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Original Message

help with ella hum

Posted by tokyofist on March 15, 2006 at 18:42:23:
i've had my ella up an running great for about a week. last night i figured i'd go back under the hood and see if i could reduce the tiny bit of hum that was present (my speakers aren't super efficient - only 91db).
so i redid some of the grounding points on the rca inputs, rerouted the el34 heater wires away from the leads to the OPT, and checked a few other solder joints. i got everything back together - measurements were spot on. but, oh golly, is there a hum now (no source connected and volume all the way down). it sounds more like a weed wacker! the right channel seems to be much worse than the left, although both are unlistenable.
immediately, the changes that i made are suspect. i've looked them over once and everything seemed in order. i will go back over them again tomorrow when i have time to work on this. right now i'm just seeking suggestions/guidance for potential culprits so i can check multiple spots at once.
FWIW, here are my measured values:
pin5 to ground on EL34s = -50 VDC
EL34 heater wires = 6.58-6.60 VAC
middle tube heater wires = 6.28 VAC
B+ = 449 VDC
bias voltage is holding steady at .45 VDC

Thanks for any assistance!
dave