Interesting neck relief observation

arwhite · #1 11-17-2020, 08:57 AM

I have a Taylor 150e 12 string. Big sounding guitar. Fun to play. One thing I have noticed with it is there is a point as I reduce the neck relief that the tone of the guitar seems to just disappear. I'm eyeballing the relief so don't have an actual measurement, but it's not so flat that strings are buzzing. There is noticeable relief in the neck. When I get to that point with it and back it off not even 1/8th of a turn the tone comes back. When I say the tone disappears I mean it just sounds flat and dead with no bloom to the notes.

It's the oddest thing. The setup is good on the guitar. It has done it regardless of the brand of strings on the guitar. It's not really a problem that needs addressing. It's just interesting to me how there is this tone cliff related to the neck relief. I've never experienced this on any other guitar I've owned. I've had guitars that had a neck relief sweet spot, but not like this.

I'm curious if others have ever run across something similar?

RoyBoy · #2 11-17-2020, 09:10 AM

Yes, I noticed it first on mandolins I was setting up. It's also why bluegrass players keep their action high (they need to be loud to put up with banjos)

soma5 · #3 11-17-2020, 10:57 AM

I have noticed this also. Another further thing I've noticed is that most times, if you just leave the guitar alone for a while (a day or two) then the tone comes back. I suspect that the neck regains some of the relief you removed when you tightened the truss rod.

redir · #4 11-17-2020, 10:59 AM

Some very accomplished luthiers swear that tension in the neck has something to do with tone so you could be experiencing that. I cannot say in my 25 years of building and repairing I have ever seen it. I don't claim to be 'accomplished' but still. If it does happen it's rare and you could be experiencing that though sort of in reverse as you are lessening the tension.

It could also be as mentioned above that when you adjust for less relieve you are also lowering the action on the fretboard. Lower action means more string contact with the frets even if it's not a buzz or perceptible by ear if the string barely touches the fret in front of it then it saps the energy out of it. An easy test in that case would be to first measure your action prior to adjusting the relief at the 12th fret, adjust the relieve then raise the saddle to achieve the same action and test for the tone.

Rudy4 · #5 11-17-2020, 03:54 PM

Think about the neck in a way that considers the area removed to house the truss rod. This material that was removed contributed to the neck's natural resonance and rigidity. There's a small "neutral point" for the truss rod where it doesn't exert any tension on the neck, and that point can have an effect on the instrument's produced sound, and the resulting change in sound can be good or bad.

A small amount of truss rod tension in either direction can change that "neutral tension" tone. Again, for the better or worse.

If you get what you want tone-wise at a truss rod tension that gives you your desired amount of relief then you can be a happy camper.

Robin, Wales · #6 11-17-2020, 04:37 PM

Having played around a lot with old mountain dulcimers and built a few, plus spending years setting up resophonic guitars (adjusting props etc) I would say that this phenomena has something to do with the truss rod having a solid contact with the neck and fretboard - in some form.

For example: A loose brace can really deaden the tone of an instrument and gluing it down firmly again will bring the instrument back to life. Or take an old dulcimer and hold it up in the air and it is fairly quite but play it on a wooden table top and the whole room will be dancing. Or on a reso guitar getting solid contact between the cone and biscuit will be the difference between a lush sound or a banjo!!!!

If you imagine the truss rod flexing in the neck, then the pressure it exerts on different parts of the neck and fretboard will change as you adjust it. On some guitars there could well be a dead spot (sort of loose brace syndrome) where the vibrations from the nut or frets (if the string is fretted) are not transferred to the body of the guitar quite as effectively. On a double action truss rod this may be at its neutral point.

Anyway, I think it is something to do with a change in the vibration transfer properties of the neck.

Mr. Jelly · #7 11-17-2020, 07:20 PM

Robin sounds correct. So I agree with his thinking. My story isn't to disagree with his post. I just had a new saddle installed on my D-1A. I did it to raise the action to get a little better sustain and sound from the high strings. It was all correct before the modification but I was like it was bottoming out at times. I raised the e string by .02. There was no buzz or any noticeable problem. It just seemed like it was constricted and it could be better. And it is. Not all string constriction buzzes.

dnottis · #8 12-09-2020, 02:30 PM

Quote:

Originally Posted by arwhite

I have a Taylor 150e 12 string. Big sounding guitar. Fun to play. One thing I have noticed with it is there is a point as I reduce the neck relief that the tone of the guitar seems to just disappear. I'm eyeballing the relief so don't have an actual measurement, but it's not so flat that strings are buzzing. There is noticeable relief in the neck. When I get to that point with it and back it off not even 1/8th of a turn the tone comes back. When I say the tone disappears I mean it just sounds flat and dead with no bloom to the notes.

It's the oddest thing. The setup is good on the guitar. It has done it regardless of the brand of strings on the guitar. It's not really a problem that needs addressing. It's just interesting to me how there is this tone cliff related to the neck relief. I've never experienced this on any other guitar I've owned. I've had guitars that had a neck relief sweet spot, but not like this.

I'm curious if others have ever run across something similar?

I just started a thread about this same thing. I found .008 to give the best tone across multiple acoustic guitars. I have found i can take the action really low as long as the relief is at least .008 and they will sound great. I can't tell you how many guitars I sold or returned because they sounded thin at .004" relief...

https://www.acousticguitarforum.com/...d.php?t=600305

Alan Carruth · #9 12-09-2020, 06:26 PM

One of my students came back a few weeks after he'd finished his second guitar with a problem. When first set up it sounded great, but later it lost a lot of it's 'brightness' and sustain. There dd not seem to be any high fret issues, but after some other things failed to solve it we tried a light fret dressing. Sure enough, there were some high spots; not enough to cause the ruler to rock, but definitely there. The high spots were not enough to buzz, but they did choke the strings a little. At the time we were using a small bead of glue in the fret slots to make sure they were secure, and I wondered if the pressure of the strings and tightening the truss rod had caused the glue to pop up the frets a little. We stopped using glue in the slots after that, and have had no more of those problems.