Why does this happen when I do a setup?

Antney

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Every month I do a minor setup on my guitar. Installed bone saddle and pins about 6 months ago. I’ve recently shaved about 1/32 or less off the saddle, I have plenty of saddle left. The action is low and comfortable, and the tone is very good, BUT if I back the trussrod off by 1/4 turn the action rises a bit more than I’d like (but I can live with it), but (now here is what I can’t figure out) the tone becomes louder and bell like with incredible overtones and sustain. I know someone will know the science behind this.
 

chazmo

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Interesting that you're hearing something noticeable, Antney. Are you, at normal string height, getting fret buzz or something?

I suspect it's something mundane like loose tuners or perhaps strings not being properly pulled against the pins and/or not properly set in the nut.

Loosening the truss rod (especially just a 1/4-turn) should not have the effect that you're describing unless something is wrong when the tension is set for your proper string height. It's not like you're changing the break angle over the saddle or anything that can even be measured. I am not denying that you hear something, but I can't quite imagine what it is.
 

chazmo

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I had another thought. You said you recently shaved the saddle, but are you:

1. certain that the bottom of the saddle is straight and flat now? If you shaved it poorly, it'll not sit perfectly in the slot. Or,

2. certain that the saddle is properly seated in the slot (assuming 1 is true)?

Neither of these things explain what you're hearing, but if the saddle is moving due to adjustments on the TR, it's possible.
 

GAD

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Every month! Yowsa. I do mine *maybe* once a year unless there's a real need.

Higher actions produce better tone in my experience. There's more room for the string to do its thing without interference from nearby frets. I've known a lot of guys that play with huge strings and high action because they like the tone.
 

Quantum Strummer

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I did a setup on my Taylor a couple years after I got it. Lowered the nut slots and tweaked the trussrod. That was 20 years ago. :) Guess I've had good luck with acoustics…they've all been stable. A couple of my electrics, though, have treated their existence and my ownership of them as a wrestling match.

-Dave-
 

Westerly Wood

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I did a setup on my Taylor a couple years after I got it. Lowered the nut slots and tweaked the trussrod. That was 20 years ago. :) Guess I've had good luck with acoustics…they've all been stable. A couple of my electrics, though, have treated their existence and my ownership of them as a wrestling match.

-Dave-

a 20 year old Taylor? What model? that sounds interesting.
 

Quantum Strummer

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Woody, it's a 1996 512-C Nanci Griffith model. I grab it whenever I want to pretend I'm a fingerpicker. ;) It's got the snappy clarity (mellowed some with time & play) Taylors are known for.

-Dave-
 

adorshki

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BUT if I back the trussrod off by 1/4 turn the action rises a bit more than I’d like (but I can live with it), but (now here is what I can’t figure out) the tone becomes louder and bell like with incredible overtones and sustain. I know someone will know the science behind this.
It sounds like you realize that the truss is actually for adjusting neck straightness and that the slight rise (or lowering as the case may be) in action is only a side-effect or "fringe benefit".
I used to tweak my D25 a couple of times a year, too, and I did notice that when I tried it lower it a taste it lost some sustain.
Here's what I think is going on:
When the neck is given more backbow for flatness, it's actually under more tension and this turns it into a more effective damper for the string vibrations.
Back off the truss a wee bit as you say, and it's not under as much tension and allows more string energy to be dissipated as sound instead of being absorbed into the neck at the nut, or maybe the heelblock, or both.
Here's what made me start thinking about those physics:
A couple of weeks after the D25 had its first refret at about 18 months old, it had what I thought was "the big opening up moment":
I was giving it a warmup-strumming workout when I noticed something special and I thought to myself "Wow this thing has never sounded this good before!" and I could literally feel the neck vibrating in my hand.
I'd never noticed that in a guitar before.
I theorized that somehow the vibrations from the body were getting into the neck and the neck was putting 'em back into the top, through the fretboard extension, maybe?, in some kind of acoustic feedback loop.
And the truss was still set for just a tiny bit of forward-bow for clearance, as part of the step-up from the refret, although I didn't put 2 and 2 together about that until a few years later.

Another possibility is that by backing off 1/4 turn you're lowering the tension on the strings just enough to hit a sweet spot for sustain.
And maybe both.

Anyway, those're my hypotheses and I'm stickin' with 'em until something better comes along.
When I retire I'll have time to really scour the 'net for evidence to support all my pet hypotheses.
:biggrin-new:
 

Nuuska

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. . . Another possibility is that by backing off 1/4 turn you're lowering the tension on the strings just enough to hit a sweet spot for sustain.. . .:biggrin-new:


Howdy

When you release the truss rod - then ( if guitar is laying horizontally ) nut rises a bit, and the distance from nut to saddle changes by ???? - a roadie guess : next to nil !

So if I am right - next to nil - then the tension of strings remains the same.


