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Chris, thanks!
do you have an easy way to figure out where exactly the G is lying within the nut? The slot is somewhat deep so that I can't really tell just by looking at it? I'll get you the rest if the info a bit later today.
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01-10-2014 08:18 AM
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I unfortunately don't have anything to measure the fretboard length accurately. However, I did the other measurements:
6: A bit higher than paper
5: A bit lower than 6 but paper still fits under
4: touching the fret
3: touching the fret
2: ever so slightly touching the fret
1: about the same as 6
This is what the compensated bridge looks like. Not at all what I would call a usual pattern. Also, when I had used the TOM, the upper frets were good but the intonation on the lower ones was then off.
For some reason the image upload doesn't work. But here it is:
https://dl.dropboxusercontent.com/u/...%2035%2031.jpg
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Hi Alain,
Thanks for the info. Note that is the sort of stuff that would be a bit faster to check on a workbench, but we are going all cyber here, so a bit slower progress.
And to tediously mention again:
While I have done this sort of thing since Jimmy Carter was president, it is still not the same as a tech/luthier having your guitar in-hand. So if he says something that disagrees with me, go with the in-person person. In my opinion.
OK,...
>>> do you have an easy way to figure out where exactly the G is lying within the nut?
No easy way. I typically look closely with a sort of watchmaker thing I stick on some glasses, then put a file in the slot to feel the slope of the slot.
When in doubt, I fill the slot and re-cut it. Filling with bone dust (saying "fee-fi-fo-fum" makes the awful smell of making bone dust a bit easier) and good thin CA works great.
In my opinion, all slots should be low enough so that the string is at fret height. I keep filing (slowly and in small steps) so that I can not really see a gap above the first fret, but I can hear it in two ways:
1. As you tap down on the string above the first fret (while fretting between the 2nd and 3rd) you can hear it come in contact with the first fret.
2. When (still fretting between the 2nd and 3rd) you pluck the string over the first fret you can hear that the full distance from the second fret to the nut is weakly vibrating for a very short time.
In my opinion, a paper thickness of clearance is worth getting lowered to as close the the first fret as possible, again when fretting between the 2nd and 3rd.
On the t-o-m pic, can you clarify how the bridge is oriented. Are we looking at the low E on the left, which is how this bridge is typically oriented?
If so, then the saddle pattern is rather in a normal range of adjustment with no extraordinary G string position as you mentioned earlier being cut into a wooden bridge. Have I missed something in your comments, which do not quite line up in what passes for my brain (the G being deeply compensated on one bridge, but in a fairly normal position on the t-o-m pic).
>>> Also, when I had used the TOM, the upper frets were good but the intonation on the lower ones was then off.
I understand. This is a sign that the nut slots need work, or that the nut is not in the most ideal position.
Were the low position notes sharp or flat when the upper position notes were at their best with the t-o-m?
>>> I unfortunately don't have anything to measure the fretboard length accurately.
Even a basic ruler will do if you look very carefully. Also, metric numbers are fine. While the nut position is extremely likely to be very accurate on this fine guitar, it is worth a quick check if at all possible. I have run into a very, very few surprising situations.
Do you have any practical way to get the nut slots uniformly set to just barely (very hard to see) above the first fret when fretting between the 2nd and 3rd frets?
Please clarify the apparent difference between the G bridge position as filed by your luthier vs. the position on the t-o-m. Thanks.
And if you can stand the boredom, I'll recycle some old text on intonation and compensation in a post right after this.
Chris
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NOTE: This is a long dull post. Please pass it over if the dreary details are of limited interest.
************************************************** ************************
OK, so first bridge compensation:
When you tune up a string it follows a mostly straight path from the nut to the bridge. Yes there is a slight sag due to gravity in playing position, and a slight upward bow at the bridge and nut, particularly on new strings. There are also some very minor magnetic effects. But for all practical purposes the string is straight.
To play a note we need to press the string down to a fret. This means that the string is no longer on its straight path. So we have lengthened the path of the string and thus pulled the string to a higher tension, resulting in a sharp note. This is a problem.
Now when playing at the first fret we only press the string a short distance, but farther up the FB this distance, and resulting sharpness, increases.
We deal with this by moving the bridge saddle back.
To see what this does,...
