Hum on Tube Amp - Can't find source

I have a hum (60hz) I can hear on my speakers and it happens with my tube monoblocks (either of them).  With or without interconnects, it even happens on either amp (have tried one at a time) with every circuit on the house tripped/disconnected, every other component disconnected from the wall (including the Internet/CaTV line) and no interconnects.  

One amp has it as soon as it warms up whereas the other one is intermittent.

Hum X doesn't solve it, iFi Ground defender either, AVA HumDinger on powerline  doesn't solve it either.

I have replaced the tubes and both amps were just tested at the factory.  Replaced the circuit breaker, tightened every wire on the breaker box, checked and cleaned all connections to ground rod.  Added a hum eliminator to the internet line.

Hum cycles a bit with the tube glow matching the cycles.

I'm waiting on the power company to come check the power coming to the house.



Have you tried using a cheater-plug? It removes the ground from the circuit, this will check for a ground-loop.

Thanks for input! Yes I have. Cheater plug, HumX ground loop eliminator, iFi ground defender. Noise still present.

happens with interconnects out of each or either monoblock.

cables are lifted, separated. No dimmers on the home.

Sounds like you have exhausted possibilities. Anyone who doesn't know what a HumX is unlikely to suggest any real solution. HumX works about 75% of the time for my unrelated issues.

Good luck. Are they noisy at any other locales? Hard to believe that they are at the factory. Proof?

I had a nasty intermittent hum / noise that was hard to track down.  It turned out to be a Glade Plug in air freshener..... you never know.

You don’t have the monos on separate receptacles, do you?

Any routers or wifi nearby? Dried out capacitors in amp power supply?

If you can disconnect everything and the amp still hums, I'd try a different amp.  Make sure it isn't the speaker that has the hum.  You've pretty much eliminated everything else.  

I guess you could put a power gneerator upstream such as a PS audio.  For a tube amp the Setllar 3 can be very affordable.


There’s something going on if it’s happening to both of your amps.

A few weeks ago, my wife was in the basement and turned on a space heater. A while later, I turned on my integrated upstairs and it started to hum. It had never done it before and I had no idea she turned on the heater. It took me days before I figured out what had happened. I had to call the manufacturer.

They called it DC Coupling.

Do you have led lights?  Even Xmas lights can cause a hum.


If nothing is plugged in (ICs) then it would be difficult to get a loop, so difficult to get a ground loop.

A DC bias on the AC line, usually comes across as transformer hum.
I ‘m not sure how it would come out of the speakers though.

Only thing I cannot disconnect is the power meter and a whole house surge suppressor that is right after the power meter. I have a standby generator but it’s isolated when there is power by an automatic transfer switch. 

all lighting are LED but the noise is present with all circuit breakers (but the amps) tripped. 

I have no hum on my solid state monoblocks which share power outlets (for testing they are disconnected) and are located near by. 

Odd that it takes a bit to start. You see the glow of the tubes change. 

would speaker feedback do that? IRS Beta 



I just tried VanAlstine humdingers on each and the problem persists. Please note, there is no mechanical hum on the amps; I have noise on speakers and the changing glow on the tubes. 

Dunno… multiple tap points on the amp?
Changing glow is not encouraging, but it is useful.

Some tube expert might chime in. Like Atmasphere if you ask him nicely…

You might want to try these amps in a different location to see if you get a different result, but I doubt you will. Even though the amps have been recently checked, they sound suspect to me. Many an amplifier or vacuum tube set have passed a bench check only to suffer some shipping damage on the way back to the customer.

What kind of amplifiers are they?

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Could you take an amp to a friend’s house and insert it in their system?  That would answer whether it us the amp or something in your house’s power system.  

MF’s article in Stereophile about the generator he installed would lead me to suspect your “automatic transfer switch”.


Maybe for you. Maybe... Any time I’ve tried a HumX I’ve followed negative results with a physical "cheater."

NEVER different for me.

Your assertion is easily proven with making a YouTube video.

The only thing I can think of, if you haven't done so already, is to disconnect the cable from your TV cable box or TV itself and also the modem to eliminate any effect it could have.

I had your situation and the hum ended up coming from my TV cable.  Attached a Jensen VRD-1FF CATV isolator and it took care of my problem.  However, I had my cable box L&R audio feeding into my tube preamp and as I remember using a cheater stopped the hum.  But worth a try.

take them to a friends house.

no input needed, just hook to speakers, plug in:

hum? it’s the amps.

if amps, analyze differences if any l/r time before hum starts? time hum changes?

no hum, it ain’t the amps.

go from there with confidence it is or is not the amps.


btw, have you hooked them up to an easily movable small set of speakers, different 2 way crossover, any difference?

Amps are Manley Snappers

will try with my Aerial speakers and see. After that, going to call on a neighbor and bring them in

i ran a long extension cord to an outdoor outlet and problem persisted


I installed a ground trap on the internet line. Going to disconnect it outside the home to take it out of the ground circuit

is there a link to the Stereophile article about the transfer switch?

thanks to all

Had this problem with a Primaluna Prologue Premium and Klipsch LaScallas.

Sent amp to Upscale Audio (Indianapolis to L.A.) who checked out the amp and said it was working normally.

Never fixed the problem so I sold the amp.

