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White noise.

Posted: Mon Apr 15, 2019 11:20 pm
by Henz
after recapping my DRG, with same pedals in front, hiss increased dramatically. Any advice?

Re: White noise.

Posted: Wed Apr 24, 2019 12:41 am
by woodbutcher65
Voltages are higher, gain is higher. The amp is more sensitive, responsive, and dynamic. What you report should not be unexpected.

How is it with the pedals NOT in the loop?

You may have to adjust a few parameters to compensate for the effects of freshening the amp.

Re: White noise.

Posted: Wed Apr 24, 2019 11:32 am
by Don
I'd look at lead dress. Are any wires not laying in the same path where they were before the cap job?

Re: White noise.

Posted: Wed Apr 24, 2019 4:29 pm
by Henz
Thanks for the replies. Don, yes. I try to keep all leads neat and as close as possible to original place. I put in new other parts as well. I put a new 1000pf ceramic disc cap (C27) in lead circuit. The original had a pin hole in it. I read that , at times, the quality,manufacturer.... etc of new parts can introduce noise. I'm gonna put original back in to see if it helps. My voltages did go up. A lot on the plates. 524v without tubes. 512v with tube . Bias is ok. Within tolerance. LDR supply voltage, if I'm measuring at correct spot is 10v. EQ voltage is 63v . I'm measuring that off of the HV supply lead from power supply board to eq board. Not sure if that's the correct place to measure. My pedals do add noise indeed. But something happened that may change some things. Jim

Re: White noise.

Posted: Thu Apr 25, 2019 1:53 am
by Old BF Shred
Don’t own a Mark series amp, but just a shot....512v seems high.....6L6 is rated for 500. Yikes. Do you get any crackling/popping noise with it? May want to check balance (bleeder) resistors (150k, I think) across the primary caps. If these are not soldered well or open, that could explain higher than expected voltages. Saw this in a DC2 I repaired...snap, crackle, pop and crashing sounds and unsteady voltages until I replaced bad one that had opened. Good luck!

Re: White noise.

Posted: Thu Apr 25, 2019 12:27 pm
by Henz
No. No cracking or pops. When I recapped, I recall measuring them . They read fine . I would have to lift board and remove them from circuit to re check. There's much more to the story. I accidentally sprayed canned air on preamp board when amp was live and had a mini explosion. Could be a gazillion things now.