If for example, we move the high E saddle back 1,5 mm (1/16"), this means that we have lengthened a 25" scale guitar's string length by 1/400th (0.25%). No big deal and we re-tune slightly back to E.
Now if we play at the first fret. Our absolute 1,5 mm (1/16") extension of the string is now a larger % of the total vibrating length. It is now (roughly) 1/376.5 (0.265%). So this compensation would make the string flat compared to the open string EXCEPT that we are stretching the string slightly to play the F.
Now lets play the 12th fret E. The 1,5 mm (1/16") extension is now 1/200 (0.5%) of the vibrating length of the string, so will make the note flatter still, but the distance we stretch the string to play the 12th fret E has also grown.
Now, the proportion of increased stretch as we play up the FB does not exactly match the increase % of the absolute 1,5 mm (1/16") compensation. But in most cases it is close enough. Life goes on; music is played.
BUT,...
In fact when a string is played, it is stretched in up to four (arguably more than four) different ways.
The stretch to get a string to a fret is, however, the big one. And bridge compensation is in most cases good enough.
There are exceptions, and it may be interesting to see how those exceptions happen and what is done about it.
*******************************
And more in the following post.
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NOTE: This is another long dull post. Please pass it over if the dreary details are of limited interest.
************************************************** ***
More on bridge compensation:
When you play, the string stretches. The core of a wound string stretches along its length - a very efficient way to increase tension.
The windings on a wound string are also stretched, but this stretch is in effect pulling the winding apart slightly. The effect of this on the tension of the string as a whole is so little that we can for all practical purposes ignore this winding stretch.
So, bridge compensation distance within a given string set usually varies based more on the size of the string core, not as much on the overall gauge of the string.
The low E core is larger than the high E core (which is also the whole diameter of the high E string). And sure enough, we compensate the low E about 3X as much as the high E.
When using a t-o-m bridge, or carving a wooden bridge by hand, we can we also compensate a plain G far more than a wound G, which has a rather small core.
We can also compensate a B more than a wound G and less than a plain G. Ignore the string gauge, look at the core size and it all makes some sense.
In practice, with string gauges above .012 to .050 or so, and with a WOUND G - the variation from string to string is really not all that far from a linear increase as we go from high E to low E. So a simple angled (but otherwise straight) bridge is close enough for many players.
With lighter strings, a plain G, or for players who find that they experience the actual slight difference - it can be worthwhile to compensate each string individually.
But please consider:
- Making a bridge "perfect" for a given set of strings on a given day, WITH A GIVEN PLAYER'S GRIP is all well and good. But this moment of presumed perfection will not last as the strings age, and as new strings vary slightly in gauge and consistency of diameter and shape.
And even more to follow,...
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NOTE: This is yet another long dull post. Please pass it over if the dreary details are of limited interest.
************************************************** ***
OK, so four types of string stretch (which goof up intonation):
There have been a few attempts to name the types of string stretch, but unless I was writing a book on the subject I think I'll just number them.
Remember - strings follow a reasonably straight path from the nut to the bridge. If we alter this path, we lengthen it which increases string tension and raises the pitch of a note.
Stretch #1:
When we press a string down to make contact with a fret we stretch it. This raises the pitch. As we play farther up the FB we press the string farther to reach the fret. So the farther up the FB you play the sharper notes will get.
A given amount of bridge compensation becomes a larger % of the vibrating string length as you play farther up the FB. So the effect of bridge compensation increases as you play farther up the FB, which makes it quite effective in compensating for Stretch #1.
Stretch #1 is the most significant of the stretches. So only compensating for this is sufficient for most players on most guitars.
Stretch #2:
If #1 is the most important, then Stretch #2 is the stupidest and most unnecessary. It is unfortunately also VERY common. You should never have Stretch #2.
In principle, the nut should be at the same height as the frets. There are in fact some exceptions to this, but they are so small or obscure that for all practical purposes - THE NUT SHOULD BE AT THE SAME HEIGHT AS THE FRETS.
Sort of. But for now please accept this idea. We can get to the minor variations later if anyone wants to.
In a typical factory, it is seemingly not practical to get the nut slots down at fret height. You do not know what strings the player will use, and it is time consuming to get a nut cut correctly.
So nuts are typically made too high for two likely reasons:
- It is easier to later lower them that to raise them.
- Too high does not make for a loud cowboy chord buzz that kills a sale at GC.
