Multiscale / Fanned Frets
Optimizing string tension and playability by varying scale length
Normal fan: Longer bass scale increases tension on low strings. Try setting treble > bass for a reverse fan.
Scale Length and Tension
The fundamental frequency of a string depends on three factors: length, tension, and linear mass density. The relationship is:
Rearranging to solve for tension:
Notice that tension scales with the square of the scale length. If we increase the string length, more tension is required to reach the same pitch.
The Problem with Standard Guitars
On a standard guitar, all strings share the same scale length (typically 25.5" for Fender or 24.75" for Gibson). This creates a tension imbalance:
Low Strings
- Floppy feel, especially on extended range guitars
- Less sustain and definition
- Intonation problems due to string stretching
- Requires thicker gauge strings as compensation, which can be harder to play
High Strings
- Higher tension means harder bends and vibrato
- Wider fret spacing makes stretching harder
- Can use thinner gauge strings, but they may feel too tight and have a brittle tone
A Solution: Vary the Scale Length Across the Strings
Multiscale guitars use different scale lengths for each string, increasing gradually from treble to bass. A typical configuration might be:
This gives us the best of both worlds:
More tension on low strings
Keeps them stiff. Improved sustain and more consistent intonation.
Comfortable tension on high strings
Easier string bending and vibrato for lead playing. Closer fret spacing for faster runs and smaller stretches.
Ergonomics and Playability
The fanned frets actually match the natural angle of your fretting hand better, especially in lower positions!
Why the Frets "Fan" Out
If the bass strings are longer than the treble strings, the nut and bridge can't both be perpendicular to the strings. The frets must be angled to maintain proper intonation on each string. This is still achieving the correct fret positions for 12-tone equal temperament, just at an angle rather than straight across.
The math for 12-tone equal temperatment still works: Each fret is still placed at the correct ratio (2^(n/12)) along each individual string, achieving 12 equal-tempered semitones per octave. The frets just connect these points at an angle rather than straight across.
There's typically a "neutral point" where the fret is perpendicular, often around the 7th-9th fret. Above this point, the frets angle one way; below, they angle the other way.
Extended Range Guitars
Multiscale design becomes increasingly important as you add lower strings. On 7, 8, or 9-string guitars tuned to drop tunings:
A standard 25.5" scale makes a low F# (on an 8-string) feel too loose to play well, while a longer 27" or longer scale makes the high strings too tight and hard to bend.
This is why multiscale designs have become so common in the extended range guitar market. They allow players to have a playable tension on all strings without resorting to extreme string gauges or sacrificing tone and sustain on the low end.
Summary
- String tension increases with the square of scale length (T ∝ L²)
- Longer bass strings = more tension = stiffer, more articulate low end
- Shorter treble strings = easier bends, closer fret spacing for leads
- Frets must fan out to maintain proper intonation at different scale lengths
- The angled frets actually improve ergonomics for many players
- Multiscale is strongly preferred for extended range guitars to balance tension and increase playability