Advice on a slightly reverse bowed neck

[Wilmywood]

I picked up a 1978 G-37 blonde with a maple neck the other day. The story was this woman's brother bought it in 1978 and died in 1980, she got the guitar and it had been in the case ever since. It looked ok, had one minor graunch in the top but looked ok otherwise. It's spruce top, all maple body, archback and maple neck with a rosewood fret board. All the strings were old and loose on it.
Got it home and decided to bring the string tension up on the old ones before installing new. It has some buzz on the thinner strings. So, I pulled the TRC and checked and the truss rod was not loose, but not very tight either. I tightened it a half turn and as I feared the buzz got worse, so I backed it all the way off, left a slight gap, and still had the buzz. So I tuned the strings up a full step to put more tension on it, put the TRC back on and I'll leave it for a few days and see what happens.

PS ... they do not buzz when open, only when fretted the first 4 or 5 frets.

My question is ... if that doesn't help it, what can I do? Any thoughts out there?

Thanks.

 

[Default]

Couple things. Did you put a straight edge on it to verify the back bow? Also, check to see if you have a high fret causing the buzzing. Is this on all strings?

 

[Default]

Also, I would dump the old strings and put on a new set. Always better to start fresh that use dead strings.

 

[Wilmywood]

Couple things. Did you put a straight edge on it to verify the back bow? Also, check to see if you have a high fret causing the buzzing. Is this on all strings?

Not yet, this was right after I got home with it yesterday.
I'll straight edge to check the bow and for a high fret if the buzz is still there after a few days.
I know when I adjust the truss rod on my '72 G37 with the mahogany neck it can take a couple days to really take a new set. Plus, this maple neck is a bit thicker especially toward the body and through the radius where it joins the body, this guitar is noticeably heavier then my '72 G37 with the mahogany neck.
Yes, it is on all 6 strings.
Just looking for ideas to look at next if the heightened tension doesn't help.

Thanks!

PS ... just checked it and the buzz is a bit lessened now, maybe it'll be better in a couple more days.

 

[jedzep]

Sounds like you have good intuition. Looks like very little break angle at the saddle, but hard to tell. If you have what you perceive as a 'back bow', why did you tighten the TR nut? Are you feeling like it needs the dreaded neck job?

 

[Wilmywood]

Sounds like you have good intuition. Looks like very little break angle at the saddle, but hard to tell. If you have what you perceive as a 'back bow', why did you tighten the TR nut? Are you feeling like it needs the dreaded neck job?

Neck job? Who knows. I knew tightening the truss would not improve it but stranger things have happened. I thought it would be foolish to have this issue and not at least try it. For all I knew Guild may have reversed the thread on the truss rod between '72 and '78. It certainly didn't hurt anything to try it.
Remember, I just got this thing yesterday.

What is 'break angle at the saddle'?

 

[jedzep]

The angle of the string coming from the bridge pin hole up to the saddle. If it's less than 15 degrees you're likely losing volume due to low down pressure to the top. A low saddle is just an indication that someone has been sanding it down to lower the action.

If you have a good shop nearby, you'd be amazed at what a setup from square one can do, rather than randomly adjusting out of logical order. Hopefully, you'll be out for under a hundred bucks.

 

[Wilmywood]

The angle of the string coming from the bridge pin hole up to the saddle. If it's less than 15 degrees you're likely losing volume due to low down pressure to the top. A low saddle is just an indication that someone has been sanding it down to lower the action.

If you have a good shop nearby, you'd be amazed at what a setup from square one can do, rather than randomly adjusting out of logical order. Hopefully, you'll be out for under a hundred bucks.

Update: I looked up the saddle break angle and took two photos of it one from each side. What do you think?

PS ... I'm planning on having a bone nut and saddle put on it in the not too distant future.
PPS ... it does not suffer for volume at all

 

[adorshki]

Neck job? Who knows. I knew tightening the truss would not improve it but stranger things have happened. I thought it would be foolish to have this issue and not at least try it. For all I knew Guild may have reversed the thread on the truss rod between '72 and '78. It certainly didn't hurt anything to try it.
Remember, I just got this thing yesterday.

