What difference does shaving down a bridge (not saddle) make on tone??

[soma89]

So I have a Yamaha FG 200 from the mid 70s.

Sounds great and plays great BUT only because i sanded down the bridge AND saddle to get it to where I need it to be in order for it to be playable and have a semi-decent break angle.

I find the guitar to be very lively and light weight.

But am I loosing tone with a shaved down bridge? The intonation is shockingly pretty good.

[sdelsolray]

The amplitude, timbre and sustain is somewhat dependent on the height of the strings above the guitar's top near the bridge. If you shorten that distance (by shaving down the bridge and saddle), amplitude, timbre and sustain are affected to some degree.

[ChalkLitIScream]

If you shave the bridge, you remove mass from the system. This will inevitably change some characteristics of the sound made.

From what I speculate, removing mass is 'desirable'- this is based off similar processes to remove unnecessary mass from the top when making it, scalloping braces, etc. Less mass should allow the guitar to vibrate better.OF course, stability and strength may somewhat be compromised, but I imagine it will be negligible since you arent removing the entire bridge or anything.

Im not entirely sure what less mass means in terms of tone. I would hypothesize that it would have an increased bass response (scalloped braces tend to lead to this). On the other hand, I can back this up using people's responses to different saddle material. Folks with denser material (bone, metals) do report increased treble presence, so this leads me to believe less mass= bass, more mass= treble

[charles Tauber]

Originally Posted by ChalkLitIScream

this leads me to believe less mass= bass, more mass= treble

In general, the exact opposite.

What you have not recognized is the reduction in stiffness by reducing the height of the bridge. The reduction in mass is proportional to the height of the bridge: the reduction in stiffness is proportional to the cube of the height and diminishes much faster than the reduction in mass. Reduction is mass favours treble response: reduction is stiffness favours bass response. So you have two competing responses.

The answer to the OP's question is to use his own ears. He knew what it sound like before he reduced the bridge height and he knows what it sounds like now. He might not hear a difference, in which case, that's the answer. Not all changes are audible.

[RustyAxe]

You should be the one telling US ... what did it sound like before, and what does it sound like now? Shaving down the bridge is a stop-gap measure when the real problem is that the neck needs to be reset.

[dcmey]

Originally Posted by RustyAxe

You should be the one telling US ... what did it sound like before, and what does it sound like now? Shaving down the bridge is a stop-gap measure when the real problem is that the neck needs to be reset.

Exactl what I was thinking.

[Rodger Knox]

There's at least three changes. The weight and stiffness of the bridge, and the height of the strings above the top. Reducing the weight of the bridge may increase responsiveness, or reduce headroom, or both. Reducing the stiffness will probably have little effect, the bridge provides transverse stiffness and even a shaved bridge will have more than enough. Reducing the height of the strings will reduce the rocking force on the bridge, which will reduce the energy in the long dipole resonance. The long dipole contributes very little in power, but can have significant impact on tone.

As I've learned from Al Carruth, where that ends up depends on where you started.

[Alan Carruth]

Thanks Roger: that would have taken me at least a page....

[Tico]

What about the break angle? (BA)
I think the greater the BA, the greater the force the strings put on the saddle/bridge.

At least that's what I read here about slot-head guitars.
This, and the claim that the greater BA puts more downward force on the nut, resulting in the strings transfering more energy/sound/tone to the guitar.

If the saddle and bridge were lowered by different amounts the BA would change.
If saddle and bridge were lowered by the same amount the BA would not change.

[Alan Carruth]

I did a rather thorough experiment on the effects of break angle and string height off the top some time ago. People often change the break angle by putting in a taller saddle, and report that the guitar sounds better. I worked out a way to isolate the two variables of break angle and height off the top, and made careful measurements of the sound output of the guitar under identical plucks, and also listening tests to see whether people could hear the difference. The results were pretty clear.

In the listening tests, when I had people compare the sound when the break angle was different but the string height off the top was the same they were guessing, saying it was 'the same' about half the time and 'different' the other half. This was true across the board; no individual got it right significantly more often. When they listened to the sound when the string height was different, but the break angle was the same, almost everybody heard the change.

Measurements showed that there was no significant difference in the sound the guitar produced when the break angle was altered. When the strings were raised further off the top there was a bit more energy in the signal at two frequencies.

One was the second partial of the string. This is due to the fact that the string gets tighter twice for every full cycle of vibration, and pulls the top of the bridge toward the nut. This 'rocking' motion of the bridge doesn't produce much sound, for a number of reasons, and didn't add to the power of the instrument as far as I could tell with the measurements I could make. However, it does change the timbre somewhat.

The other frequency that had a little more power was the 'zip tone', the high pitched sound you hear when you run your hand along a wound string. Plain strings can do this too, but you usually need to use something like violin rosin on your finger to get it going. The point is that there is some of this sound in the string when you pluck it. It's a lengthwise compression wave in the string, sort of like what you'd get in a long air column, and it tends to rock the bridge as well. Because it's at a high frequency (typically between the 7th and8th partials of the string), and often dissonant, it doesn't take much sound from this to make an audible difference. Again, it didn't make the sound more powerful overall than that of the 'low' string, it just changed the timbre in an audible way.

