@LegionofDoom mentioned to me that his amp has a little bit of 60 Hz hum when music is paused. I have the same issue. It was present before I did the coupling cap mods, and it is there regardless of what tubes I’m using (I’ve replaced them all in multiple configurations, and it’s aways there. It’s not bothersome when listening to music, but I’m sure there would be a subtle improvement to detail and soundstage if this were corrected. Another quirk I’ve found is that it seems much more noticeable with low impedance headphones. A little digging online has me thinking it might be a result of DC coming through my mains. I stuck a multimeter in an outlet and I have about 58 mV of DC on the line, which might be too low to have an effect, but then again this is a very sensitive piece of gear, so perhaps…
Anyway, I was thinking of getting a filtering device. Pine Tree Audio makes custom linear power supplies and other esoteric electronics for audiophiles - they were recommended to me by Geno at Geshelli Labs when I was looking for a linear power supply for my soon-to-arrive Dayzee DAC. They have a power filter with a DC filter and AC noise filtering with fancy meters, etc. for $1,100, which seemed a little high to me for an uncertain possibility of fixing this one problem, so I am waiting to hear back from Jessie over there on a quote for a bare-bones version with all of the filtering, but a more basic case and no monitors, as well as a quote for straight up DC filter. I also saw this one, but I’m not ready to gamble this much $ for something I’m not sure will help…
https://upscaleaudio.com/products/i...sCCyS4wdoj1_u0hjbgZZd2m_cFn9OrgRoChxwQAvD_BwE
I’d be curious if anyone has any thoughts / insight on this. Either way, it’s sounding so good, I won’t be bothered if I can’t fix it. It’s in one of those spots right now with this tube set that I keep thinking of things to listen to, but I don’t even want to switch off the random tracks coming on after each song
I have had a few humming issues on my WA22 in just over eight years of ownership. Off the top here is what happened and what fixed it.
I should preface this with deoxit to clean all tube pins before they get near my amps. Even for the newest of new production. I learned this with my older WA6. Its pays...
Also, these issues aren't unique to the WA22. They go with the territory of using tubes... I have a McIntosh MHA200 that had many instances of the dreaded red plating and hums over two full sets of McIntosh branded tubes... new production, right out of the box. Fixed with tubes sourced from different manufactures. On to the WA22:
When brand new, low hum on both channels. Initially a power filter seemed to help. Longer term, no filtering and a different rectifier.
Next was a hum on one channel followed closely by a catastrophic failure of a new power tube. No damage to amp and tube vendor took care of the tube.
Next another hum on one channel followed by a failed driver tube. This was a favourite 7N7 in use several months. Again the vendor did the right thing helping out and the amp was fine.
Next a hum on one channel that was intermittent. Easy to identify it was a power tube... Several months in use and the vendor helped out again. Amp was fine.
This month alone, two incidents, low hum on both channels, a rectifier, that works with no noise on my WA6. Second event, hum on one channel, a driver, again one that works fine on my WA6.
On the flip side tubes that are noisy in my WA6 are good in the 22.
These amps are sensitive and lower impedance phones highlight any issue. They are old school designs that have been refined over many years. I suspect only a small percentage of owners have any issues and most are like what I have had. Given thousands of hours of use and enjoyment my WA22 has provided I look at the issues experienced as part of the fun this hobby provides. Little things to figure out and overcome. Tubes and their care and feeding. Many of us are running tubes that are seventy and even eighty plus years old.
Last thing I could offer is I run a very crowded listening station. Tons of equipment in a tight area. When I add a major component or do a major reorganization I have induced hums in various amps. Every time it has been solved by not allowing active power cords to run closely together in parallel or correcting an accidentally loosened connection. The appearance of disorder, in my setup, leads to musical nirvana. I run mid level interconnects but my power cords are stock junk!
I suggest asking Woo about that DC on your power lines. Check your cable runs and connections. Consider grounding. Double down on tube maintenance and combinations.
Worst case, find a dealer that will let you do an in home demo of the power conditioning kit they sell. Nothing worse than dropping coin on non solutions.
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