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Double Bass String Tension Project

This project grew out of suggestions on the 2xbass list, a listserv for Double Bassists interested in furthering and contributing their knowledge of the craft. Questions about string tension brought forth a measurement method (see bottom of page) and suggestions that the data be gathered and posted for the benefit of all.

String tension goes beyond mere comfort and player preference to play an important part in the way the Double Bass produces sound. The best place to learn more about this is from joining the 2xbass list - click here to learn more about it.

I can take no personal credit for this information or project other than being the grateful recipient and host. If you have additional data, please email me at bob@gollihur.com with your contribution. Update 2011, geraldj@weather.net.

last updated August 31, 2011, by GNJ


Manufacturer

Model

Gauge

G

D

A

E

-

Comments

Corelli

370

Forte

67.5

61

63

59.5

-

from Dan Wilks

Supersensitive

Sensicore

orchestra tuning

53.5

52.5

52.5

56.55

-

from Dr. Gerald N. Johnson, P.E.

Thomastik

Spirocore

(thought to be)

46.3

48.9

61.8

66.9

from Dr. Gerald N. Johnson, P.E.

D'Addario

Helicore

published at the D'Addario web site

Jargar

dolce

?

54#

62#

?

?

-

from Dan Wilks

Kolstein

-

Gauge

40#

47.8#

58.4#

?

C=63.75#

42-1/2" scale (C on an extension), Dr. Gerald N. Johnson, P.E.

Pirastro

Obligatos

-

62#

66#

69#

68#

-

Comments

Picato

Innovations 140H (solid core)

-

57#

65#

71#

68#

-

Comments

Manufacturer

Model

Gauge

G

D

A

E

-

Comments

Individual Strings and mixed sets:

Mixed Set: (on a 5 string Pollman bass, 41-3/4 string length):

Kolstein B 67.9#
Spirocore E 61.3#
Kolstein A 63.9#
Kolstein D 67.8#
Spirocore G 47#
from Dr. Gerald N. Johnson, P.E.

D'Addario Orchestra Medium measured on Engelhardts vs. published specs. (The S-9 has a 42" string length, the M-1 41-5/8")

       S-9      M-1     D'Adarrio specification
G    64.3#    63.7#    62#
D    54.6#    63.7#    65.9#
A    58.2#    63.7#    69#
E    59.3#    63.7#    70#
from Dr. Gerald N. Johnson, P.E.

Picato Innovation braided-core D    58#
Jargar Dolce D                      62#

How can I measure string tension on my bass?

The 2xbass list Wizard of Water, Dr. Gerald N. Johnson, P.E., provides the following instructions to those without scientific measuring devices:

Diameter is only a good measure if the string internal construction is consistent from string to string and there are no voids, its all solid steel. Unfortunately that's not the case so I can't tell much by string diameter. But fortunately most of us do have the resources to measure string tension. This is a way to do it.

The tools needed are a length measure long enough for the mensur and reasonably will calibrated in the half inch or 12 mm range. An empty plastic milk, soda, or juice jug, 1 or two quart or liter is fine. Some paper clips or string, and a supply of clean water and a kitchen measuring cup. Water conveniently weighs very close to 1 gram per milliliter and makes a handy adjustable weight. I'll either neglect the weight of the jug or weigh an empty one here very carefully.

The same measurements can be made with a small spring scale to measure the pressure required for the same half inch deflection, just that water and jug is more commonly available.

Lay the bass on the side with the strings horizontal. It would be a good idea to have a helper make sure the bass doesn't roll over to the belly or off the table.

With a yardstick or steel tape measure the mensur, nut to bridge. That's an important variable and critical to the computation.

Hang an empty 1 quart or 1 liter plastic milk or juice jug on the center of the bass string by a chain of partially straightened paper clips or a loop of string.

With some reasonably precise measuring instrument measure the space between the string under test and a neighbor, dial caliper would be superb, a metal machinist's scale would be really good, a school ruler probably adequate, and a yardstick poor but not to be totally rejected. I can only use thumb width for deflection if the mensur is also in thumb widths...

Add water to the jug until the string spacing changes by 1/2 inch, as closely as possible. That's 12.7 mm. Or something in that range.

Then according to Marks Mechanical engineers handbook figuring deflection of a cable way under load, the universal formula neglecting the weight of the string is:

P = 4 * h * H / L

where h is the deflection, H is the tension, P is the deflecting load, and L is the length between supports. Deflection and length have to be the same units, tension and load also have to be the same units. E.g. mm and Kg or inches and pounds, or mm and pounds...

So for a mensur of 105 mm (41.228"), and a deflection of 0.500 inch, I get this table:

Tension weight ml water us fluid ounces of water
42# 2.032# 924 ml 31.2 fl oz
52# 2.516# 1144 ml 38.6 fl oz
66# 3.194# 1452 ml 49.0 fl oz
75# 3.628# 1650 ml 55.8 fl oz.

Rearranging the formula gives
h = P * L / (4 * H)
and using a 2 pound weight (909 grams)

Tension deflection
42# .492" = 12.5 mm
52# .397" = 10.09 mm
66# .313" = 7.95 mm
75# .276" = 7 mm.

using a 1 kg weight (2.2 pounds)

Tension deflection
42# 13.75 mm = .541"
52# 11.1 mm = .437"
66# 8.75 mm = .344"
75# 7.7 mm = .303"
42# tension is 19.05 Kg-force = 186.825 Newtons.
52# is 23.59 Kg-force = 231.3 Newtons
66# is 29.93 Kg-force = 293.6 Newtons
75# is 34.02 Kg-force = 333.6 Newtons.


Please send your string tension data and comments to bob@gollihur.com or to geraldj@weather.net






Copyright © 1999-2000 Bob Gollihur