677edo
| ← 676edo | 677edo | 678edo → |
677 equal divisions of the octave (abbreviated 677edo or 677ed2), also called 677-tone equal temperament (677tet) or 677 equal temperament (677et) when viewed under a regular temperament perspective, is the tuning system that divides the octave into 677 equal parts of about 1.77 ¢ each. Each step represents a frequency ratio of 21/677, or the 677th root of 2.
Theory
While it does well as a 2.3.5.11 tuning system, it's notable for its high accuracy among EDOs of about its size and lower with the first several metallic ratios. Among those, it tunes acoustic phi (the golden ratio) and the acoustic copper ratio each with less than 1% relative error. The first nine metallic ratios are all tuned within 20% of an edostep.
Prime harmonics
| Harmonic | 2 | 3 | 5 | 7 | 11 | 13 | 17 | 19 | 23 | |
|---|---|---|---|---|---|---|---|---|---|---|
| Error | Absolute (¢) | +0.00 | -0.03 | +0.10 | +0.75 | -0.06 | -0.35 | -0.38 | +0.27 | -0.80 |
| Relative (%) | +0.0 | -2.0 | +5.5 | +42.1 | -3.5 | -19.8 | -21.2 | +15.3 | -45.1 | |
| Steps (reduced) |
677 (0) |
1073 (396) |
1572 (218) |
1901 (547) |
2342 (311) |
2505 (474) |
2767 (59) |
2876 (168) |
3062 (354) | |
Subsets and supersets
677edo is the 123rd prime EDO.
Regular temperament properties
| Subgroup | Comma list | Mapping | Optimal 8ve stretch (¢) |
Tuning error | |
|---|---|---|---|---|---|
| Absolute (¢) | Relative (%) | ||||
| 2.3 | [-1073 677⟩ | [⟨677 1073]] | +0.0110 | 0.0110 | 0.62 |
| 2.3.5 | [38 -2 -15⟩, [-31 43 -16⟩ | [⟨677 1073 1572]] | −0.0066 | 0.0264 | 1.49 |
| 2.3.5.7 | 703125/702464, 589824/588245, 14348907/14336000 | [⟨677 1073 1572 1901]] | −0.0714 | 0.1145 | 6.46 |
| 2.3.5.7.11 | 3025/3024, 24057/24010, 131072/130977, 759375/758912 | [⟨677 1073 1572 1901 2342]] | −0.0535 | 0.1084 | 6.12 |
Rank-2 temperaments
| Periods per 8ve |
Generator* | Cents* | Associated ratio* |
Temperaments |
|---|---|---|---|---|
| 1 | 109\677 | 193.21 | 262144/234375 | Luna |
| 1 | 125\677 | 221.57 | 8388608/7381125 | Fortune |
| 1 | 281\677 | 498.08 | 4/3 | Counterschismic |
* Octave-reduced form, reduced to the first half-octave, and minimal form in parentheses if distinct
Music
- "From the Ears of the Eel" from Scoop (2024) – Spotify | Bandcamp | YouTube
- "The Scallop Disco Accident" from The Scallop Disco Accident (2025) – Spotify | Bandcamp | YouTube – in Scarlattic, 677edo tuning
- "Make Gecko Expansion" from I Want To (2025) – Spotify | Bandcamp | YouTube – in Genzelic, 677edo tuning