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Double Bass String angle across the bridge

R

riimodar

Aug 5, 2006
40
9
#1
Dear colleagues,

I'd like to ask you to do a simple measurement for me: What string angle across the bridge does your bass(es) have? If any of the luthiers here can comment on what is a normal/standard angle, this would be really appreciated.

Just for the case you are curious why am I asking this: Now I am dealing with a bass with a short bridge (14cm / 5.5inch). I believe this is a proper bridge for a given bass as the bass has a highly arched top and a thin saddle. The strings probably exert the same downward pressure to the top as when you have the standard 17cm/6.5inch bridge on a flatter bass with a standard saddle. I would like to justify this idea by comparing the string angle with other basses.

For a given string tension, the angle defines the downward pressure to the top. Unfortunately, it is not a common practice to measure the angle. The height of the bridge, the saddle, the (over)stand, they all are often discussed in relation to bass stiffness, tone character etc. These are all just partial data, while the definitive measurement is the angle. The saddle and the overstand heights influence the ease of access and esthetics, but the sound is in fact influenced by the angle.

Thanks for any measurements or comments.
 
#4
33° deg on my 5-string 4/4. About 7/8/9/10/11 mm action at the end of the fingerboard.
Thick top, could hold the tension of Spiro stark (but not my left hand ...).

I think it depends on the bass top and strings which angle is best for your instrument. For those with a weaker top, it would be possible to raise the saddle to make the string angle at the bridge smaller and reduce the pressure on the top when using medium to higher tension strings.
 
#6
DoubleMIDI said:
33° deg
Click to expand...
Thanks a lot for the first measurement!

1st Bass said:
I assumed that the angle in question was the angle the string makes, crossing the bridge (Nut to Bridge to Tailpiece) In a violin it is supposed to be 158 degrees
Click to expand...

Yes, this is the angle I meant. I thing this is also waht DoubleMIDI measured: there is 33 degree break (slope) after the string crossed the bridge. I.e. his 33 degrees is 147 degrees in your interpretation (180 - 33 = 147).
 
#7
To make clear what I mean by the string angle, I made photos of my gauge and how I use it to measure the angle.

On the concerned bass, the angles of individual strings differ a little, ranging from 30 degrees (G string) to 33 degrees (A string).
 

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#9
"Yes, this is the angle I meant. I thing this is also waht DoubleMIDI measured: there is 33 degree break (slope) after the string crossed the bridge. I.e. his 33 degrees is 147 degrees in your interpretation (180 - 33 = 147)."

OK, I understand. Thanks. I was wondering why the huge difference.
 
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#11
Hello
This discussion is very interesting. On cellos the angle is measured around 150/154 degrees usually.
My other bass has exactly 148 degrees measured on the D string. Does this seem usual ?
I'm now about to have my violinmaker install the new neck on my 18th century bass. I never heard this instrument as I bought it without setup. The arching is VERY high, not less than 8cm high belly! We have "carte blanche" to make the proper angle and bridge height... Who can help me ?
Have a nice day, greetings from Strasbourg, France.
 
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#13
The greater the angle the greater the pressure on the top. Usually that means a louder instrument.
Maybe possible because of the highly arched top, but it depends also on the shape of the arch and the thickness/stability of the top. I have seen a lot of sunken Pöllmann tops at a local luthier that needed to be replaced completely and we know that that's an expensive think.

But as far as the angle doesn't get too much unequal at the bridge you can later install an adjustable saddle to put off some pressure of the top if you think it might be too much, either structurally or soundwise. You cannot do that if you keep your neck angle or the action gets rather high.
 
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#14
My bridge is 15.5cm high and the angle you seek is 32/148 degrees. I have heard of a very high modelling associated with the name Stainer, especially in the smaller instruments (the violin, viola and cello). It could also be accompanied by very thin belly graduations that are possibly why the modelling needs to be so high. French basses tend to have flatter, thicker fronts.

I suggest that there might be another reason why a 6 1/2" bridge might be more efficient than a 5 1/2". My understanding is that the sound post limits movement of that-side foot of the bridge, turning it into more of a fulcrum. The other foot is positioned over the bass bar and is more free to rotate around this fulcrum. It acts like a piston that turns the largely horizontal string vibrations into vertical movements. For the same foot width a higher bridge will exert more leverage through this piston effect.

Perhaps the higher modelling will also affect the sound in other ways, such as the loudness of the G and E strings because of the shorter bridge legs and their reduced leverage.
 
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