But if a nut is too high you get Stretch #2 ("The Devil's Stretch").
If the nut is the same height as the frets, then you have a simple linear change in distance from the straight string path to the fret as you play up the FB. (Ignore neck relief for now.)
You have, in effect, zero stretch on an open string, the progressively increased stretch as you play higher frets.
BUT, if the nut is too high, you get a stretch not only down from the raised bridge to the fret crown, but also down from the raised nut. This may not sound all that bad as an idea, but here is the tricky and evil part:
The added stretch from a raised nut is GREATEST at the first fret, then becomes less of a factor as you play up the FB. It works exactly the opposite of Stretch #1 in terms of progressive increase. It is NOT able to be corrected by bridge compensation.
But wait a minute - doesn't the inverse nature of Stretch #2 balance out Stretch #1?
Not really. Yes the progressions of the effect of the stretches are opposite, but both make the string play sharp. One stretch does not cancel out the other at all.
AND, a high nut makes low position playing quite difficult. It also makes the overall action higher while providing no added buzz-reducing fret clearance toward the bridge.
In my view, you should never have Stretch #2. In practice, it is really more accurate to recommend that you should never, ever have a degree of Stretch #2 that has any practical effect on intonation.
And still even more,...
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NOTE: This is short, but still a dull post. Please pass it over if the dreary details are of limited interest.
************************************************** ***
Stretch #3 is easy to describe (so a nice break).
Stretch #3 comes from lateral movement of the string along the fret. It is how we bend notes.
Unfortunately, we also get some lateral movement when we do not want it.
For rock/blues players with very light strings, you can sometimes help by adding a bit more bridge compensation than might seem ideal. The idea is that the compensation will help with stray sharp notes in chords, even though strings can get a little flat way up the FB.
However, for rock/blues style solos, it is pretty easy for most advanced players to "naturally" add little left-hand squeezes and bends in solos to hit the notes as they wish way up the FB.
It works better than it sounds in writing.
For jazz players, the answer is practice (nothing new there,...) to avoid accidental lateral movement, particularly in tricky chord shapes. Fortunately, relatively heavier strings help as well.
And so on to the interesting Stretch #4 and the world of nut compensation,...
And another post,...
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NOTE: This is yet another long dull post. Please pass it over if the dreary details are of limited interest.
************************************************** ***
And Stretch #4:
We press strings down to make contact with the frets. But we do not stop at the exact moment that we contact the frets. We press the strings down PAST the tops of the fret crowns to various degrees.
We all do it.
It is unavoidable.
This hyper-extension of the string past the fret crown adds further stretch. This added stretch is #4.
It varies VERY widely from player to player, and it varies as we play up the FB.
Like all stretches, it makes notes sharp.
For most players the effect is strongest down by the nut.
The lower fret positions leave a greater span of string between frets. This is no big news. But it means that a given finger pressure will move the string deeper past the fret crowns at the second fret than it will at the 15th.
Some players play right up just behind the frets, others press more in the middle between frets. This matters.
IN GENERAL:
Stretch #4 is a bigger factor in low playing positions and has far less effect as we play up the FB. This is because it is simply much harder to press the string past the fret crowns and down toward the FB when the span between frets is shorter.
Stretch #4 is corrected, when needed, by NUT COMPENSATION. You move the nut forward toward the bridge. This compensates for the sharpness caused by Stretch #4, and works most effectively in low positions. The "ideal" amount of nut compensation varies for each string. Nut compensation has less effect as you play farther up the FB.
Higher frets, lighter strings, and heavy left hand technique all contribute to stretch #4.
It makes perfect sense that some players will find a compensated nut to be a miracle of intonation improvement, while others will say it makes no difference. They can both be absolutely right based on their specific circumstances.
Compensated nuts are nothing new. I sneak nuts forward about 0.5mm. This is not really a careful compensation, but for me it results is noticeably better overall intonation as I have gone to higher frets over the years.
Adding small shims in front of the nut at the B string (effectively moving the nut forward for the B string) is an old trick to solve low position intonation troubles for cowboy chord strummers who are very strong.
The Feiten and Earvana systems offer a compensated nut. They both have their problems in my opinion.
The Feiten system is a set of nut compensation and bridge compensation offsets. It is heavily marketed in what one may find to be an irritating manner. There is no magic here. I do not wish to argue with anyone who has found the Buzz experience to have improved the quality of their lives.
