I'm a little concerned about some of the assumptions being made about swapping strings.
I'm not pulling this out of a hat. Aside from building a few instruments of my own, I helped luthier Tony Karol (
www.karol-guitars.com) to tool up his shop for the switch from electric to acoustic guitars. I have seen his designs evolve as he went from being an unknown maker, to someone who builds for people like Stephen Bennett and Bruce Cockburn.
Solid body basses are essentially a plank with fine wires stretched across them. As long as the truss rod is good, there shouldn't be any issues when experimenting with different string types and gauges.
Acoustic guitars and basses are a different proposition.
- The body is built as light as possible. to optimize acoustic output.
- Acoustic basses are more of a challenge to build than guitars.
- Conventional flattops are particularly prone to issues, because the soundhole weakens the top along a plane in line with the string pull.
Here are some of the possible issues when you bump string tension up:
- The torque against the bridge pins and the saddle can cause the back half of the top to belly up, and the area between the bridge and soundhole to sag.
- As that s-curve builds up over time, it causes the neck to rise at the headstock. You may have seen this on acoustics where the action is too high and can't be lowered, because the saddle is already almost flush with the top of the bridge.
- The glue joint can fail, causing the bridge to separate from the top starting at the back edge.
- Bracing can separate from the the top.
- Tops can crack (especially solid tops).
There can also be major variations in tension on strings of the same gauge, depending on the type of core and winding materials used, the relative size of the core to the windings, etc.
You can check this out by clicking on the "Family Tension Chart" links on the D'Addario website.
Here are some long scale bass numbers to compare:
- ETB92 Medium long scale tape wound, 50-105, 146.1 lb.
- EXL170 Light long scale Nickel rounds, 45-100, 165.6 lb.
- EXPPBB170 Light long scale phosphor bronze acoustic, 45-100, 190.8 lb
- ECB81 Light long scale Chromes flats, 45-100, 199.75 lb.
And some guitar-scale examples:
- EJ16's, the standard 25.5" EXP light gauge 12-53 six-string steel core phosphor bronze guitar set. 156.3 lb
- EXPPBB190GS, the 37-90 nylon rope-core bronze-wound 4-string set used on a bunch of these basses. At the Taylor 23.5" scale, total tension is only 50.16 lb.
- A 37-90 set of Kalium nickel round singles, to illustrate the difference with a conventional metal-core string set: 59.2 lb
- A 31-86 4-string set of Kaliums, selected to roughly match the string pull on the Taylor: 49.5 lb.
Note that the tops on our guitar-scale acoustic basses are braced to sound good, have a strong output and be reasonably durable with about 140lb less string pull than something like a full-sized Dean or Ibanez ABG.
If overly heavy strings and/or poor humidity control damage the top, and neck reset is sometimes the recommended fix. This is a major, rather scary repair, and typically wouldn't be worth doing on a cheap acoustic bass. The Taylor has an advantage in that the bolt-on heel design allows for adjustments. Still, this is not a risk you want to run, especially since a bowed top typically has a negative effect on sound production.
This is why some of the manufacturers are playing hard to get when we ask about switching string types.
I would be reluctant to increase string tension more than 10 to 15%, compared to the stock strings on our respective basses. That only gives you about 5 to 8 lb leeway in overall tension.
That still presents some options for assembling custom sets from singles. Provided that the tuning pegs will accept them, this could be done without risking mayhem.
More on that tomorrow...