Dual-n

A dual-n tuning is a tuning where two separate mappings are provided for a basis element, turning the one basis element into two basis elements.

The most common type of dual-n tuning is dual-fifth tuning, aka dual-3 tuning, where the subgroup 2.3 is replaced by 2.3+.3−.

However it is also possible to do this for any other basis element. You could have a dual-2 tuning, dual-5 tuning, dual-7 tuning, etc.

One situation in which it might make sense to use a dual-n tuning is for use with an equal-step tuning that’s good on all primes except one, but you don’t want to leave that prime out. You could use a dual-n tuning where n is that prime in order to make the equal-step tuning workable.

Many of the sooty fox scales themselves to dual-n interpretations.