The Feiten product and process (via a trained Feiten installer) adds a set of nut compensations that are better than nothing for some players, and a set of "intonation" offsets that attempt to address the fairly classic, and more often noticed artifacts of guitar intonation "errors". In my opinion, a luthier who understands nut compensation can do a better job (and without the dopey BS) if you have low position intonation troubles.
The Earvana is, in my opinion, a more honest approach and presentation of a compensated nut. The one problem, and it is a BIG one in my opinion, is that the Earvana sort of groups Stretch #2 and #4 together and claims to fix them both. And indeed it does improve them both.
But in a way the Earvana description and approach encourages sloppy set ups. Again, a luthier who understands nut compensation can do a better job - even if just by adapting an Earvana for a better basic setup followed by nut compensation.
OK, that should be enough to put anyone to sleep, or better yet back to playing the guitar as I will now do.
Chris
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I love this shit ptc !
keep it coming
I sooo wish you were local to me
I would ask you to lower my nuts for me
(my nut just feels high but i'm too scared to do it in case i go too far !)
I don't have any big intonation probs but the mechanics
of the strings behaviour is facinating to me
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I'm all for moving nut forward.
I can't but remember a friend of mine and some semi acoustic Italian guitar of his. It had the 0 fret by design, but he did not like the looks of it, so he forced the sucker out. I was without a guitar at the time, but somehow we still made an album worth of it, and a place in Stadelijk Museum A'dam, for an exhibition.
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Originally Posted by pingu
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Hi Pingu,
Hope all is well with you.
>>> I love this shit ptc !
>>> keep it coming
Most of that was old text recycled since it is sort of related to the whole thread I suppose.
So I do not deserve credit for cranking out the words on the fly.
Also, there are alternate views on this that others may have.
Chris
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One nut hung low. Yeah, riiiiight, I get that a lot in Midwestern bars from hirsute troglodytes who should know a lot better........ Originally Posted by pingu
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Chris, amazing information! Thanks so much for posting. I have searched far and wide to no avail for good explanations of this stuff.
Ok, that said, I just got back from my Luthier. He's keeping the guitar for the week because he couldn't figure it out off hand. He doesn't think there's anything wrong with the nut but can't explain the intonation issue otherwise. He measured the frets and said they seem perfect. The very slight difference in string heights at the nut is within normal tolerance (says he).
Chris, yes you were right, the TOM was photographed as you would be looking at it on the guitar (i.e. bottom is the 6th string). Comparing that pattern to the original Sadowsky bridge, it is not that far off.
>>>Were the low position notes sharp or flat when the upper position notes were at their best with the t-o-m?
I believe they were sharp but I can't remember exactly.
>>>Please clarify the apparent difference between the G bridge position as filed by your luthier vs. the position on the t-o-m.
The G on the TOM is a few mms further back. My Luthier couldn't get the true tone bridge filed back that far because it was already hitting the gap on the other side. With his filing the G was still about 5 or 6 cents off at the 12th fret.
Anyways, he does really know what he is doing and he himself is stumped at this point so I think this is not such an easy case. I am very curious as to what he will come up with. He did mention that he might need to move the nut slightly forward but he has worked on my Gibsons and said that the craftmanship and precision on the Sadowsky is far better so it would surprise him if that makes the difference.
He has written alot of material on the subject and is really a fine luthier:
www.gropius.de
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Hi Alain,
>>> I have searched far and wide to no avail for good explanations of this stuff.
This stuff is all pretty much extremely basic "Newtonian" physics in my opinion, but in the musical community it does seem remarkably difficult to find much that is not filtered by product marketing, or significant "dumbing down" presumably to appeal to some perception of a musician's level of interest.
Others may feel quite differently on the subject.
>>> [My luthier says] The very slight difference in string heights at the nut is within normal tolerance
I agree that it is within normal tolerance. I am not a fan of normal tolerance at the nut. While I am very much an average-speed worker, it takes me about 10 minutes to get the strings to a very accurate height at the nut vs. a more typical and very reasonable tolerance. In my opinion this is a very valuable 10 minutes for both playability and intonation.
But I think that the majority of tech/luthiers have a different set of priorities, and they seem to do just fine.
