String Tension ~ Luthiery Laboratories

String Tension

I crunched some numbers based on the excellent data that D'Addario provides, and it turns out that a 25.5" scale bass is quite workable with off-the-shelf string sets. The trick is to get a 5-string BEADG long-scale set and discard the G. Tune the remaining strings to EADG. This is equivalent to capo-ing the long scale at the 5th fret, or lopping 5 frets off the neck, so of course, it will work! In hindsight, it's all pretty obvious. I worked out the following scales and string sets:

25.5" scale:
EXL-160 (.135) : 185.4 * pounds total tension
EXL-170 (.130) : 154.6

27.0" scale:
EXL-160 (.135) : 207.8 pounds total tension
EXL-170 (.130) : 184.6 *
EPS-220 (.125) : 164.8

28.5" scale:
EXL-170 (.130) : 205.7
EPS-220 (.125) : 183.6 *

* indicates my best choice

For comparison, D'Addario EXL-160 105-50 EADG has the following total tensions:
34" scale : 202.2 pounds
32" scale : 179.1 pounds
30" scale : 160.5 pounds

For the 34" scale, the EXL-160 105-50 individual tensions break out as:

E : 40.3 - 19.9%
A : 48.4 - 23.9%
D : 60.1 - 29.7%
G : 53.4 - 26.4%

and the ratios stay exactly the same as the scale length varies. These strings play very nicely down to the 30" scale, but would probably get very sloppy below that. For the 5-string sets above, the ratios stay in the ballpark, except that the highest tension shifts from the D to the G, which makes sense, as the new G is formerly the D. If building a custom string set, you might want to replace that string with a lighter one, but I don't think that is absolutely necessary.

Another not-insurmountable problem is the tuners. A .135" string is a honking big piece of metal that is not going to want to wrap around a string post. You could force it, or you could strip the wrapping off the end and then re-secure it somehow (solder).

If you don't like these strings, any equivalent set from your favorite manufacturer should give similar results.

Building Necks

My take on necks

When you play a guitar, are you tightly clutching the neck, or are you holding mostly air? Even if you tightly clutch the neck, does the actual shape really matter? As long as it does not present any obstacles to movement, the answer is NO. So what is all this fussing over neck profiles? MARKETING, that's what. The actual curve around the back of the neck is fairly irrelevant, apart from the overall thickness.

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RetroBrite

"RetroBrite" is a name for a process that restores old yellowed plastics to new. Many plastics yellow or darken over time. RetroBriting can reverse this aging, but with a number of caveats that, in my opinion, make it pretty useless. While the process actually does work - it reverses the discoloration - the effect is temporary. After a few months, the plastic will return to its yellowed state. When this happens, you can repeat the treatment, but at some point the chemicals involved are going to start to degrade the plastic.

My first experiment was whitening some yellowed tuner knobs, and it did work. With nothing more than sunshine and hydrogen peroxide, the knobs lightened considerably. That was several years ago, and today the knobs are as yellow as ever.

What causes this yellowing? It is variously attributed to sunlight, oxygen, bromine content, and other causes. While all of these things can contribute to it, none of them are necessary. Some plastics simply turn yellow with age, and nothing will stop it. In my experience, the real culprit is simply bad plastic, and the only real solution is replacement.

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