On 2009-05-05 03:55:40 -0600, Ian Jackson
said:

In message 200905041533558930-joseph@removespamkirtlandcom, Joe Bento
writes

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Hum-wise, would there be any advantage in reversing the order of the
heaters for V1, 2 and 3, thus having the lower AC voltage at the lower
signal level stages?

Ahhh.... I need to change the designations on the schematic. The
12AT6's are at the ground side of the string as wired in my amp.
Though not nonexistent, hum is very low level.

Joe

Corrected schematic to show actual wiring of heater string. First
12AT6 preamp heater is closest to ground.

In message 2009050508580977923-joseph@removespamkirtlandcom, Joe Bento
writes
Corrected schematic to show actual wiring of heater string. First
12AT6 preamp heater is closest to ground.

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This arrangement might also help with reliability. The heater-cathode
breakdown rating of a 12AT6 might not be as high as a 50C5 (but I
haven't checked).
--
Ian