What is 'break angle at the saddle'?

The angle the strings make as they go over he saddle from the pinholes. The taller the saddle, the sharper the break angle.

Within an optimum range of saddle height, break angle will increase the string energy transmitted to the top as saddle height is increased.
Low saddle can be a source of string buzz, assuming the neck is correctly aligned.

Alignment check (not to be confused with checking for twist or bowing): http://www.frets.com/FretsPages/Musician/Guitar/Setup/NeckAngle/neckangle.html

Raising or lowering the saddle lowers the action height accordingly. (It's actually the correct way to adjust action) A saddle may be lowered simply because the owner wanted lower action, but it's also one method of compensating for the beginning of a bad neck angle. So it's a frequent "red flag" to confirm whether the guitar's neck is beginning go out of alignment. But in general that lowers incidence of buzz, it doesn't increase it.

 

[chazmo]

wilmywood,

If you have a good tech or luthier available to you, I'd have this guitar set up properly, as jezdep mentioned. You probably need new saddle and nut, and the neck can be adjusted once those things are done properly.

 

[adorshki]

Update: I looked up the saddle break angle and took two photos of it one from each side. What do you think?

PS ... I'm planning on having a bone nut and saddle put on it in the not too distant future.
PPS ... it does not suffer for volume at all

That looks fairly decent but low side on the treble side. Hard to really tell from the angle of the pic, it should as close to "dead on from the side" as possible. Also can't be sure whether camera itself may be exaggerating the curve of the saddle, known as the profile.
It did remind me however that saddle profile should match the fingerboard radius, that very slight curve it has to facilitate single-note runs.
Mismatched saddle-to-neck-radius profile could also cause buzzing. You do say it's consistent across all strings so the saddle may simply be a bit too low.

BTW I put bone N & S in my D25 and was quite happy with the results.

 

[Wilmywood]

wilmywood,

If you have a good tech or luthier available to you, I'd have this guitar set up properly, as jezdep mentioned. You probably need new saddle and nut, and the neck can be adjusted once those things are done properly.

I do have a good local guy I have used before. If it's not improved by Monday I'll do that. And thank you jezdep.

 

[West R Lee]

As far as "action" which is really relief, this is how I've learned to check it accurately, and it can give you a good idea of an area of the neck potentially causing string buzz.

You simply place a capo on the first fret, and fret the 15th. Then check the distance, provided you have a feeler gauge handy. between the top of the 5th fret and the bottom of the string. That distance should be roughly .005" to '006". From there you can adjust your truss rod accordingly.

What are the factory specifications for acoustic guitar setup?​

String Height (measures top of fret to bottom of string):
Bass-side string height at 12th fret: 3/32"
Treble-side string height at 12th fret: 2/32"

Relief (measures distance from top of fret to bottom of string while fretting the 1st and 15th fret):
Relief at 5th Fret: .005" (a post-it note folded in half is about .005")

We consider these measurements to be a "medium" action height. You should have some room to lower the action from these measurements, but keep in mind that an ultra-low action usually requires lighter playing or adjusted technique to prevent buzzing. Feel free to give us a call if we can be of any help.

Remember that a little bit of tightening or loosening goes a VERY long way, so be gentle. I'll bet the most I've moved a truss rod nut is about 1/8 turn. Also remember to let the neck settle after any adjustment, then check again.

TRUSS ROD LOOSE: When the truss rod is too loose, the neck bows forward. This raises the string height but a slight amount of forward bow can reduce string buzz. Turn the truss rod nut clockwise to counteract this condition.

TRUSS ROD TOO TIGHT: When the truss rod is too tight, the neck bows backward. This lowers the string height and increases string buzz. Turn the truss rod nut counter-clockwise to counteract this condition.

West

 

[jedzep]

Those photos indicate better saddle height than I thought from the top view. That's a good thing. When your tech sets the correct neck relief, the other adjustments will make for the best combination of tone and playing comfort. Have him take a look at the bridge plate under the top to make sure it hasn't been chewed up by sloppy stringing technique.

 

[adorshki]

As far as "action" which is really relief, this is how I've learned to check it accurately, and it can give you a good idea of an area of the neck potentially causing string buzz.

