help with ella hum

Posted by tokyofist (A) 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

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Topic - help with ella hum - tokyofist 18:42:23 03/15/06 (27)

Re: help with ella hum - tokyofist 18:40:04 03/27/06 (0)

One step at a time. - PeterP 16:16:09 03/27/06 (12)

Re: One step at a time. - tokyofist 18:23:14 04/02/06 (11)

Re: One step at a time. - PeterP 17:51:44 04/08/06 (0)

Re: One step at a time. - Victor_A 16:05:19 04/07/06 (9)

Re: One step at a time. - PeterP 17:21:33 04/08/06 (8)

Re: One step at a time. - tokyofist 18:26:49 04/10/06 (7)

Re: One step at a time. - PeterP 05:11:35 04/11/06 (6)

Re: One step at a time. - Victor_A 19:12:58 04/14/06 (5)

Re: One step at a time. - tokyofist 16:44:29 04/15/06 (4)

Re: One step at a time. - PeterP 10:00:11 04/17/06 (1)

Re: One step at a time. - tokyofist 18:50:38 04/18/06 (0)

Re: One step at a time. - Victor_A 02:55:00 04/16/06 (1)

Re: One step at a time. - tokyofist 06:32:08 04/16/06 (0)

Re: help with ella hum - Graham 19:51:41 03/25/06 (0)

Re: help with ella hum - tokyofist 19:05:55 03/23/06 (2)

Re: help with ella hum - RHone 21:00:36 03/23/06 (1)

Re: help with ella hum - tokyofist 04:40:52 03/24/06 (0)

Re: help with ella hum - tokyofist 17:45:31 03/21/06 (0)

Re: help with ella hum - dave19 06:58:39 03/16/06 (0)

Re: help with ella hum - BillEpstein 03:05:29 03/16/06 (6)

Re: help with ella hum - tokyofist 13:55:48 03/16/06 (5)

Re: help with ella hum - BillEpstein 03:51:43 03/17/06 (4)

Re: help with ella hum - tokyofist 14:46:47 03/21/06 (3)

Re: help with ella hum - Victor_A 19:16:58 03/25/06 (2)

Re: help with ella hum - tokyofist 20:11:29 03/25/06 (1)

Re: help with ella hum - Victor_A 15:55:42 03/26/06 (0)

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