I have a thing about tension. It comes form being a Physicist who studied the Physics of musical instruments in college (nerd alert). Once you know certain stuff (the more you know...), it's difficult so unlearn, (or shut up about it).
Most string sets are designed by folks who don't really understand the Physics of string tension. Each string on your bass vibrates at a frequency of 4/3rds the frequency of the one below it. For even tension, the string diameters should also follow that progression (but going the opposite way) - take the diameter of you highest string, multiply it by 4/3, and there's what the next string diameter should be. The steps should not be even in terms of the difference between numbers (that's an arithmetic progression), the steps should be even ratios (a geometric progression). 45-65-85-105 is NOT a good set in terms of keeping the tension the same, and a 125 is very out of line with that set - why is your B string floppy? Because it's too small.
I like low tension strings. I've had wrist issues, so part of staying healthy is low tension strings, plus I like the twang they give you. I have two different gauge sets that I typically use. My "heavy" strings are 40-55-70-95-130, Notice that the strings don't follow the 20 thousandths difference - that's what a geometric progression looks like. And yes, a 95 E and a 130 B have the same tension - about 35 pounds each. If you like a 105 E (nothing wrong with that), your B should be a 140 to keep the tensions similar. The tough thing about this is, if you decide to go my route, you can't buy 5 string sets off the rack - you may find a 4 string set and a single B that work together.
The other gauge set that I use (from Kalium) is 37-51-70-94-130. Similar tension in 3 of the strings, but the highest 2 strings are a bit lighter, and twangier. I use Kaliums on my basses that like bright strings.
I also gravitate toward balanced tension myself. (As an aside, I'm less concerned with string-to-string timbre consistency.)
I'd like to pick your brain a little, if I may.
Traditional, D-string heavy gauges have been suggested to have originated from the need for the D to sound as loud as the neighbouring A through a flat, single-coil P-bass pickup, with a narrow-radius fretboard. This because, however little the difference in string height, it matters in terms of magnetic field strength. Or something like that.
[It may just be that, whereas double bass high strings have some amount of silk damping (which makes them sound bassy, but also complicates the manufacturing process, which in turn adds time and cost), bass guitar high strings sound twangy on a 34" scale instrument, unless significantly bumped up in gauge.]
The thing is, I have no background in physics (to speak of, at least) and a lot of trouble weighing the relative magnitudes of different parameters that appear to play a part in determining the relative output of a string:
- a fatter string has more magnetically-active mass than a thinner one
(I suppose core and winding have different degrees thereof, though, which may add a non-trivial element of complication)
- however, plucking force being equal, doesn't a looser string move more than a tighter one?
(if so, an additional question: how much is tension proper the more important element? or is the higher flexibility that the thinner string presumably exhibits the more important element?)
- then again, a more massive string should have more momentum than a lighter one. Or something.
So...yeah. Common sense is of limited usefulness in understanding facts of nature, and my own gives me contrasting signals to go by, with the result that I can't quite picture what's going on. Especially the relative weights of the above elements.
Thank you in advance for any insight you may offer.
