Thread for the various Woo headphone and speaker desktop amps
How does wa22 perform? What is the sound signature and good synergies?
Quoting some WA22 chats from the source help thread to get you started (but yeah, click through and read the thread as well):
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That $2.5 ~3.5k price point for headphone amps is busy AF and hotly contended it seems.
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so I have a hum with my WA33, thoughts on how I can troubleshoot the source of the problem?
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One thing to note, your not supposed to leave it on without headphones plugged in.
But generally transformer Buzz audible without headphones is usually a result of bad power specifically a DC offset on the mains voltage.
Bad recitifier can also cause it, and it’s an easy test if you have the stock rectifier.
Do note however that It is relatively common for the amp to buzz on startup, but it should resolve completely after 5 or 10 minutes as it warms up.
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I need to play with the voltages on the back. It’s set to 120 at the moment if I recall correctly. I’m not home at the moment. Will definitely try the new rectifier I have compared to the stock one currently in.
It doesn’t stop after more than 10 minutes warming up.
Also, I’m aware of not running it without headphones. Trying to troubleshoot anything I can though so that’s why the video is without one plugged in.
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That’s not that bad as far as hum goes. Power is the first thing to look at like @Polygonhell said. The only other thing you can do is start swapping tubes. Short troubleshooting list unfortunately. An AC regenerator may be in the cards.
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So I have zero understanding of power and electricity. Can anyone tell me if there’s risk in changing this setting on the back to see if that helps? Obviously only changing when the device is turned off and disconnected from the wall.
Also, what’s a DC offset?
Just to confirm, you’re in the US? If so then it should be at 120. There’s no harm in trying it. But yeah, do it when it’s off and not plugged in. 
DC offset means that the AC lines bringing power into your home have some small amount of DC current in the line; the and AC transformers don’t like that so they hum.
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Is this specifically for Woo amps or a general rule for all tube amps?
I’d personally suggest keeping headphones plugged in/a load attached to most tube amps unless they specifically tell you it’s fine or you don’t have to. I’d really even suggest that with some solid state depending on the design, although bigger priority with tube stuff
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The woo is the only headphone amp I know warns about this.
Generally higher power transformer coupled tube amps might have an issue, the load of the headphone in reflected into the output stage (by design), and without it more current flows through both the transformer, and usually the cathode resistor as well as the tube. If either of those isn’t rated for the additional current, something will act as a fuse, either one of those components or if your amp designer has any sense a fuse in the circuit instead.
It is extremely common for high end high powered tube speaker amps to commit suicide if there is no load, mine blow the fuse, but if you had the wrong fuse, the amp would fry itself.
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As @dB_Cooper said, it’s something in your power, basically a small ammount of DC, sometimes it’s caused inside your house, but often it comes off the street that way.
The mains transformer doesn’t like it, and vibrates.
As I said it’s common on startup for a lot of equipment, but usually it goes away after 10 or 20 minutes, if it persists after that, you might need something to filter it out.
I’d personally plug in a pair of HD6XX or something and leave it on for an hour, your not going to hurt anything.
Isolation transformers are the usual fix, or regenerators.
But before you go buy one, I’d email Woo and see if they can tell you anything. It’s almost certainly not in warranty (they changed the terms recently, older stuff is original purchase only), but they’ve been responsive to my requests for information.
Thanks @Polygonhell and @M0N . I normally unplug my headphones and leave the amp on if I’m not going to be listening to anything, because I was more concerned about damaging the headphones by leaving them connected, in case there was a power surge or brown out. I’ll text Justin at Ampsandsound to get his thoughts on the Nautilus.
Switched rectifiers, it helped a bit but still a noticeable hum. I ordered this ifi DC blocker to see if that’s going to help: https://www.amazon.com/iFi-SilentPower-DC-Blocker-Connector/dp/B08XWHJRZ1/
Also going to try moving the amp around the house and switch the power cancel those reasons. I don’t have any other tubes to swap but the store that sold me the amp communicated a few times that they tested everything and I have no reason to believe it didn’t work flawlessly for them.
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I had the ifi dc blocker connected to my spring and it did remove ~95% of the dc offset problem, so works well if dc offset is indeed your problem
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it’s now 9:40pm and the amp is much quieter than it was in the afternoon. Still buzzing but incomparable to earlier. I guess this contributes to the idea that it’s power related?
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Yes power quality can vary dramatically by time of day, and even day of the week, noise is generally a function of what you and the people sharing the substation are pumping out in terms of back EMF.
Hopefully the ifi dc blocker can resolve it.
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Actually I’m assuming you have your spring plugged into the same outlet? If it’s DC offset then your spring should be humming as well (unless the woo is more sensitive to that kind of stuff)…
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