been a few threads here discussing various methods for determining and setting string action at the nut.

One here from a quick search: http://fretsnet.ning.com/forum/topics/neck-relief?id=2177249%3ATopi...

I'm sure there are others. You should also check our hosts site: http://www.frets.com/FretsPages/Luthier/Technique/Setup/BuzzDiagnos...

The nut can be shimmed or replaced and the slots then cut to a correct depth. You'll need to do some research to familiarize yourself with a method that suites you, there are several ways to get this done. You would also need some nut files to cut the slots (best) or do some research to find out what other tooling shade tree repairer's have had success with.

[Jeff Schiefer]

Paul, what would you suggest to shim the nut with?

The nut was replaced several years ago, but I did not cut the grooves. So pretty sure it came pre-cut.

[Mark McLean]

Jeff

Paul and Hesh have given some good advice here (as usual).  Your photos now demonstrate some of the reasons for your problems – pretty much as they predicted. 

The saddle is very low on the treble side, so that there is insufficient break angle over the saddle on the 1^st string.  This is very likely to be causing trouble.  This is the common scenario of guitars of a certain age: (1)  constant pressure from the string tension makes the neck angle creep forward, (2) action rises because of the changing neck angle, (3) this makes someone file down the saddle, (4) low saddle improves the action but you then lose the break angle and get buzz, low volume and poor performance from under-saddle pickup. 

If you could tolerate the action being higher you could replace that saddle with one that is taller on the treble side (you don't have a problem on the bass strings), or you could put a shim under the current one.  But if your action is already on the high side (I am guessing that is why the saddle got taken down) then you need to address the question of the neck angle. 

Check the neck angle with a straightedge laid on top of the fretboard and see where it hits the bridge.  Instructions here for interpreting the result: http://www.frets.com/FretsPages/Musician/Guitar/Setup/NeckAngle/nec...

What can you do if the neck angle is off?  Well the string ramps (slots) help a bit to improve the break angle.  The ramp slots in yours are already fairly well cut.  I don’t think you are going to get it much better by cutting deeper.  You can plane or sand down the top of the bridge, so that the current saddle stands more proud above the top of the bridge and the break angle increases.  But no professional luthier would recommend that strategy unless it was a really chunky bridge.  Causes still more problems.  Ultimately, the best solution is a neck reset. Yes - that is drastic and expensive.  But if bad neck angle is the root cause of your problems it is the only real solution.  If this Yamaha is not worth enough to you to spend that kind of money - well, you might need to find a new favourite guitar.  Keep the Yamaha and set it up for slide playing where a high action is not a problem!

Looks like the action at the nut is low also.  The 1^st string slot might be a bit low and the open string vibrates against the 1^st fret.  Our esteemed host, Mr Ford, has provided instructions for checking that here: http://www.frets.com/FretsPages/Musician/GenSetup/NutAction/nutacti...

You can repair a too-low nut slot by filling it with CA glue ("super glue") mixed with baking soda, or CA mixed with bone dust.  You would then need to recut a new slot.  If you don't have the files and the experience to do this it might be better to take it to an experienced luthier. 

Best wishes

Mark

[Paul Breen]

Jeff,

What you shim the nut with will depend on whether or not you have the tools to deal with the nut slots afterwards.

I don't know what your abilities are or what tools you may or may not have. I have been using .020" bone shims from LMI. I super glue them to the bottom of the cleaned and sanded nut, then file and sand flush, finishing up with a buff up. This would then require re-cutting the slots to an appropriate depth. Sometimes I'll use a Mahogany shim on Mahogany necks or Maple on Maple necks but still prefer CA attached bone shims. If you can't do that, you can do a shade tree shim job with some thin paper, string packages work OK.  Or, as Mark has suggested, CA and baking soda to fill the slot but you will need to then re-cut it. I use bone dust if I do this type of fill but I haven't for some time. I much prefer adding a bone shim and re-cutting the slots. The CA trick does mostly work and is better suited to plain rather than wound strings.

You saddle does look rather low on the treble end but I have set up many guitars that are border line neck reset with them that low. If you can get the strings at the low end to clear the bridge and ring clearly (bell like, no fuzziness) when plucked and it plays well, run it.

[Jeff Schiefer]

Read the link in Mark's reply about checking nut action...

Checked the string height by holding down the 1st E between the 2nd and 3rd fret... the string is practically sitting on the fret. I can get a piece of notebook paper through it, but that's it. I took a cut piece of the old high E string (.016 diameter), and that would not pass through cleanly. So I definitely think this is a nut issue. I don't have a string action gauge to check it at the 12th fret. Have not checked the neck angle relative to the body of the guitar/bridge yet. Will do that tonight.

In looking at the photo I took of the nut, I can see how there is room in the first 2 slots to raise those strings– if I could fill the slot and re-cut. But no, I don't have any nut files or saws.

I have an extra bone nut (too narrow for my neck)– I can get bone dust from that, and do the CA thing, if I had something to dress the slot with afterwards. I know that's a hack fix. But would probably be the easiest thing at this point.  Now if I could just find a hack substitute for the files. (I know the slots have to be dead-on accurate, done right.)

This guitar is not worth a big investment in a set of good files, a neck re-set, etc.  And I just spent $60 on new strings, new bridge pins, new saddle, and some other stuff, and am saving for a new guitar. So I have to weigh the options at this point.

Thanks for the suggestions and help everyone.