>>> Anyways, he does really know what he is doing
I am definite sure of that, and yet again suggest that you take his guitar-in-hand opinion over my web-forum opinion.
>>> and he himself is stumped at this point so I think this is not such an easy case.
I understand. And in such a situation I like to gather as much info as possible (thanks for that), then look for anything that may be a factor, even when within a normal tolerance that one sees day to day on guitars.
Considering everything in that has come up, I'd start at the nut - get it to a much tighter tolerance - then see were things stand.
I think it is British writer George Macdonald Fraser who said that the most expressive sentence in the "American" language is, "Uh-huh".
>>> >>> He did mention that he might need to move the nut slightly forward
Uh-huh.
Or less obnoxiously put:
This is certainly one of the things that your guy may conclude when he gets the guitar on his bench. And in my opinion, the ideal place for an uncompensated nut is slightly forward of the calculated "zero" location on the scale.
Almost interestingly, LMI supplies their slotted FB's with a zero fret slot. So the "zero" location on the scale is in the center of this slot. When you cut off this end of the FB to build a guitar, removing the whole zero fret slot, the end of the FB is slightly too far forward.
Hilariously enough, it is pretty much the same distance as I like to sneak the nut forward for noticeably better intonation in an uncompensated nut.
LMI are very much aware of this slot position and what happens when people use their slotted FB stock.
>>> he has worked on my Gibsons and said that the craftmanship and precision on the Sadowsky is far better
While I have not seen you guitar, I certainly agree with the general sentiment.
Please can you let us know what ends up happening? It would be great to follow up on the final results.
Chris
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I looked at the website for your luthier. He certainly thinks through the subject of intonation far more than most luthiers, which can only be good news for you.
Thanks for the link.
Chris
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And in general:
Despite the absurdly long and dull posts I made above, I am leaving out a few things. One of which is the stiffness of the strings, as Alain's luthier mentions (although with significantly different emphasis that I have noticed in practice).
This stiffness is an unfortunately long topic to really cover well, and in my opinion (and measurements) is almost entirely compensated by bridge compensation until you get up toward the 17th fret (the varies depending on the gauge and type of string).
All in my opinion.
Chris
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Thanks Chris, your information is really invaluable. Yes, I will definitely let you know how it works out!
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He even has a little book in his workshop that he wrote on the subject. So, he has really put a lot of thought into it. I'm confident that he'll be able to figure it out. Originally Posted by PTChristopher2
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Just tried it on my oddball acoustic, a Wechter Pathmaker double cutaway. I'm using daddario nickel rounds and tuning has been iffy. So I gave up on clip on tuners and free apps and bought the Peterson Strobo soft iPhone app, set it to "show whole cents" and was immediately impressed by the Taylor offsets. Gonna try it on my Tele and Ukulele as well...
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Chris, I just got the guitar back yesterday. I actually worked with my luthier for about an hour to try and figure out what was going on. Well, we never really figured it out but what we did was take the sadowsky true tone and then adjusted it further to compensate for the 12th fret discrepancies I mentioned above. He was convinced that there is nothing wrong with the nut. After compensating the bridge, the intonation is very good. The pattern looks a lot like the TOM I had compensated but sounds much better due to the original wood. I don't know if it's my imagination but I'm confused because with the TOM, the intonation on the lower frets was off. It now seems well balanced across the neck with only the discrepancies that are normal with any guitar. For now I'm a happy camper and the guitar sounds fabulous. Let's wait and see how my ears adjust to this. I've been known to start to notice slight offness after a couple of days :-)
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Ha, I'm so glad I did not come out as complete fool bact hen when I said ...
Originally Posted by Vladan
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Alain,
Thanks for following up.
I sounds like all is going very well at this point.
If your lower frets end up sharp when the notes around the 12th are OK, then this generally means a nut that is too high, too far back, or with slots that drop away at the front edge (same as too far back really).
I'm glad the bridge worked out. Some find the so called Nashville t-o-m to be a little glassy sounding, while wood is a great match for your guitar (in my opinion).
Thanks again.
Chris
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Thanks Chris. I appreciate all your help with this. I will follow up one last time once I've had a chance to really play it in. I played pretty much he whole day today and didn't have to retune once. That's a good sign.
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Sounds great Alain. No need for more follow up for my sake. Glad it all worked out for you.
Chris
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