You simply place a capo on the first fret, and fret the 15th. Then check the distance, provided you have a feeler gauge handy. between the top of the 5th fret and the bottom of the string. That distance should be roughly .005" to '006". From there you can adjust your truss rod accordingly.

What are the factory specifications for acoustic guitar setup?​

String Height (measures top of fret to bottom of string):
Bass-side string height at 12th fret: 3/32"
Treble-side string height at 12th fret: 2/32"

Relief (measures distance from top of fret to bottom of string while fretting the 1st and 15th fret):
Relief at 5th Fret: .005" (a post-it note folded in half is about .005")

We consider these measurements to be a "medium" action height. You should have some room to lower the action from these measurements, but keep in mind that an ultra-low action usually requires lighter playing or adjusted technique to prevent buzzing. Feel free to give us a call if we can be of any help.

Remember that a little bit of tightening or loosening goes a VERY long way, so be gentle. I'll bet the most I've moved a truss rod nut is about 1/8 turn. Also remember to let the neck settle after any adjustment, then check again.

TRUSS ROD LOOSE: When the truss rod is too loose, the neck bows forward. This raises the string height but a slight amount of forward bow can reduce string buzz. Turn the truss rod nut clockwise to counteract this condition.

TRUSS ROD TOO TIGHT: When the truss rod is too tight, the neck bows backward. This lowers the string height and increases string buzz. Turn the truss rod nut counter-clockwise to counteract this condition.

West

When I went to Silk'n'Bronze strings on my D25, a significant amount of buzzing set in. The S&B's have a lower string tension than the L350/EJ16 PB lights spec'd for it. It seemed to be localized on the G & B especially when strummed/plucked hard in open chords.

I realized it was possible that my truss, adjusted for the tension of Ej-16's and rarely "tweaked", may in fact be back bowing against the lighter pull of the S&B's. So sure enough after a couple of slightly less than 1/8th loosening turns of the truss (maybe 3/16th total) over 2 days, buzzing was significantly reduced but still present.

I did also examine the frets lots with a magnifier, and alas, there is a bit of crumbling at the fretboard-facing edge of the slots of the culprit strings. But I have a guy in mind when life stops getting in the way.

 

[Rayk]

Update: I looked up the saddle break angle and took two photos of it one from each side. What do you think?

PS ... I'm planning on having a bone nut and saddle put on it in the not too distant future.
PPS ... it does not suffer for volume at all

For me there is no break angle it’s more like speed hump . It looks like the saddle is ramped also ? Not seen that before .

Can we see a few pic’s that shows the neck angle and bow ?

Have you checked humidity levels ?

It doesn’t suffer for volume ? Did you hear it when it was new ? Lol that could go either way just joking

Did you do the straight edge test to show neck angle to the bridge ?

Time for more coffee and honey Err maybe I had too much already .

 

[Wilmywood]

As I said above, if the buzz is not improved by tomorrow afternoon with the truss rod backed off I will take it to my luthier.

I appreciate all the suggestions but correcting this beyond that is above my pay grade.

 

[GardMan]

Do you know what gauge strings are currently installed? Moving to higher tension strings, for example, from lights to mediums or "bluegrass gauge" (medium bass, light trebles) could help correct minor back bow...

 

[Wilmywood]

A few minutes ago I sighted down the neck with the daylight in the background, then took a photo of that view (attached). Looks to me as if the neck, once it gets off the body, dips a bit, then rises slowly toward the nut. The photo seems to verify that observation, a slight 'hump' in the neck around the 15th fret or so. I also ran a 4" long drafting triangle side up the fretboard between the D and G strings and starting at the nut, felt it click lightly as it contacted each fret in order, indicating to me a normal slight bow, but the contact click stopped when I reached the 12th fret as if the neck then plateaus. I wonder if a light dressing of the upper end frets might correct the buzz?

 

[Wilmywood]

Do you know what gauge strings are currently installed? Moving to higher tension strings, for example, from lights to mediums or "bluegrass gauge" (medium bass, light trebles) could help correct minor back bow...

10s, my gauge of choice. It will be set up to accept those with no buzz when I'm done.