Question for Muttley or Light: String Break Angle @ Bridge

  • Thread starter Thread starter Zaphod B
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Zaphod B

Zaphod B

Raccoons-Be-Gone, Inc.
Hey, Muttley and / or Light -

This question applies to my new Gibson LP. Is there an optimum break angle for the strings as they cross over the bridge to the tailpiece? My tailpiece, as it left the Gibson factory, is not screwed down all the way to the body - in fact, it's about 1/4" (maybe slightly more) off the body.

The break angle seems adequate just to look at it, but should I just screw the tailpiece all the way down? :confused: Or does it really matter?
 
Break angle doesn't change much, as long as there is enough of it. If not, then there is not enough downward pressure to keep the string in place, and you can get buzzing.


Personally, I like stop tailpieces to be as low as they can go without the strings touching the back edge of the bridge.


Light

"Cowards can never be moral."
M.K. Gandhi
 
exactly

i agree w/ light on this ..... i just did one about 10 mins ago ........ a brand new les paul standard ..... it has some buzzing ...... i leveled and polished the fretts ..... after checking the neck relief .... and adjusting the truss rod .... i let it sit over night ... this am i did the fretts .... re strung it .... plays great now .... low fast smooth action ..... i set the tail peice as close to the body as i could w/ out the strings hitting the back of the bridge ...
 
As I understand the physics of it, as you lower the tailpiece you increase it's mechanical coupling to the guitar body. By rights this should result in increased sustain. In my experience I have never been able to tell the difference on any guitar I worked on. Some customers claimed they could. This would be because any vibration beyond the saddle can have a dampening effect at the bridge. The difference is negligible at best.

The downside is that an increase in break angle is an increase in stress at the point the string crosses the saddle. In extreme cases you may have more string breakage.

I tend to set them up just like Light suggested.

One further note: If you decide to adjust your stop tailpiece, at least remove all the tension from the strings and use a quarter to turn the studs. A screwdriver will chew up the slots every time. They make a wrench to do this.

Muttley, I will take my beating now
 
i agree w/ light on this ..... i just did one about 10 mins ago ........ a brand new les paul standard ..... it has some buzzing ...... i leveled and polished the fretts ..... after checking the neck relief .... and adjusting the truss rod .... i let it sit over night ... this am i did the fretts .... re strung it .... plays great now .... low fast smooth action ..... i set the tail peice as close to the body as i could w/ out the strings hitting the back of the bridge ...

LOL! You had to do that to a brand new Paul to get it to play like a brand new Carvin???? :p :p :p :p :p
 
yep

yep ..... sad ..... he took it back where he bought it .... they raised the bridge to stop the buzzing ..... he brought it to me and asked me to help .... i said are you sure you want to do this ..... he said please do it ..... now it plays great w/ no buzzing anywhere
 
hang me ?

im sure light will hang me on this ......... i told him to contact gibson ..... he wanted it done now ...... i waited 3 days before i touched it .... just to give him time to think it over ..... should not have to do that mutch work on a new guitar
 
As I understand the physics of it, as you lower the tailpiece you increase it's mechanical coupling to the guitar body. By rights this should result in increased sustain. In my experience I have never been able to tell the difference on any guitar I worked on. Some customers claimed they could. This would be because any vibration beyond the saddle can have a dampening effect at the bridge. The difference is negligible at best.

The downside is that an increase in break angle is an increase in stress at the point the string crosses the saddle. In extreme cases you may have more string breakage.

I tend to set them up just like Light suggested.

One further note: If you decide to adjust your stop tailpiece, at least remove all the tension from the strings and use a quarter to turn the studs. A screwdriver will chew up the slots every time. They make a wrench to do this.

Muttley, I will take my beating now

hehe, no beating or otherwise yout understanding is sound I guess but one of your conclusions is not right. I'll try and help you think about it some more..:)

Lets just have a look at what goes on in mechanical and physical terms around the bridge. It will give us an understanding of what we should expect, then we can see if our experience backs it up.

