Hedgehog

Conventionally, Hedgehog (2.3.5.7[22 & 36c]) tempers out Jubilisma 50/49, splitting the octave in half into a tritone representing both 7/5 and 10/7, and the Sensamagic comma 245/243, equating a stack of two 9/7s with 5/3. If the subgroup is reduced to just 2.3.7, it tempers out the Stearnsma 118098/117649, resulting in a much more accurate temperament that can be extended in other ways.

g_

The 2.3.7 temperament is extremely useful in virtually any even edo with a decent 3, 7, and 9/7 due to its low complexity. Equating the difference between 9/7 and half an octave to 9/7 / (7/6) = 54/49 is an obvious thing to do because (9/7)^2 / (7/6) = 486/343 is 603¢. It is also obvious to equate 16/13 plus half an octave to 7/4. With this in mind, I propose two temperaments on either side of 22edo:

• The meantone version, 23-limit 36&50
• The straddle version (half-octave Porcupine), 23-limit 22&74bgh with alternate flat versions of 3, 17, and 19 at 11 generators away.