Making the break angle higher does have one effect for sure: it increases the tipping force on the saddle. This tends to deform the slot and, in extreme cases, can break out the front of the bridge. Structurally there's every reason to keep the break angle as low as you can. Acoustically, so long as the string stays in contact with the saddle top through it's whole vibration cycle, and doesn't roll from side to side, it will transmit all of the of the signal to the saddle. What the saddle and bridge do with it after that is their business....
This probably doesn't require more than about a 15 degree break angle, which is what you get on most guitars over the nut.

[Wade Hampton]

Soma, any guitar that goes from being almost unusable to being easy to play is going to sound better, regardless of aspects like mass versus stiffness, for the simple reason ANY guitar that's getting played sounds better than one that's leaning against the wall of a closet and isn't getting played.

There are a lot of theories that can delve into what supposedly optimal setup characteristics affect what aspect of the tone, but what happens in these online discussions about this is that many of the folks who join in these thread act as though all of these different factors are measurable and mostly unchanging.

But I change the tone of my instruments with my attack, my palm-muting, where I place the pick, how hard I squeeze the pick, where I grasp the pick - along the edge or further back? - and all of these instantly changeable energy inputs have easily as much impact on the tone as a few tiny fractions of an inch off the thickness of the bridge.

More importantly, I can change them on the fly, mid-song, mid-phrase, and I don't have to use sandpaper to do it. I can even grab another pick made from a different material and maybe a different thickness, and instantly change all the other parameters that I've been experimenting with using the previous pick.

So please don't read too much significance into the modification you made of the bridge. Yes, you removed some mass, and yes, that likely made some small impact on the tone of the guitar. But you can have far more tonal impact just with your hands and how you work a pick, as I tried to explain above.

The tonal impact of your bridge modification, which was necessary to return the guitar to playability, is truly unimportant when compared to the benefits you gained from doing the work. It was a good call on your part, no matter what some other person sitting at another computer in a city far away might tell you.

You got the guitar playable again and now it can be used for its intended function. There is no downside to this whatsoever. Simple as that.

Hope that makes sense.


Wade Hampton Miller

[soma89]

Originally Posted by Wade Hampton

Soma, any guitar that goes from being almost unusable to being easy to play is going to sound better, regardless of aspects like mass versus stiffness, for the simple reason ANY guitar that's getting played sounds better than one that's leaning against the wall of a closet and isn't getting played.

There are a lot of theories that can delve into what supposedly optimal setup characteristics affect what aspect of the tone, but what happens in these online discussions about this is that many of the folks who join in these thread act as though all of these different factors are measurable and mostly unchanging.

But I change the tone of my instruments with my attack, my palm-muting, where I place the pick, how hard I squeeze the pick, where I grasp the pick - along the edge or further back? - and all of these instantly changeable energy inputs have easily as much impact on the tone as a few tiny fractions of an inch off the thickness of the bridge.

More importantly, I can change them on the fly, mid-song, mid-phrase, and I don't have to use sandpaper to do it. I can even grab another pick made from a different material and maybe a different thickness, and instantly change all the other parameters that I've been experimenting with using the previous pick.

So please don't read too much significance into the modification you made of the bridge. Yes, you removed some mass, and yes, that likely made some small impact on the tone of the guitar. But you can have far more tonal impact just with your hands and how you work a pick, as I tried to explain above.

The tonal impact of your bridge modification, which was necessary to return the guitar to playability, is truly unimportant when compared to the benefits you gained from doing the work. It was a good call on your part, no matter what some other person sitting at another computer in a city far away might tell you.

You got the guitar playable again and now it can be used for its intended function. There is no downside to this whatsoever. Simple as that.

Hope that makes sense.


Wade Hampton Miller

Thanks!

I was interested in hearing the theories of what happens to a guitar when the bridge is shaved. I didnt have a chance to A/B it as the guitar was unplayable before.

Anyways, I am happy with the results as well. I wouldnt wanna pay for a reset as it was a $80 purchase...but price and neck issues aside, this old YAMAHA fg200 puts a smile on my face when I pick it up.

[fazool]

Originally Posted by soma89

...I wouldnt wanna pay for a reset as it was a $80 purchase.......

You may not have been able to anyway.

In the 70's Yamaha had the horrible idea to epoxy their necks in place - suggesting this would make them more stable over a long time.

What they found was that the necks still need a reset but are now essentially not removable. So people have gone to extremes like sawing the neck off and bolting it back on, etc.

So, If you had one of these unfortunate things, shaving the bridge was your best bet, IMO.

[Truckjohn]

Generally... Here's my experience with shaving bridges.

Weight acts like a low pass filter... A heavier bridge tends to make a guitar sound more bassy by killing the trebles...

Removing bridge bolts and/or shaving the middle of the bridge tends to remove more weight than stiffness.... It tends to make the guitar both more trebley and more responsive. As a side effect - you get more string noise, pingy noises, and sometimes wolfish notes.... ....

Shaving the wings of the bridge tends to make it more flexible.... And this tends to make a guitar more mid rangey and more bassy depending on how you do it...

The downside is that the top tends to flex and belly more..

[gregsguitars]

The only time(s) I have ever shaved a bridge was only in front of the bridge saddle ,I have never shaved a bridge to get any action relief, My personal opinion for a proper set up on an acoustic guitar that has high action is aneckset,new bridge saddle and new nut...