What's the effect of bridge thickness to the sound of the bass?

Aerdna · #1 06-03-2008, 01:59 PM

On the same bass, how would a bridge that is overall too thin sound in comparison to one that's too thick?

forester · #2 06-04-2008, 10:38 PM

forget the word "too" it denotes trouble from the start. the whole idea is balance. thin..crisper,responsive,scratchy,shortlived and prone to failure.
thick..dull,clumsy,less responsive. none of this is gospel..just limited observations

Jake deVilliers · #3 06-05-2008, 01:12 AM

It may not be Gospel but it echoes my experience.

To me thin bridges sound quick and lively, thick ones sound slow and stodgy. Its more about the response than the sound, though I think the tone suffers a little with thick bridges.

MIKMAN · #4 06-06-2008, 10:56 AM

Jake, when you say thick you mean more than 20 mm in the feet and more than 4.5 mm in the strings?
Michael

Jake deVilliers · #5 06-06-2008, 09:37 PM

I usually aim for 20-21mm at the feet and 4 1/2 to 5mm at the top on a 3/4 bass.

Thick is probably 23mm or more at the bottom and 7mm at the top. I just measured one in my bridge box with 25mm feet - they obviously didn't thin it at all!

Martin Sheridan · #6 06-07-2008, 01:41 PM

I have probably made a thousand bridges or more for basses.
My proceedure is to fit the feet first and then work on the curve and height of the strings. At this point the bridge is much to thick and the curve of the feet is still way too much.
The sound difference from this point to good dimensions as stated by Jake is phenonmenol. As you take the upper part of the bridge down the sound of the bass starts to come alive, but doing this much and leaving the feet thick leaves a lot to be desired. It's too bad that players usually can't be present as the bridge is being made to see and hear the difference. Sometimes someone comes in who has a bridge that's too thick and when they come back after it's been corrected they are always pleased and surprised at how much the tone of the bass has been improved.

I think I've mentioned this before, but years ago a luthier told me about "fast" and "slow" bridges. You can take a bridge and toss it onto a wooden workbench or the floor and some of them will just make a thud while others will "dance" and have a livelier sound. He had a theory about when to use each kind of bridge, but I've always thought that the ones that dance are the ones I want to use on the good basses, and save the others for kindling.

forester · #7 06-09-2008, 06:19 PM

you can tell the good ones by the way they "tick" on the sander

robobass · #8 06-11-2008, 02:23 PM

Good Topic! I bet very few basses out there could not be noticeably improved by spending an hour seriously fiddling with the bridge thickness. Of course you have to be willing to risk thinning too much, and starting anew. One thing I learned the other day. I was getting some adjustments on my Pfretzchner, and my Luthier said my bridge was too thick at the top. I said I felt my bridge was on the thin side already. He clarified that he didn't want to thin the bridge overall, but only at the very top. The idea being that shorter string grooves free the string and allow wider and clearer envelope. I let him do it, and it seemed to work. I've never heard about this before.

Next we should get into the can of worms that is bridge width. There is already a brutal religious war being fought over the proper spacing of bridge feet, but what about the afterwidth of the bridge top? I think this cause is also worthy of no small amount of bloodshed. My personal belief is in a bridge with closely spaced feet, little afterwidth at the top, but not too thin. I don't know why I like closer feet, I just do. It seems to respond faster and stronger. With a narrower top that still has thickness, you reduce mass, but keep the stiffness. Again, I think it speeds response and gives a certain firmness.
Who's willing to strap on a vest?
Robobass

martinc · #9 06-11-2008, 03:15 PM

I have been reading about the bridge thickness measurements in this thread. So a couple of days ago ( being a tinkerer), I measured mine which is a good quality Panpi. I fitted and shaped it myself a couple of years ago but used the specs from a previous bridge.
The top (string notches) was 7mm. Hmm. Too thick according to Jake. The feet were 21 which is OK.
So....last night I got out the sandpaper and files and went to work on the upper half of the bridge to take more wood off and get the string notch thickness down to 4.5mm.
After that was done I put a little boiled linseed oil on the bridge and put it back on the bass. I left it overnight to settle in.
When I played it this morning I noticed some difference. A bit more body to the overall sound. A tad less "mud" too. Its a ply so we are talking "thump" as a general quality.....now I have a more clear thump

