zero fret guitar..setting fret clearances

[redir]

Originally Posted by John Arnold

I also do, but for a different reason. The sixth string can have a sympathetic 'back buzz' when the capo is installed. Lifting that one string ever-so-slightly at the nut usually cures it, because the string is no longer contacting the frets when the capo is installed. I have only experienced back buzz in the sixth string.

That's right I forgot about that. I have had that annoying back buzz before.

[donh]

Originally Posted by John Arnold

I also do, but for a different reason. The sixth string can have a sympathetic 'back buzz' when the capo is installed. Lifting that one string ever-so-slightly at the nut usually cures it, because the string is no longer contacting the frets when the capo is installed. I have only experienced back buzz in the sixth string.

The term "neck relief" was invented just to describe the process of curing back buzz. You allow a slight curve to the neck, and the back buzz is gone. This is far less of an intonation trade-off than raising the nut.

The only good reason for raising the nut/zero-fret above the level of the other frets is that the player wants it that way. And if the owner wants it out of tune, then that is what they should get. It is, after all, their instrument.

[Ned Milburn]

Originally Posted by donh

The term "neck relief" was invented just to describe the process of curing back buzz. You allow a slight curve to the neck, and the back buzz is gone. This is far less of an intonation trade-off than raising the nut.

The only good reason for raising the nut/zero-fret above the level of the other frets is that the player wants it that way. And if the owner wants it out of tune, then that is what they should get. It is, after all, their instrument.

Neck relief exists to avoid buzzing due to the travel of the strings. The guitar string vibrates in the shape of a sin-wave, in fact, simultaneously it vibrates as multiple sound waves that exist as the whole string, its half (12th fret harmonic - the octave), 1/3 (7th fret harmonic - octave + a fifth), etcetera. Whether this necessary neck relief helps avoid back buzz is secondary. It will be very difficult to get a guitar set up for its full acoustic volume if it is not set with a slight amount of relief.

Next, open strings do NOT have a soft finger pad pressing the string just behind the pivot (ie: the fret). Open strings also have the advantage of having a greater string break angle over their neck end pivot (the nut) than the break angle over the fret on a fretted note (nearly a 0 degree angle). The finger pressing/holding the nearly 0 degree break angle string over the fret will dampen the string vibration ever so slightly when compared to the open string. This is why open strings often are audibly more "ringy" (in fact, richer in overtones) than fretted notes. So, to help avoid buzzing on the open strings which vibrate slightly more than fretted notes, the nut or zero fret should be set up slightly higher than the other frets.

[charles Tauber]

Originally Posted by donh

The term "neck relief" was invented just to describe the process of curing back buzz.

I don't know who invented the term but I'm pretty sure that it refers to what Ned said.

You allow a slight curve to the neck, and the back buzz is gone.

Adding a slight curve to the neck (i.e. adjusting the truss rod to increase the concave "bow") effectively slightly raises the height of the strings at the nut relative to the first fret. That's the reason that a small adjustment eliminates back buzz.

However, as Ned pointed out, that isn't the purpose of the curvature of the neck: adjusting the height of the nut should be a separate, independent adjustment, for a separate purpose, as John pointed out.

This is far less of an intonation trade-off than raising the nut.

Unless there is a huge bow in the neck, the bow will not have any practical affect on intonation. Raising the nut by literally a few thousandths of an inch, the amount necessary to eliminate back bow, will have minimal affect on intonation.

The only good reason for raising the nut/zero-fret above the level of the other frets is that the player wants it that way. And if the owner wants it out of tune, then that is what they should get. It is, after all, their instrument.

In my opinion and experience, there are some legitimate, practical occasions where raising the nut is appropriate. See above and Ned and John's comments.

[donh]

Ned,

Please read Brian Kimsey's write-up on neck relief. His findings are that less is more, and quite emphatically so. Action at the bridge is the adjustment point for string amplitude, never neck relief. He does agree with you about the nut height being a fix for back-buzz, tho I still demure.

With my guitars, both zero-fret and standard-nut, I have found that when I go for a totally straight neck I tend to get back-buzz. Introducing a couple thousandths of neck relief is what I have found to be useful in fixing the back buzz. I have worked on a few dozen guitars (probably less than a hundred overall, and easily a dozen zero-fret ones with zero fret heights exactly the same as the other frets), and found this process to be useful in every case. Perhaps on the next one . . . . ?

For string clearance to maximise volume, I raise the action at the bridge and adjust intonation to suit.

[charles Tauber]

Here is a picture illustrating the effect of neck relief relative to the height of the strings:



By adding concavity (relief), effectively, the first fret "falls away from" the nut height, effectively increasing the string height at the nut. Doing this is one of the cheap 'n' dirty ways of fixing a nut slot that has been filed a few thousands too deep. (I don't recommend it for optimal setup.)

From: http://www.bryankimsey.com/nuts/nuts3.htm

I'm a firm believer in setting the nut slots at or just a tiny bit above fret height [emphasis mine].

No one disagrees with that.

From: http://www.bryankimsey.com/setup/neck_relief_1.htm

Given the SAME 12th fret action, less neck relief will give equal or greater next fret clearance, equal or greater mid-way action, lower mid-neck action, and lower behind the fret action. The latter could cause some back-buzzes, which might require raising or lowering the nut height. This is the only penalty that I can see for using less neck relief.

I'm puzzled by your conclusions based upon what Mr. Kimsey wrote. Also, his measurements show differences due to amount of neck bow being on the order of a few thousandths of an inch. These are very subtle differences, probably beyond the ability for many players to sense. The question that arises is, "What is the minimum increment that a player is able to feel?" Obviously, it will vary from one player to another. But, it's sort of like intonation. If, for argument sake, the human ear can distinguish pitches that differ by not less than 2 cents, does it matter, practically, if the instrument is more accurate than that? Just because one can measure it does not mean that it is "significant".

If having less bow, reduces the "next fret clearance" by, say, .001", does that matter, practically, to a player - assuming there is no buzzing?

[donh]

Charles,

Please note that Brian said, and you quoted him above " less neck relief will give equal or greater next fret clearance". This is one of the niftier bits of his relief study.

So when you ask "If having less bow, reduces the "next fret clearance" by, say, .001", . . . ." now you are puzzling me. It doesn't move that way.

To answer what you actually asked: I have seen a thousandth make a huge difference and seen it matter not a whit. It all depends upon the other parameter settings, the expectations of the player, and a bit upon the weather. :-)

[charles Tauber]

Interesting. His table provides a set of results after which he states: "Notice that the greater relief does indeed give greater next fret clearance..."

By the bottom of the page, he states the opposite: " less neck relief will give equal or greater next fret clearance..."

Common sense agrees with his actual test results, his first statement.

So when you ask "If having less bow, reduces the "next fret clearance" by, say, .001", . . . ." now you are puzzling me. It doesn't move that way.

Yeah, it does. Look at his table of measurements. It's also what the geometry dictates must be so.