Bridge string notch effect on tone?

[polkat]

If the string notches on top of a violin bridge are too deep (or for that matter too shallow), how does this effect tone? Or does it?

Thanks!

[GMM22]

I think depth is non-critical to sound, provided the strings have zero clearance to rattle from side to side within the slot. There could be a secondary effect due to the potential difference in mass between a bridge having the same string heights but with deep slots or shallow slots, but it is likely a negligible factor, or at least one that could be swamped by other bridge cutting parameters. The aesthetic factor is important, and deep slots are a sign of inattention to detail. String slots can be much more shallow than one might think.

[Bill Yacey]

I think depth is non-critical to sound, provided the strings have zero clearance to rattle from side to side within the slot. There could be a secondary effect due to the potential difference in mass between a bridge having the same string heights but with deep slots or shallow slots, but it is likely a negligible factor, or at least one that could be swamped by other bridge cutting parameters. The aesthetic factor is important, and deep slots are a sign of inattention to detail. String slots can be much more shallow than one might think.

On my bridges , a dent is more descriptive of where the string sits. It doesn't take much to hold the string in place on the bridge. One quick swipe with a nut file is all it takes. I use these from StewMac:

[Oded Kishony]

In my experience deep grooves in the bridge are very detrimental to sound. I don't know the physics involved.

Oded

[~ Ben Conover]

Depth for string notches for bridge and nut = 1/3 of the string diameter.

[gowan]

If the string notches on top of a violin bridge are too deep (or for that matter too shallow), how does this effect tone? Or does it?

Thanks!

I know of a case where the C-string of a viola had somehow gotten deeply embedded into the bridge, to a depth about equal to the string diameter. It had a dulling effect on the sound of the string, almost like a mute applied just to that string.

[David Burgess]

I'm kinda with GMM on this. I haven't found that the depth of the grooves makes much of a difference, but anything you change to correct them will. If a groove is filled, it changes downforce and mass a bit. If the top of the bridge is trimmed, it changes total mass and mass distribution, and also the rocking frequency (for those who keep track of those things)

Groove is too deep; groove problem is corrected; sound changes; must have been the groove.

Oh, I too was taught that it hurts the sound, so I always get 'em right, sort of believing that it will help even though I have no evidence for it.

[Janito]

If the notch is deep, it would also change the incident angles of the string at the bridge.

[GMM22]

I could be wrong, but I think the OP was inquiring into notch depth independent of string angle. Or in other words, imagining the change in tone that might occur if one takes a given bridge with deep notches, and removes the excess wood from the top ridge until the notches are shallow, thus leaving the string angle unchanged.

One could reverse test this aspect without too much difficulty. Take a well trimmed bridge and glue five short sections of matchstick or wood fragments to the top, thus simulating the effect of additional mass. With strategic gluing, they could also be snapped off for quick A/B comparison. One might feel inclined to shortcut the experiment by adding an equivalent single lump mass to some point on the bridge, but of course this state would not simulate the even distribution of mass presented by a bridge with deep slots.

[polkat]

Yes, that was the intent of my original post. Over the years, this bridge, while very nice in all other respects, has had numerous types of strings on it, and the notches have worn down to where the strings (the G and D in particular) are sitting even with the bridge top. I have attached an image showing the D string on the bridge from the front (or back for that matter).

The G, D, and partially the A strings are held fairly snug for about 2/3's of thier diameters, and the strings are sounding rather dead, although they are nearly new (Helicores).

I'm wondering if the bridge notches are causing this, and if I lower the top until maybe 2/3's of each string is free if it will help?

Thanks!

notch.bmp

[Oded Kishony]

It's hard to dispute David's point that in order to fix the too deep notches the top of the bridge is usually shaved therefore changing the weight distribution. I suppose you could save the sawdust from the operation and weight it etc.

For a while I used to 'repair' cello bridges if they were otherwise ok by making the notch bigger with a round file then I would glue a small round dowel with krazy glue into the enlarged notch and finally replace the groove.

Oded

[David Burgess]

Don't mean to say I'm right and anybody else is wrong. I haven't come close to doing any good tests on this (didn't see the value because I just generally fix it anyway).

Things like this are a bugger to nail down. I'll go back to my concept of "sweet spots". A slight change in string angle over the bridge might either hit a sweet spot or deviate from one. A person observing the change in sound on one or several instruments might conclude that there is a trend, (higher string angle does this, lower string angle does that), when in fact the change can go either way depending on the fiddle.

The same thing can be true of small changes in bridge mass distribution.

Brings up an interesting question though:

What might we be leaving on the table (soundwise) by assuming that the bridge shouldn't extend above the strings?

Could it damp down an overly bright fiddle?

[Melvin Goldsmith]

Just being boring here but I reckon that a deep groove is more likely to combine with rosin dust and get a corrupting grip on the winding of a string lowering its useful life???? ...and maybe making it sound poor.

Also just totally speculating, but given that the player articulates the bow ribbon contact in colouring sound only a few mm from the bridge top we are discussing then maybe the contact of the string on the bridge top actually probably does have some effect...?

Also given that the bow might only be 10mm away I'd imagine that whether the sting is gripped to the height of 25% of diameter or 50% of diameter might actually make some difference to the dynamic.??????

[David Burgess]

Beats me, Melvin.

I think it was Pickering who said that the windings don't move on the bridge during playing, but that doesn't necessarily mean that the core couldn't move within the windings.