But the biggest surprise is that I also have no string vibration at all. I assume its because of the shorter string slot.
I did not take a lot of wood off the bridge but I can definately say the sound changed. In this case for the better.
I could probably improve things more by taking a bit more wood off the central part of the bridge above the heart but I kinda like the change in sound so I will leave it alone except for some shaving off the outside and heart edges.
As Martin Sheridan noted...its doesn't take much to hear a difference.
So thanks everyone.

Jake deVilliers · #10 06-11-2008, 07:25 PM

That's a good experiment Martin. Its easy to learn something real when you make only one change at a time.

What do you mean by "But the biggest surprise is that I also have no string vibration at all."? That sentence has me completely confused!

Jake deVilliers · #11 06-11-2008, 07:32 PM

Robobass, you should know by now that I consider weight to be the enemy of sound on a plucked instrument, so I like your bridge description. At least the top part....

I still the think that the bass bar has a say in the span of the feet. Are you proposing to ignore that dimension or just to cheat on the narrow side with the toes over the bass bar rather than the leg?

Eric Rene Roy · #12 06-12-2008, 03:45 AM

Quote:

Originally Posted by robobass

My personal belief is in a bridge with closely spaced feet, little afterwidth at the top, but not too thin.

Ever look at the difference between a French & Belgian cello bridge? I love Belgian bridges on wide cellos like Montagnana's and such...maybe we need to make a Belgian bass bridge and give it a whirl!

martinc · #13 06-12-2008, 08:57 AM

Quote:

Originally Posted by Jake deVilliers

That's a good experiment Martin. Its easy to learn something real when you make only one change at a time.

What do you mean by "But the biggest surprise is that I also have no string vibration at all."? That sentence has me completely confused!

Jake:

I have been hearing a very slight vibration...or overtone...or something. Not enough to make me go crazy though. At first I thought it was a nut or bridge groove problem and recut both. Still there on all strings. Then I thought it might be the change I made from a wood tailpiece to the Wittner tailpiece/Pecanic cord combo last year. Not that. I put it down to a component of string "growl".
I checked again this morning and the sound of every string is still as clean as it was immediately after I sanded down the bridge and string notch length. Pure string tone only. Didn't realize what I have been missing these past two years.
I am now convinced it was a very minor vibration caused by the 7mm long string grooves on the bridge.

Jake deVilliers · #14 06-12-2008, 09:58 AM

Okay, I get that. You think you had a little 'sitaring' in the bridge slots - that tiny tingle that I mostly hear on guitars and mandolins that's caused by too long or too straight string slots.

I'm glad your bass is speaking well now - so often its the little things that are holding an instrument back.

robobass · #15 06-12-2008, 03:14 PM

Quote:

Originally Posted by Jake deVilliers

I still the think that the bass bar has a say in the span of the feet. Are you proposing to ignore that dimension or just to cheat on the narrow side with the toes over the bass bar rather than the leg?

Yes of course. The spacing is limited by the placement and width of the bar, but even with that in mind there is plenty of room for "cheating". I'm not a luthier. What are the accepted rules as to how much of the foot must stand over the bar?
Robobass

martinc · #16 06-13-2008, 08:43 AM

Jake wrote: "I'm glad your bass is speaking well now - so often its the little things that are holding an instrument back."

Jake: My goal is to get the maximum output that my bass is capable of producing. I include the sound from my hands in that equation too.
As J.S. Bach would say when he played a new pipe organ he liked: "It has good lungs!"
My German ply doesn't come under the same quality category as a new pipe organ but the changes I have made have definately made it respond better to my ears. Dunno if 'ol J.S. would have agreed though.