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need help figuring out compensation

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need help figuring out compensation

Postby Matthew Lau » Tue Oct 24, 2017 10:07 pm

Dear Mimf,

I'm workign on an acoustic bass guitar, but have trouble figuring out the compensation.

Could you guys help?

I tried using the liutaiomottolla compensation calculator, but am probably doing things wrong.
Parameters keep shifting when I change tabs.

I'll be building a 4-string acoustic bass guitar, 34" scale, Thomastik Acousticore strings
E 41.2 Hz 26.5 lb/in .086 in dia 0.186" action at 12th fret 34 in scale
A 55 Hz 29.2 lb/in .086 in dia 0.165" action at 12th fret 34 in scale
B 73.416 Hz 27.3.5 lb/in .053 in dia 0.135" action at 12th fret 34 in scale
G 97.999 Hz 26.5 lb/in .041 in dia 0.12" action at 12th fret 34 in scale

nylon core

I'm pretty new to this, so am probably doing stuff wrong
Matthew Lau
 
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Re: need help figuring out compensation

Postby Peter Wilcox » Wed Oct 25, 2017 1:32 am

For starters, your string diameter is wrong for the A string. But what the calculator wants is the core diameter for the strings, which is unknown (to me.) The calculations seem to be heavily dependent on the core material and the core diameter.

If I use the default parameters for a 34" scale with nylon floss cores, I get the compensation of a straight saddle of 0.0518" for the G string to 0.097" for the E. I'd think for that small amount you could just shape the saddle without having to angle the slot.
Maybe I can't fix it, but I can fix it so no one can fix it
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Peter Wilcox
 
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Re: need help figuring out compensation

Postby Matthew Lau » Wed Oct 25, 2017 2:04 pm

Thanks!

I've built a few kits in the past and used plans, but this is my first "new" design (ripping off of Luittoto's Tinozza bass, but smaller body, different bridge, etc).
Matthew Lau
 
Posts: 346
Joined: Sat Feb 18, 2012 2:03 am

Re: need help figuring out compensation

Postby Matthew Lau » Wed Oct 25, 2017 2:04 pm

btw, Peter, I just realized that you're in California.

What part? Sometime, I'd like to get away from work and pay you a visit.
Matthew Lau
 
Posts: 346
Joined: Sat Feb 18, 2012 2:03 am

Re: need help figuring out compensation

Postby Peter Wilcox » Thu Oct 26, 2017 12:17 pm

Hi Matthew - I'm in Janesville, about 60 miles north of Reno on 395. Where are you located?
Maybe I can't fix it, but I can fix it so no one can fix it
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Re: need help figuring out compensation

Postby Jeff Highland » Thu Oct 26, 2017 3:12 pm

I built a bass a few years back using savarez nylon core strings. Compensation requirements were minimal, and pretty well straight across.
The nylon core has a much lower modulus of elasticity than steel so the tension does not rise as much when fretting.

I would suggest you try the strings on an electric bass with adjustable saddles and set it up for good intonation, then measure the result. Calculation alone will not get you there.
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Re: need help figuring out compensation

Postby Jeff Highland » Thu Oct 26, 2017 4:51 pm

I went back and measured what I have on my bass with the Savarez strings.
I would expect that what peter wilcox suggested would be very close
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