Sometimes the first step toward progress is debunking old beliefs.

Sometimes the old beliefs turn out to be tried and true.

[stradofear]

If the strings are sitting in deep grooves, most likely your violin will sound "fresher" because it's going to be getting fresh strings on a regular basis as the windings get ripped up and the strings unravel. Especially the A. This isn't the type of thing you need to ask much about, because you should be getting it fixed, ASAP, regardless of the tonal consequences.

If you want to do an experiment with the current situation, do not lower the tension on the string, but lift it a bit from the bottom of the groove, pull it back and forth a bit to equalize what might not have pulled through the notch, and set it back down. Does that sound better, or is there no change? As you speculate, you might have some string bunching up on one side. I notice this even with a normal groove--as you tune the string, the afterlength pitch doesn't always change, or, alternately, you can bias the afterlength pitch by tugging the on one side or the other of the bridge to see what effect it will have. Since this does make a change in the afterlength pitch, you can see that the string, even on a normal bridge, does not readily slide over the hump from one side to the other.

(edited for clarification)

[David Burgess]

Just read your bio, stradofear, still trying to figure out who you are.

You do some cool posts, so maybe at some point you'll emerge from anonymity? At least privately to me?

[MANFIO]

I'm also curious about the real identity of stradofear... Our world is so small...

[polkat]

Well, with Helicores being quite thin to begin with, it is a miniscule amount of wood to remove to bring the strings above the bridge top. I was planning to eventually cut another bridge for it anyway, so I'll try this first and let you folks know what effect (if any) it has.

[stradofear]

With Helicores, which like to saw through bridge tops, you might consider rubbing a skin of superglue over the top of the bridge to harden it, especially in the grooves. You can also, with the current bridge, fill the grooves with superglue, clean it all up, and refile a very slight notch in the superglue fill. This won't wear as quickly and may or may not give a sound you like.

[Ken Pollard]

Very small world.

1787 NW is pretty funny.

I like the bridge ideas here, too. When I first read the OP, I took it as a sawing action lowering the grooves. It hadn't occurred to me about the bunching effect, but then I always get after my students and customers to make certain to tip their bridge back into position, which helps equalize things as well, I'd guess -- though I sure hadn't thought of it that way. Good to have another way to look at it.

Ken

[Bill Yacey]

Very small world.

1787 NW is pretty funny.

I like the bridge ideas here, too. When I first read the OP, I took it as a sawing action lowering the grooves. It hadn't occurred to me about the bunching effect, but then I always get after my students and customers to make certain to tip their bridge back into position, which helps equalize things as well, I'd guess -- though I sure hadn't thought of it that way. Good to have another way to look at it.

Ken

The best way to do this is with a bridge jack / string lifter. This way when you lower the strings back down onto the bridge there is no bias pull one way or the other.

[Ken Pollard]

The best way to do this is with a bridge jack / string lifter. This way when you lower the strings back down onto the bridge there is no bias pull one way or the other.

Depends on what you mean by best -- using the bridge jack would help equalize the tension whether or not you moved the bridge. But most players don't cart bridge-jacks around with them.

If you support the bridge with thumb & fingers, fore & aft, then it will slide. This assumes the bridge is not wildly out of whack.

Ken

[Bill Yacey]

Depends on what you mean by best -- using the bridge jack would help equalize the tension whether or not you moved the bridge. But most players don't cart bridge-jacks around with them.

If you support the bridge with thumb & fingers, fore & aft, then it will slide. This assumes the bridge is not wildly out of whack.

Ken

What you say is true, but I wonder how long it takes for the string tension to equalize on each side of the bridge?

[stradofear]

Don't make it more complex than it is. Just put the index finger of one hand behind the bridge, the other index finger ahead, and lift the string. One at a time. Bridge jacks aren NOT for strings at tension. They put a lot of extra tension on the string, in the wrong place (you have to jack the strings much higher than necessary to free the bridge), and often/usually aren't the same curve as the bridge, so some strings can get stretched over their reasonable limit. Also, the string jack pulls strings on one side of the bridge, not both, bunching them on the jack side,which doesn't fix the problem we're seeking to fix.

[edi malinaric]

When the first steel strings appeared for the cello (early 60s iirc) my A-string quickly cut deeply into the wood of the bridge. At the time I was a poor student so I couldn't afford a new bridge. I took a leaf from those violin bridges that had a small ebony insert under the E-string and grabbed saw, chisel and file and carried out my own mod. under the A-string.

The improvement was very noticeable and later I treated the other strings as well.

Over time I have also thinned the top of the bridge - each time getting a slight improvement in tone. That is until I went to far and reached ~ 1.6mm. That was definitely too thin and a markedly backward step. So I glued a couple of plywood "risers" under the feet and reprofiled the top to lower the strings and thicken the top edge. Currently its at 1.8 to 2.0mm (A to C).

An attempt at reinforcing the back of the bridge with surfacing tissue and epoxy resin failed after about a year when the tissue peeled away. However the slight impregnation of epoxy resin into the wood fibres appear to have done the trick and the bridge has remained straight for the last ~6 years.

So what have I learnt?

i) Thinner, but not too thin, top edges sound better.

ii) Hard inserts under the strings prevent the strings from cutting into the wood.

iii) Epoxy alone can modify the wood sufficiently to prevent the dreaded "bridge bow".

That the cello sounds better is a bit of OK that doesn't displease me either.

cheers edi

cheers edi