First if you have buzzing due to too little break angle you need to increase the break. What you effectively have in that situation is a string that is not anchored correctly and therefore a longer string length than you should have. There should be a point on the saddle at which the string is "fixed" and it forms a "node of vibration, ditto the nut. I can elaborate on the manner in which the string behind the bridge behaves if anyone wants but now for the sake of argument ignore it acoustically because for our purpose it is irrelevant.

The string behind the bridge is more important when you consider the way it imparts a downward force through the bridge. What you have is pretty much the same as the force in a bow and arrow type arrangement. The more the string is drawn back the greater the force. On a guitar this force is static and wants to push the bridge down. The bridge resists the force. You can calculate the force and if anyone wants it I can post the formula.

You say you expect the coupling of the two to be increased if the downward force is increased that is correct. Have another think about what dictates sustain/decay and volume/amplitude as the two are linked. When the string is plucked a given amount of energy is put into the string. That energy gives us our amplitude and decay, as the string vibrates you can only have a certain amount of one or the other, more sustain equals less volume and vice versa. As the string loses energy the amplitude drops and the vibration decays. The energy is lost in several ways but in this example the most important is the energy lost via the bridge and the nut. With a higher break angle the energy in the string is encouraged to leave via the bridge faster than it would if the break angle were less. This results in LESS sustain as the energy is lost faster. Thats the theory and what actually happens.

How does it effect the tone or note produced. Well as most have stated it has less effect on an electric. The reason for this is that the note is being produced as a result of the pickup detecting the movement in the string and converting it into an electrical signal. Also a lot more of the strings ebergy is reflected back down the string as on a n acoustic it is encouraged to move the soundboard. The relationship between the strings vibration and the electrical signal is more forgiving than the way an acoustic handles the transfer of energy, but the sustain will be less the greater the break angle.

An acoustic or archtop converts the strings energy differently. The energy in the string that leaves the bridge makes the soundboard vibrate and it is this that amplifies the sound. So the greater the break angle once again the greater the initial amplitude or volume and the faster the decay. On an archtop this has a marked effect.

Violin family instruments are different in one distinct way. Despite sharing exactly the same mechanics and physics in terms of the string and the break angle. The energy that is being put into the string is a constant supply from the bow rather than a finite amount from a pick. This is why soundposts work in violins, they couple the front and back and allow the energy to pass faster and further around the instrument. That also explains why they are not really a good idea on plucked instruments and not used on archtop guitars.

You can see why I ignored the string behind the bridge now can't you. This post is far too long already...;)

Oh and if your breaking strings at the saddle you need to make sure it is clean and allows the string to move over it smoothly just the same as a nut slot. The difference of a few degrees break angle will not kink or work harden the string excessively so it shouldn't be a problem. Look for rough or burred edges instead.
 
I apologize to Zaphod if this is highjacking his post.

Muttley, there is something missing in my understanding. Lets take the same Les Paul we have been discussing and replace the stop tailpiece with a Bigsby. My experience tells me there will be a detectable loss of sustain even if the break angle and such are essentially maintained. I had always assumed that this was because the spring in the Bigsby allowed the string to expend mechanical energy beyond the saddle That energy would represent a portion of the total energy of the vibrating string. The bridge doesn't completely decouple the string on either side. A loss of sustain results.

I was thinking the same thing happens with a stop tailpiece to an infinitely lesser extent.
 
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I apologize to Zaphod if this is highjacking his post.

Muttley, there is something missing in my understanding. Lets take the same Les Paul we have been discussing and replace the stop tailpiece with a Bigsby. My experience tells me there will be a detectable loss of sustain even if the break angle and such are essentially maintained. I had always assumed that this was because the spring in the Bigsby allowed the string to expend mechanical energy beyond the saddle That energy would represent a portion of the total energy of the vibrating string. The bridge doesn't completely decouple the string on either side. A loss of sustain results.

