Negative Frets / Fretboard Extension. How to do it?

[PTU 7's.]

Hello!

I'm starting to experiment with negative frets ala Kubicki Factor X, Rick Toone, Strandberg, etc etc etc

I have some questions:

- How do I measure those 2 extra frets? I think that I can use the 10th fret of the scale I'm using as the new 12th fret, right. But don't know how to calculate those new extra negative frets.

- Is this possible to do this with multiscale? Because Strandberg did it with a straight nut, but instead, Rick Toone, made it multiscale.

Here are the examples:

http://www.ricktoone.com/2012/02/blur-8-string-extended-range-guitar.html

https://strandbergguitars.com/portfolio_page/16-demo/

https://strandbergguitars.com/portfolio_page/8-tosin-abasi-guitar/

- Also want to try a capoable solution. That would be a bonus.

 

Thanks for reading!

 

Frank.

[curtisa]

Fret spacing is determined by the twelfth root of two (roughly 1.059), That is, each fret will be closer to the next as you go up the fretboard by a factor of 1.059.

For example, if you had a scale length of 25" and you knew the distance from the nut to the first fret was 1.403" (lots of fretboard calculators out there in Googleland), the distance from fret 1 to fret 2 would be 1.403/1.059 = 1.3248". The distance from fret 2 to fret 3 would be 1.3248/1.059 = 1.251", and so on...

To go backwards from the nut to a negative value would mean taking the distance of the nut to the first fret and multiplying by 1.059. So nut to fret -1 would be 1.403 x 1.059 = 1.4858". Fret -1 to Fret -2 would be 1.4858 x 1.059 = 1.573".

[PTU 7's.]

Thanks for your answer, Curtisa. I'll give it a try later and see what happens.