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AUDIO FORUMS >> D.I.Y. >> Reducing Power Supply Ripple in SE84UFO25
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Message started by Sam V on 06/04/23 at 23:16:35

Title: Reducing Power Supply Ripple in SE84UFO25
Post by Sam V on 06/04/23 at 23:16:35

I've noticed a quiet (but audible from my listening position, so I really would like to fix it if possible) 120hz hum from my SE84UFO25. Tried a bunch of other fixes (cables, power conditioning, etc etc), wound up talking to Steve, and he said this was power supply ripple. Any ideas on how I might be able to reduce this ripple? Swapping out the filter caps, or adding additional ones? Any/all thoughts/suggestions appreciated! Thanks!

Title: Re: Reducing Power Supply Ripple in SE84UFO25
Post by Carlsbad on 10/05/23 at 00:08:16

It isn't the power supply. The SE84 is designed with AC Heaters so you will always have a very minor hum. However, this varies a lot with tubes and the tubes that matter the most are the input tubes. I've noticed the russian tubes have more hum. I've got an Amperex bugle boy 6DJ8 in there now and almost no hum. the Electroharmonix was even quieter but not as good a sound.
Jerry

Title: Re: Reducing Power Supply Ripple in SE84UFO25
Post by dank on 10/05/23 at 12:17:11

I'm having trouble understanding how an AC heater could produce a 120hz hum...seems to me it would be 60 hz. If the problem really is 120 hz, I'd put my money on the high voltage power supply, or wiring, or magnetic field induced noise coupling and, unfortunately, I have no "off the top of my head" fix for this...wish I did! Less sensitive speakers? Move the listening position further back?

Dan

Title: Re: Reducing Power Supply Ripple in SE84UFO25
Post by Carlsbad on 10/06/23 at 01:48:48

Dan,
I think you are right. I guess if it is 120hz, it is from the transformer.

I did just start a thead in DIY about a transformer that advertizes itself as an upgrade for the Decware SE84 series amps. I know nothing about it and am hoping to find someone who has tried it.

Jerry