1590 = 200W
1594 = 100W
1593 = 50W

The "A" model was strange in that it used a positive ground power supply.

All of these power amplifiers were patterned after the tube amps with a multiple-tap output transformers. The 1594B offers output taps of 4 ohms, 8 ohms, 16 ohms, 25V and 70V. The input is routed through an octal socket for either a 15335A or 15095A transformer.

15335A = 15k input
15095A = 600 input with 14dB of gain (used for the end of long wire runs)