I believe the problem is/was in my main panel but didn't want to hire an electrician.

Doesn't affect my current equipment. Good luck.

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Get yourself something called a Digital Voltmeter. Set it to the AC scale and plug the probes into your AC power. Keep an eye on the voltage; when the hum shows up look at the voltage and see if its changed.

Or you could also use one of these:

The nice thing about this item is it can also measure the current drawn by an amplifier. It would be interesting to see what the current and AC voltage are doing when the amp hums.

Thanks to all of you!

@jea48 none matches. Going to try to link a sound file and video.

@atmasphere I ordered that meter you linked.  I will try and report back.  I assume put it around the power cord to the amp?

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I’ve had a number of tube amps over the years, both integrated and headphone. By design, they all produced some amount of hum. Even though I love the sound tubes produce (which in stereo mode, rarely ever 100% correctly sum to mono in headphones), I couldn’t tolerate the hum (and I’m not referring to the physical or mechanical transformer hum) the amps produced. I no longer have the patience for tubes. I personally now prefer the low distortion and low noise floors solid state provides. I believe what you’re hearing @ervikingo is hum produced by the amps, and it has no relation to the quality of AC power you’re supplying it.

@dpop - My amps have no audible hum with my ear up against the speakers. My speakers are 98db/w efficient. All tube amps don't have hum problems, and all solid state amps are not hum free.

@rocray Yes I have.  They have been great!  The amps went to them for an unrelated check up as I was resetting up my big system.  They found no issues with the amps other than a non-oem fuse holder (by a prior owner) which was removed and brought back to spec.

I have followed their instructions and it makes sense to me that it ain't the amps.

If it were, I could see one of them exhibiting the behavior but not both.

@ervikingo There’s been no mention yet of biasing. Have you checked it for all tubes? From the Manley Snapper manual, this is the rated Noise Floor spec: Typically 105µV = -77dBu A-WGT Typically 388µV = -66dBu unweighted. Depending upon how close your ear is to the speaker (inches away?), with that type of noise floor spec, my ears would probably hear some hum too (especially at -66 dBu).

Manley; The Snapper manual


My amps have no audible hum with my ear up against the speakers.

I’m glad to hear that.

All tube amps don’t have hum problems, and all solid state amps are not hum free.

I would agree with you. All of the tube amps I’ve ever owned, did (have a certain amount of hum). I prefer my noise floors to be in the -95 dBu area (exceptions being vinyl playback). With that in mind, I could never find a tube amp that approached that. I’m not saying they’re not out there, I just however gave up my quest trying to find one. When it comes to tube headphone amps, I also don’t like the fact that rarely have I ever heard one that sums to mono, correctly (like SS does) 100%. This matters when listening to any audio mix, as the mixing engineer many times will pan certain sources to center (mono). Many wouldn’t notice this, or care about it, but I do.


60Hz.   Has to be a mains hum.

Take all your kit to a friend's house and see if you have the hum.

If not, it's on your mains.  Get engineer in.

If it is still there in your friend's house then it's your kit.  Swap each item in and out and find the culprit.

QED.  Clearthinker OK.

I read an article and they said tube amps hum.  That would drive me nuts.  


I read an article and they said tube amps hum. That would drive me nuts.

Lucky you’ve never been there. The sound produced by tubes is many times euphoric, but that hum can drive some nuts (like me). IMO, sometimes there’s a trade-off with tubes. To get that liquidity, you sometimes have to also tolerate (ignore) the hum that sometimes goes along with it, or, if it is present, some don't even notice it.

My Aric Audio push-pull tube amp makes no noise whatsoever! The transformers don’t hum and I hear no hum coming out of the speakers. All tube amps do not hum!



Have you prayed to St. Jude? Problems like this are maddening.

When all other breakers were off is there anything else power on the Amp’s circuit?

When you play music does the hum audibly persist?

Did you get extension cords and try different circuits?


If not, it's on your mains.  Get engineer in.

Without anything plugged in it is unlikely to be a ground loop.

@holmz    I didn't say it might be a ground loop, although it may be.

If OP reports correctly the hum is exactly 60Hz, the coincidence is too much.

That's why I suggested to test the rig in another location.

@wsrrsw i haven’t yet but I’m about to. 

high end not “audiophile” outlets. 

Just tried again tripping every panel and breaker except for the amp’s outlets. Comcast line disconnected outside the home BEFORE the ground block (this nothing from Comcast is connected to the house). Nothing else plugged in and no interconnects plugged in. Noise remains. Connected to my Aerial speakers, noise present. Tried both amps, problem on both 

Has to be an issue with my wiring, the power coming into the house, the ATS, whole house surge suppressor or got lucky and have two separate amps with the same malady(and what are the odds of that?)

only other thing left is the cellphone of the alarm system which has a ups. It is located 20/30’ from amps. I wonder. 

@dpop Once the noise starts you can't bias them as the voltage cycles.  Having said that, they are right at 298-303 on all tubes (after many tries before the noise starts).


@jerryg123 Thanks, I read the article and the discussion about it here, on AK and other sites.  It was highlighted on a post before.  He describes a change in sound but not the noise I have present.  His solution was to add Powerplants.  I am hoping to address the issue before that kind of investment.