Workshop: Bad intonation? Gee, I wonder why?

This is a '30s Regal tiple that came in for consignment. Its owner had much work done to it -- a neck reset, new bridge, setup, etc...

However, the moment I took a look at that bridge I said, "that doesn't look right." Yeah, it wasn't. It turns out the last guy to work on this chopped-down and modified a classical guitar bridge to fit in the same spot as the original.

In the above photo I'm measuring from the back of the nut to the 12th fret -- 8 3/8" -- multiply that by two (16 3/4") and you get the scale length where the highest/trebliest string should "break" at the saddle.

However... the string "breaks" 1/8" behind that per this bridge's saddle slot, so that's not going to work.

Let's not forget to mention that tiple strings do not intonate at the same angle as a steel-string or classical guitar, so... the whole thing is silly right now.

The "front deck" of the bridge and the saddle itself are also too high -- at tension this would have 3/32" action height at the 12th fret which is fine for the low E of a guitar string... but feels terrible with 10 treble-ish strings on a tiple. Mandolins, tiples, mandolas, and similar-size steel string instruments can run at about 1/16" or a hair under, generally, at the 12th fret.

So -- my attack plan was: shave the front deck of the bridge down, cut a new slot, and put a new, drop-in compensated bone saddle in place.

As you can see, I've notched the top of it to accept the strings (and keep them in a good path) and have compensated all of the saddle slots individually for each string. This helps keep all of the 12-string-style octave strings happier as you go up the neck.


Warren said…
Excellent problem solving Jake!!!