Filament supply with no center tap

Posted by banpuku (A) on February 22, 2017 at 13:17:28

I am trying to eliminate the dedicated filament transformers to free up some room in the chassis and utilize the taps on the power transformer. So, on my power transformer, there are 2 x (2.5VAC 3A) taps. I would like to use these in lieu of the dedicated filament transformers that I currently have. The dedicated filament transformers have a center tap.

I tried connecting the power transformer 2.5VAC taps and while I do get 2.5V at the 2A3 tubes, I get no music. Is this because I need a center tap or in this case, a derived center tap by using 2 resistors tied to ground? If so, is 1k ohm resistors the typical value to use? I was using 1k on the dedicated filament transformer center tap. Also, I am trying to avoid using a potentiometer.

Any input would be appreciated.

Thanks, Pat

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UPDATE 2/23/17

Thank you for those who responded. I have implemented the "AFTER" schematic listed below. I will perform some critical listening to determine what sonic impact this had vs. the original dedicated filament transformers. IF there is no adverse impact, then I will free up the space within the chassis by completely removing the filament transformers. There appears to be little to no hum. I will measure shortly. At this point, no need for a potentiometer. Thanks again. Pat

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"BEFORE" SCHEMATIC

"AFTER" SCHEMATIC

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Topic - Filament supply with no center tap - banpuku 13:17:28 02/22/17 (28)

RE: Here's a reworked schematic - sideliner 08:29:39 02/23/17 (12)

RE: Here's a reworked schematic - drlowmu 17:52:18 02/23/17 (11)

RE: Here's a reworked schematic - banpuku 07:37:03 02/24/17 (1)

RE: Here's a reworked schematic - 91derlust 12:58:42 02/24/17 (0)

RE: Here's a reworked schematic - sideliner 06:41:17 02/24/17 (0)

Good pick-up Jeff. - 91derlust 18:47:42 02/23/17 (7)

RE: Good pick-up Jeff. - banpuku 07:45:22 02/24/17 (6)

RE: Good pick-up Jeff. - drlowmu 08:45:35 02/24/17 (0)

RE: Good pick-up Jeff. - Lew 08:07:00 02/24/17 (4)

RE: Good pick-up Jeff. - banpuku 08:30:57 02/24/17 (3)

RE: Good pick-up Jeff. - drlowmu 08:53:20 02/24/17 (2)

RE: Good pick-up Jeff. - banpuku 09:49:19 02/24/17 (1)

RE: Good pick-up Jeff. - drlowmu 10:15:12 02/24/17 (0)

RE: Filament supply with no center tap - Michael Samra 05:38:53 02/23/17 (3)

RE: Filament supply with no center tap - banpuku 15:17:06 02/23/17 (2)

RE: Filament supply with no center tap - Michael Samra 11:32:57 02/24/17 (0)

RE: Filament supply with no center tap - drlowmu 16:18:20 02/23/17 (0)

Please, it's time learn tube basics. - 91derlust 23:19:55 02/22/17 (0)

RE: Filament supply with no center tap - drlowmu 17:19:34 02/22/17 (0)

10-ohm pot with two 20-ohm fixed on each leg - FenderLover 16:39:15 02/22/17 (1)

RE: 10-ohm pot with two 20-ohm fixed on each leg - 91derlust 23:54:39 02/22/17 (0)

RE: Filament supply with no center tap - vetmedrobert@gmail.com 14:42:12 02/22/17 (0)

100K ? - gusser 13:27:26 02/22/17 (5)

RE: 100K ? - banpuku 13:29:23 02/22/17 (4)

RE: 100K ? - gusser 13:32:34 02/22/17 (3)

RE: 100K ? - banpuku 13:34:52 02/22/17 (2)

RE: 100K ? - gusser 13:46:17 02/22/17 (1)

RE: 100K ? - Tre' 17:05:08 02/22/17 (0)

Filament supply with no center tap

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