Thanks gents. @Polygonhell i think youre like me on a sensitivity to noise scale. Youre probably better at blocking it out though and just enjoying.
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When I need to adjust the hum pots I will use my IEMs as they let me dial it in a lot better than with only the Utopia. Obviously if it is not related to the power tubes, the null pots won’t change any other noises popping up like a ground loop that I did have pop up when adding a component with a grounding issue.
@Souldriver I also am very sensitive to noise and have spent more time than I care to in identifying the culprits 
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Probably a good move. I didnt know dna stuff had hum pots.
Well i am glad i tagged you too then! A certified Hum Hunter!
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The stratus has ac heaters, for DHT’s with AC heaters they are pretty much unavoidable, your running an AC signal across the cathode of the tube, if the AC isn’t perfectly balanced at the central tap, you get that 60Hz signal directly on the output, hence trim pots.
EMF can also cause 60Hz hum and ground noise.
FWIW I also can’t entirely tune out the 60Hz hum on the Egoista with the trim pots, it’s at similar levels. The simplest solution for the Utopia is to use an output attenuator. I added one to my hybrid amp (not that it needs it to be silent) to give my more usable range on the stepped attenuator.
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Starlet was noise free with Utopia and Stellaris is noise free with Utopia and Mysphere 3.1, cave-like quiet, I sometimes check to see if I have the damn thing on. I sit right next to my rig so I can hear the faint hum of my gear but nothing translates through to my headphones.
The only time I had noise issues is very similar to what @camus pointed out already, either an external source of interference, bad tube or a rare 2a3 set I couldnt null out fully (Linlai 2a3). My biggest extraneous noise issues were solved by getting rid of my Holo May, moving the SMPS for my router and the power conditioner sorted out the rest.
Im pathologically sensitive to extraneous noise with my setup so it pleases me to no end that its extremely quiet.
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Sounds like the EC. I pause it for calls and forget i turned it on until i see the power light.
To peel back the curtain a bit someone noted they liked how the DNA amps sound but he thought they were noisy. I thought that was odd since its recommended for the Utopia and that will pick up most things. He heard it at an Axpona show and thinks it was either show conditions or maybe Donald made some revisions to since then.
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That’s huge assumption given his only experience was at Axpona, everyone hears differently and some think other tube amps don’t have a noise floor because they can’t hear it with the music playing. Surprise it’s still there in the background!
Also, Donald wouldn’t make a revision and release with a higher noise floor. Not sure where he got that assumption from, even on the prototype amps Donald send’s out he ensures they are up to his standard. In other words they are 99% complete amps with minor part change which the majority of folks would likely not notice.
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There is no way you’d hear the noise floor on the one I had with ANY ambient noise.
I’m lucky enough to live in an area where there is 0 traffic or neighbor noise, and the loudest thing in my house during the Spring is the frogs at the nearby lake.
As I said I had to listen for it and concentrate to hear it. I couldn’t have heard it in those conditions.
Maybe a bad tube, or something external interfering with it, hard to guess.
The big advantage the EC has from a noise standpoint is the separate power supply.
I could hear slight noise from my studio T when the PSU was right next to the main case, move it 1ft away and I can’t hear it anymore.
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I will say on my EC. I had them 3" apart and still nothing. I know some old moth stuff was said to have noise but it seems since then Craig made revisions and took any noise personally.
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Hi all, I am just joining per advice from a hi-fi friend. I am new to tube amps, and just took the plunge on a DNA Stratus v4 to drive Utopia 2022. Bought it from a seller who drove mostly Senns (and other less sensitive cans), and reported zero noise. I however am hearing a hum with either the stock Psvane power tubes, or Ken-Rads. Here is a list of all the things I have tried:
-swapped tubes
-removed amp from rack, reconnected it to power on an entirely separate outlet away from other equipment without any inputs other than power. Removed all tubes, then tested noise adding one tube at a time. First was input tube- no noise. Then introduced single power tube. Every time, regardless of channel or brand, I heard hum that I could not make go away using the hum pot.
Any thoughts/ theories? Suggestions? Other troubleshooting advice?
Thanks in advance!