I was thinking the same thing happens with a stop tailpiece to an infinitely lesser extent.
Yes both in theory and practice some energy travels down the string beyond the bridge. That is one way that energy is lost, most of it will return down the string from where it came (if it didn't we wouldn't have a vibrating string) or into the body of the instrument.. The energy in that part of the string in simple terms behaves the same as energy in the other part of the string. This is sympathetic vibration and is the cause of wolftones in many bowed instruments, remember bowed instruments have a constant supply of energy. The violin world has declared that there is a preferred length for that bit of string and it equates to a length that is a fraction of the vibrating string length that doesn't coincide with a string length or harmonic frequency that would be found on instrument when played in normal tunings. The exact fraction escapes me at present but I could look it up when I'm next in my workshop.

For the two setups you describe if the same amount of energy passes down that bit of string I would expect more to be absorbed by a bigsby than a stop tailpiece. Very loosely the more rigid and structure the more energy that will be reflected. But all things being equal the break angle wouldn't make a difference to this. The material properties of the bridge and tailpiece are what governs the rate at which the energy is lost. So if you were to simplify the comparison and say that you have two systems, one a stop tailpiece and the other the same tailpiece with those springs in it. The one with the springs would apply a damping or impedence to the energy in that part of the string.

You can measure these things and I've done so on archtops and violins, never on solid body or bigsby type tailpieces though but I'm certain that this would be the case. Increasing the break angle above the point at which a node is fixed will not alter the way energy behaves in the string behind the bridge. It will behave the same as energy does in the string in front of the bridge. In other words it will be lost via the body of the guitar through the bridge or via the tailpiece. The rate at which this happens depends on the physical and material properties of the bridge, tailpiece etc. The higher the coupling or downward force the greater the rate the energy is lost through the bridge.

In a nutshell though the break angle has little to do with these things on an electric. Yes it does happen physically but the few degrees change has little or no discoverable effect to the ear or when the harmonics of the note are mapped on paper. Adding a bigsby with the damping effect of springs will add to the decay behind the bridge and possibly suck more energy from the string causing more loss of both attack and sustain but intuitively I would suggest again that there is so much more going on it would not be as much as you might imagine. There is so much going on that it is rarely down to one thing.

To get a full idea of whats going on is very complex as energy is lost in many ways and at different rates for different frequencies and harmonic overtones. Its these that give colour to the sound and why the subject is so fascinating and utterly unfathomable..:)
 
In that case we have been on the same page from the beginning. Pity I lack your eloquence.
 
In that case we have been on the same page from the beginning. Pity I lack your eloquence.
Thats good. Just as long as you got this bit as wrong (I know you said your experience never agreed), tell those customers that that ain't how it is. :)
As I understand the physics of it, as you lower the tailpiece you increase it's mechanical coupling to the guitar body. By rights this should result in increased sustain.
 
All of you should buy Fenders. :)



Gods, but that would be a boring world. As it would if everyone bought Gibsons. Or Carvins. Or any other brand, for that matter.



Light

"Cowards can never be moral."
M.K. Gandhi
 
I haven't bought a guitar for nearly 25 years.:)

:) Neither would I if i could make my own.

I'd probably get carried away, though. You know, something double-necked, with around thirty sympathetic drone strings and a sculpture of a mermaid on the headstock.

yep, a little knowledge would be a dangerous thing for me.
 
:) Neither would I if i could make my own.

I'd probably get carried away, though. You know, something double-necked, with around thirty sympathetic drone strings and a sculpture of a mermaid on the headstock.

yep, a little knowledge would be a dangerous thing for me.
You gotta get those things out of your system. Then you'd actually build what people like and what you need...:)
 
This turned out to be an excellent, informative thread. Thanks to all. :)

So here's a question for you, Muttley. Since increased string break angle at the bridge increases the downward force on the bridge and causes string energy to be lost faster through the bridge, it follows (to me, anyway) that that energy is increasingly directed throught the bridge into the body - correct? And whatever attenuating properties the body/neck system possess would come increasingly into play and color the sound more than with shallower string angle? (Although this would be minor in any case with an electric.)

Just trying to get my head around all this. ;) :)
 
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