If I´m not right - and the tension of strings varies - then anybody can do a simple test - tune your guitar up or down or both just a bit - like 1/64th of half-step to see/hear, if there is a "sweet spot" . . .
 

adorshki

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Howdy

When you release the truss rod - then ( if guitar is laying horizontally ) nut rises a bit, and the distance from nut to saddle changes by ???? - a roadie guess : next to nil !
Action at 12th raises (or lowers) by anywhere from about 1/128th to a full 1/64 depending on how much you back off (or tighten), up to a little less than half a full turn, on my D25.
So not nil but there's gotta be some small lowering of tension, not sure how to measure though.
Could be just enough to put it into a "sweet spot" even if less than a pound of tension differential?
I dunno, it just occurred to me as another potential reason for the phenomena.
And maybe not even the tension on the strings themselves but because the top's correspondingly less preloaded?
Forgot all about that.

If I´m not right - and the tension of strings varies - then anybody can do a simple test - tune your guitar up or down or both just a bit - like 1/64th of half-step to see/hear, if there is a "sweet spot" . . .

Simple for you, maybe!
:biggrin-new:
Do they even make a tuner that'll digitally display that small of a frequency variation?
(I ask both seriously and with loving humor)
 

Nuuska

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Action at 12th raises (or lowers) by anywhere from about 1/128th to a full 1/64 depending on how much you back off (or tighten), up to a little less than half a full turn, on my D25.
So not nil but there's gotta be some small lowering of tension, not sure how to measure though.
Could be just enough to put it into a "sweet spot" even if less than a pound of tension differential?
I dunno, it just occurred to me as another potential reason for the phenomena.
And maybe not even the tension on the strings themselves but because the top's correspondingly less preloaded?
Forgot all about that.



Simple for you, maybe!
:biggrin-new:
Do they even make a tuner that'll digitally display that small of a frequency variation?
(I ask both seriously and with loving humor)



Al - My Dear Friend


You did NOT read what I wrote. - "The Distance Between Nut And Saddle"


If you use a precision ANALOG tuner, you will see the difference immediately - not the exact amount, but you will see the pointer is in another position. Slightly off previous position.
And if you think about guitar neck geometry, the up/down movement of i.e. 1/32 inch will affect the action WAY MORE than the distance between nut/saddle.
 

adorshki

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Al - My Dear Friend


You did NOT read what I wrote. - "The Distance Between Nut And Saddle"
No, I didn't mis-read that, but my point was that adjusting the truss (on my D25 at least) produces a measurable change in action height, which means also that there was indeed a change in nut-to-saddle length but probably not as easily measured. (Lengthening one side of a triangle, ie the action height, means that at least one of the other sides (nut to saddle length being the most likely since it's an elastic edge) MUST become correspondingly shorter.
And perhaps even that small difference was enough to put it into the "sweet spot".




If you use a precision ANALOG tuner, you will see the difference immediately - not the exact amount, but you will see the pointer is in another position. Slightly off previous position.
But with analog you're guessing at what freq you're tuning too, if you're trying to create a repeatable experiment.
And if you think about guitar neck geometry, the up/down movement of i.e. 1/32 inch will affect the action WAY MORE than the distance between nut/saddle.
Right but I'm not getting at adjusting the action, I'm just pointing out that adjusting the truss does in fact change action height and only postulating that it might also affect tension.
I don't actually know, and empirically Antney's experience is that adjusting his truss seems to produce a perceptible improvement in tone to his ear.
He asked for possible science behind the phenomena and I'm pointing out physical changes in the instrument that could be responsible.
And I still suspect it's secondary to the neck acting as a better damper at higher tension.
I was just bringing it up for exploration.
So apparently we've got at least one vote against possible lower string tension resulting from the slight change in neck geometry crated by truss adjustment?
Also, the experiment of lowering tension by a microtone to see if "sweet spot" is achieved may be a practical dead end if he's accustomed to playing at concert pitch with companions who may object to his being microtones out of tune.
Antney, are you following us on this?
Antney?
Where'd he go?
:highly_amused:
 
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JohnW63

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I vote for a slightly loose saddle that can be more firmly seated down or against a side of the saddle slot, so that at a higher relief angle it is perfectly snug and transfers the vibrations better without dampening them out.
 

Nuuska

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One wild guess

This idea comes from plate reverbs. The famous EMT plate reverb has a steel plate - about 4x8 feet - that is tightly spring-loaded into rigid steel frame from it´s corners. There is a transducer, that puts the sound into plate, where it reflects from edges. And there are transducers, that pick up the sound. So the plate is simultaneously membrane of a loudspeaker and microphone. Reverb time adjustment is achieved by a parallel wood plate that has felt lining. If we move that plate closer to the metal plate, then reverb time will get shorter.

What if the strings of a guitar ring longer and with more harmonics simply because they are further away from fretboard?

The fretboard reflects strings energy and small part of that reflection hits the strings. When strings are higher the radiation angle gets smaller and distance gets longer - thus lesser back radiation.