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The trim pots will let you minimize it, I could never get my V3 entirely silent with the Utopia, I could get very close. The Utopia is just insanely sensitive.
Outside of that, you should test with not source connected, if it goes away with no source, it’s most likely a ground issue.
You won’t hear anything without the power tube, you can try it with the power tube and without the pre tube, but all that will tell you is if it’s the power or presection the noise is coming from.
How loud is the hum?
You can also probably contact Donald North, he is very responsive to email.
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@Daniel4IEM didnt you also mention it was mostly contained to only one of the channels but not both.
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Thanks for getting back! The test I described above was without a source connected, so the hum I hear from Stratus is not entirely due to ground issue (although I also have that problem but that’s another topic).
The hum at this point is pretty low (I can live with it I guess).
I am already working with Donald via email (yes, he rocks), but at this point we have kind of run out of troubleshooting ideas other than me sending it to him to investigate. Just thought I would run it past this group too for ideas
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right! Well, at least at first that was the case. After the step described below, the hum actually showed up in the left channel too. The one in the right was decreased, but still there. I am able to get it down to zero in the left hum pot now, but not the right one. I wonder if the hum pot is not working correctly?
-removed amp from rack, reconnected it to power on an entirely separate outlet away from other equipment without any inputs other than power. Removed all tubes, then tested noise adding one tube at a time. First was input tube- no noise. Then introduced single power tube. Every time, regardless of channel or brand, I heard hum that I could not make go away using the hum pot.
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Hello,
If you feel confident enough, check the socket.
But before you do that, remove the main fuse before dismantling it.
Often, there may be corroded contacts here, or even the cable itself.
Sometimes it can also be connected incorrectly.
Ideally, replace the socket with a Furutech socket; re-insulating the cable may also help here.
I’ve had this happen before: the socket had been painted over with wall paint, and the contacts were also affected, and behind the socket, the cables had been stripped too far and were partially corroded.
Once all that was fixed, everything was fine again.
I searched for a long time and tried many things.
In such a case, phasing out may also be important and can help here as well.
These are actually small things that can have a big impact.
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It’s just hard to diagnose sounds like hums over a forum.
It could be almost anything, from a bad solder joint to a picky tube, to a ground problem, to just EMF from the power supply or environment.
It’s VERY hard to get a single box amp using DHT’s completely silent on something as sensitive as the Utopia, and there is an element of what’s normal. I’ve seen lots of people claim their Stratus was completely silent, as I say mine wasn’t there was a slight (barely audible) hum in both channels on the Utopia, that I couldn’t null out with the hum pots.
I think working with Donald is really the only way this is going to get resolved for you.
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thank you, guys! At this point, I can live with it. Will continue to discuss with Donald, and if necessary send it to him
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Yeah but, how does it sound?
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You’re absolutely right.
It’s really difficult to diagnose something via the forum.
However, you could also say that a lot of it is self-inflicted, and if not, then something has been connected incorrectly in the house or flat.
This doesn’t usually apply to normal household appliances, as they still work.
But it does apply to sensitive devices that we use.
You won’t believe it, but when I moved out and my brother-in-law, who is an electrician, took down my lamp, he was puzzled and said that I had connected the lamp incorrectly, but that it still worked.
This can happen because the cables were from the old building and the new lamp uses the new EU cable colour standard.
In the end, it’s always little things like that. Even though a cable is a cable, the type of connection is crucial.
That’s why 80% of faults with such problems are often related to the user themselves.
I’ve seen a lot myself, from power strips extended to power strips and exceeding the wattage, to incorrectly connected sockets or sockets that were simply broken or faulty.
Overused power strips, defective power strips, sometimes it was just the switch itself. Electrostatic charge from the carpet, incorrect positioning of the devices.
It takes time to check everything, but it’s better to do so before you have to send it back, and if it has to go across the pond, it’s annoying when nothing can be found.
Personally, I think it might be due to the noise floor, where you can hear something through the Utopia.
If a 300 ohm or 150 ohm headphone is quiet, then I guess that could be the reason.
Maybe Donald can do something about it.
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out of this world! You were right when you expected it to blow my socks off. Now I know what “holographic” means 
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