New Soul Sister pre

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New Soul Sister pre

Posted by calsaint (A) on February 20, 2017 at 15:13:45

I tore apart a few projects to build a Soul Sister.
It was a fun build, but there's a headache I'd like some help on.

800VCT, 200ma xformer, 5u4g rectifier
CLCLCRC (1.9u,50h,47u,50h,47u,820r,50u)
3300r leading resistor into series 0D3 for 300v at top of CCS
5670 tubes running at 9ma each, B7/15k, BCP-15 chokes, 50k Khozmo monos, I separated with an umbilical the PS and the pre between the 47u and 820r.

So the first problem was the voltage after the rectifier I had to bring down to get to 510v which is still more than I wanted.
I wasn't properly budgeting in PSUD the higher voltage from my house and the low draw from the circuit. I fiddled around with the first cap and the leading resistor and all that and eventually got it together and have good voltage leading into the regs and ~20ma dumped by the 0D3s.

Ultimately, my issue is that after around 2-5 minutes of play, a nasty buzz starts in. Do the experts here think that's the transformer, the rectifier, or the choke(s)? I'm no expert (clearly), but I've built a number of things from kits and schematics and have not experienced a buzz that emerges after warmup like that.

Thx
-Steve

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Topic - New Soul Sister pre - calsaint 15:13:45 02/20/17 (15)

Buzz after Warmup - Triode_Kingdom 12:36:01 02/22/17 (2)

RE: Buzz after Warmup - calsaint 17:22:56 02/22/17 (1)

RE: Buzz after Warmup - Triode_Kingdom 21:22:23 02/22/17 (0)

RE: New Soul Sister pre - drlowmu 08:04:54 02/22/17 (5)

RE: 15h, LL1673 - calsaint 17:28:28 02/22/17 (0)

RE: New Soul Sister pre - maxhifi 10:13:20 02/22/17 (3)

RE: New Soul Sister pre - drlowmu 17:22:41 02/22/17 (1)

RE: New Soul Sister pre - maxhifi 19:42:11 02/22/17 (0)

RE: New Soul Sister pre - calsaint 17:21:13 02/22/17 (0)

Most likely it is that first 50H choke. - Chip647 16:36:43 02/20/17 (5)

RE: Most likely it is that first 50H choke. - calsaint 09:08:34 02/21/17 (3)

RE: Most likely it is that first 50H choke. - maxhifi 11:07:56 02/21/17 (2)

As for the transformer and the 5u4g it's what I had around from an old build. - FenderLover 19:15:22 02/21/17 (1)

RE: As for the transformer and the 5u4g it's what I had around from an old build. - calsaint 17:16:27 02/22/17 (0)

Was there a reason for using a 5U4GB rectifier? - FenderLover 18:51:22 02/20/17 (0)

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