420edo: Difference between revisions

Eliora (talk | contribs)
Music: explain why this is included
Theory: enfactoring is a fundamental RTT concept so that subsectioning doesn't make sense to me
Line 3: Line 3:


== Theory ==
== Theory ==
420 is a largely composite number, being divisible by all numbers inclusively from 2 to 7. It's other divisors are {{EDOs| 10, 12, 14, 15, 20, 21, 28, 30, 35, 42, 60, 70, 84, 105, 140, and 210 }}.  
420edo is [[enfactoring|enfactored]] in the 7-limit, with the same tuning of [[3/1|3]], [[5/1|5]], and [[7/1|7]] as [[140edo]]. The [[13/1|13th]] [[harmonic]] is also present in 140edo, and ultimately derives from [[10edo]]. The [[29/1|29th harmonic]], while having significantly drifted in terms of [[relative interval error]], has retained its step position from [[7edo]]. In addition, in the 29-limit, only 11 and 17 have step correspondences coprime with 420. This means that all other approximations are preserved from smaller edos, thus enabling edo mergers and mashups.


Remarkably, approximation to the third harmonic, which it derives from 70edo, constitutes 666 steps of 420edo. Nice.  
420edo is better at the 2.5.7.11.13.19.23 [[subgroup]], and works satisfactorily with the 29-limit as a whole, though in[[consistent]]. In the 11-limit, it notably tempers out [[4000/3993]], and in the 13-limit, [[10648/10647]].  


=== Largely composite number theory ===
=== Odd harmonics ===
Being a largely composite number of steps, 420edo is rich in modulation circles. 420edo is [[enfactoring|enfactored]] in the 7-limit, with the same tuning of 3, 5, and 7 as [[140edo]]. The 13th harmonic is also present in 140edo, and ultimately derives from [[10edo]]. The 29th harmonic, while having significantly drifted, has retained its step position from [[7edo]].
{{Harmonics in equal|420}}


In addition, in the 29-limit, only 11 and 17 have step correspondences coprime with 420. This means that all other approximations are preserved from smaller edos, thus enabling EDO mergers and mashups.
=== Subsets and supersets ===
420 is a largely composite number, being divisible by {{EDOs| 2, 3, 4, 5, 6, 7, 10, 12, 14, 15, 20, 21, 28, 30, 35, 42, 60, 70, 84, 105, 140, and 210 }}. For this reason 420edo is rich in modulation circles.  


=== Regular temperament theory ===
== Trivia ==
420edo can be adapted for use with 2.5.7.11.13.19.23 subgroup, and it works satisfactorily with the 29-limit as a whole, although due to over 25% error on some harmonics, it's inconsistent. In the 11-limit, it notably tempers out [[4000/3993]], and in the 13-limit, [[10648/10647]].  
The approximation to the third harmonic, which derives from 70edo, constitutes 666 steps of 420edo. Nice.
 
=== Harmonics ===
{{Harmonics in equal|420}}


== Music ==
== Music ==