A coherent wave level drop is 3dB for doubling of distance. Non coherent wave level drop is 6dB for doubling of distance.
 
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Antney

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Interesting feedback...thanks. I’ve backed off 1/8 of a turn on the trussrod and have a very happy medium with string height, volume and tone. After reading your comments (thank you very much) I deduce what we have here is a minute change in the combination of string length, break angle, and possibly a related change in tension on the saddle that is finding the tonal sweet spot of my guitar. I should have noted my monthly set ups are usually only truss rod adjustment and cleaning the nut, pins, and reseating the saddle. This is the first time in the life of the guitar (25 years) that the saddle has been shaved.
 

adorshki

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What if the strings of a guitar ring longer and with more harmonics simply because they are further away from fretboard?
Can't rule it out completely but I suspect it wouldn't be measurable. I wouldn't believe it unless demonstrated with measurements.

The fretboard reflects strings energy and small part of that reflection hits the strings. When strings are higher the radiation angle gets smaller and distance gets longer - thus lesser back radiation
Not that this refutes your original hypotheses, but isn't it backward? The increased volume is coming from raised not lowered action, and one would suspect that the strings would be louder if closer, if being enhanced by
fretboard reflection.
A coherent wave level drop is 3dB for doubling of distance. Non coherent wave level drop is 6dB for doubling of distance.
Do you mean phase cancellation? That's another area that just occurred to me while I was considering the "fretboard proximity" question.
Oh Antney, we ain't nowhere near done with you yet!
:highly_amused:

Re John W's comment about saddle getting "snugger", I think it's the other way 'round: raising the break angle is effectively making the break angle over the saddle more oblique which would lower the pressure on the saddle.*
That's the whole reason your question seems to run counter to the accepted physics: tighter saddle caused by lower action should be louder.
Only reason for it not to be is that something else got too tight and no longer resonates to max potential: either neck or top.

*It's why a too-low saddle normally lowers volume and sustain: the break angle of the strings isn't sharp enough for max efficiency of energy transfer.
That also gets to the issue of the ideal height of strings over soundboard at the saddle, widely agreed to be about 1" optimum total distance:
I think Nuuska's hypotheses of wave reflection enhancing string volume is probably much more likely at this location than along the fretboard.
 

Nuuska

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Can't rule it out completely but I suspect it wouldn't be measurable. I wouldn't believe it unless demonstrated with measurements.


Not that this refutes your original hypotheses, but isn't it backward? The increased volume is coming from raised not lowered action, and one would suspect that the strings would be louder if closer, if being enhanced by
fretboard reflection.

Do you mean phase cancellation? That's another area that just occurred to me while I was considering the "fretboard proximity" question.
Oh Antney, we ain't nowhere near done with you yet!
:highly_amused:

Re John W's comment about saddle getting "snugger", I think it's the other way 'round: raising the break angle is effectively making the break angle over the saddle more oblique which would lower the pressure on the saddle.*
That's the whole reason your question seems to run counter to the accepted physics: tighter saddle caused by lower action should be louder.
Only reason for it not to be is that something else got too tight and no longer resonates to max potential: either neck or top.

*It's why a too-low saddle normally lowers volume and sustain: the break angle of the strings isn't sharp enough for max efficiency of energy transfer.
That also gets to the issue of the ideal height of strings over soundboard at the saddle, widely agreed to be about 1" optimum total distance:
I think Nuuska's hypotheses of wave reflection enhancing string volume is probably much more likely at this location than along the fretboard.


AHHH - MONDAY - AL IS BACK !!!


What I mean is

- Most of the sound, that we hear, comes from the top of the guitar vibrating.
- Energy to the top comes from strings mostly via saddle & bridge - a small portion via nut & neck.
- I wrote, that if the strings are HIGHER - then the part of energy, that reflects from fretboard back to strings and "fights" the vibration, is smaller - thus lesser interference with strings. And more energy into bridge.

IF it works with EMT plate reverb - why would it not work on smaller scale?
 

adorshki

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- I wrote, that if the strings are HIGHER - then the part of energy, that reflects from fretboard back to strings and "fights" the vibration, is smaller - thus lesser interference with strings. And more energy into bridge.

IF it works with EMT plate reverb - why would it not work on smaller scale?

A-ha!
So you ARE trying to inject the question of phase cancellation into a discussion about the acoustic performance of a mechanically-coupled resonating device.
You sly dog.
:friendly_wink:
 

Nuuska

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A-ha!
So you ARE trying to inject the question of phase cancellation into a discussion about the acoustic performance of a mechanically-coupled resonating device.
You sly dog.
:friendly_wink:


RIGHT !!! :watermelon: :watermelon: :watermelon:

p.s. - is there an emoji with a tail-waggin-dog ?

Like the one on WIN XP search ?


No ? - what about panting dog ????
 
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