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Jacks and jumping jacks to the 13 limit

🔗genewardsmith <genewardsmith@juno.com>

2/20/2002 6:45:26 PM

I obtained the following list of jacks--superparticular ratios which are ratios of two 13-limit consonances, but which are not themsevles consonances for the prime limit they define:

169/168, 144/143, 121/120, 100/99, 99/98, 91/90, 81/80, 78/77, 66/65, 65/64, 64/63, 56/55, 55/54, 50/49, 49/48, 45/44, 40/39, 36/35, 33/32, 28/27, 27/26, 26/25, 25/24, 22/21, 21/20, 16/15, 15/14, 10/9, 9/8

Superparticular ratios of jacks now give us the following jumping jacks:

9801/9800, 4225/4224, 4096/4095, 3025/3024, 2401/2400, 2080/2079, 729/728, 676/675, 625/624, 540/539, 441/440, 385/384, 352/351, 351/350, 225/224, 176/175, 81/80, 64/63, 28/27

We might note the following:

(1) Some superparticular commas of importance such as 126/125 and 243/242 don't make the list, but see (3) below.

(2) A number of interesting temperaments (eg, miracle, orwell,
72-et, 31-et etc.) have a basis consisting of jumping jacks--in other words, they can be obtained as wedge products of jumping jacks.

(3) 123201/123200 = (351/350)/(352/351), which I dissed for not being a jumping jack, turns out to be a triple jack--the superparticular ratio of two jumping jacks which is not itself a jumping jack. Others of that ilk include 126/125, 4375/4374, and 243/242.