RE: UPDATE -One Channel Hum Affected by Volume - mr9iron - Vintage Asylum

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RE: UPDATE -One Channel Hum Affected by Volume

In Reply to: One Channel Hum Affected by Volume posted by mr9iron on March 28, 2025 at 00:59:55:

Just wanted to post an update to this post.

I was finally able to isolate the issue and fix it. It turns out I was right on top of it. There is RF getting into that channel and it definitely was in the pre amp section of V102.

In a previous response somewhere in here I mentioned that I changed out the preamp cables to higher quality ones and it slightly improved. I did some poking on those same cables with my phenolic probe and noticed shifts in the hum and I could even get the other channel to act up. -Strange I ran the cables exactly the way the original ones were.

I pulled them and cut new ones, re- routed away from the pre amp tubes and the diode ground that ran under under them. The new lengths are actually longer but take a new route into the 6u8's by running closer to the front of the amp near the control's VS near the "powered" stuff.

The shields at one end were grounded but I made a better effort to tin them and connect to the ground point (same ground as the pre-amp tubes)

Powered up and very good results, slight hum but very acceptable for a vintage unit like this. The only thing that confuses me is that those cables were original to start with and I ran the new ones the same way as the stock ones, nothing in that area changed physically. I can only surmise that the other changes to the PS and the new components created a new RF source.

thanks all,

Jeff

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Follow Ups Full Thread

Topic - One Channel Hum Affected by Volume - mr9iron 00:59:55 03/28/25 (10)

RE: UPDATE -One Channel Hum Affected by Volume - mr9iron 15:37:52 04/15/25 (1)

Thank you for the update - 1973shovel 11:27:27 04/17/25 (0)

RE: One Channel Hum Affected by Volume - mr9iron 00:35:12 04/01/25 (0)

RE: One Channel Hum Affected by Volume - DaveV 21:02:52 03/29/25 (1)

RE: One Channel Hum Affected by Volume - mr9iron 00:45:49 03/30/25 (0)

Here's a thought ... - J. S. Bach 09:43:57 03/29/25 (0)

RE: One Channel Hum Affected by Volume - 6bq5 12:14:39 03/28/25 (3)

RE: One Channel Hum Affected by Volume - mr9iron 12:47:43 03/28/25 (2)

RE: One Channel Hum Affected by Volume - 6bq5 15:05:15 03/28/25 (1)

RE: One Channel Hum Affected by Volume - mr9iron 15:28:08 03/28/25 (0)

Follow Ups

RE: UPDATE -One Channel Hum Affected by Volume - mr9iron 15:37:52 04/15/25 (1)

Thank you for the update - 1973shovel 11:27:27 04/17/25 (0)

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