Hum on Tube Amp - Can't find source

@jea48 since we are on this, any recommendations on tubes or suppliers?

12AT7, 7044, EL-34, KT77?

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.

Holmz,

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. 

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 

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

@jea48 mine is different.  Please click on the audio and video I just posted.

@atmasphere thanks!

@clearthinker thanks.  lets see what demonstrates...

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?

Video of Tubes Cycling

Noise - Cycling Hum

@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.

@blackbag20  who knows we already have “Our Lady of Blessed Acceleration”! 

Come to think of it, I always have my cell on me and my watch has bluetooth…? in addition to the alarm's cell.

@wsrrsw typing from Phone is always a challenge,  I appreciate your time!

I did try a long extension cord to an outlet which is on a different panel (I have 6 panels at home plus the main panel at the interconnection with the utility).  Problem was present

@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.

@atmasphere Thanks for sharing your knowledge!  I'll read more about it.

I have asked the power company to come test their system.  I hope they stick a tester to their lines before coming to see inside.  I'm afraid they might take the easy way out and blame the amps

@wsrrsw It ain't Hammer Time buddy!   Noise is present even without interconnects

@dpop thanks to you and all others staying engaged with my dilema. I’ve been at this for weeks.

"After powering up the amps, how long before the hum appears? Does the hum then remain constant for the rest of the time after it first surfaces, or does it come and go?"

It takes 1 to 2 minutes to manifest. Once it starts, it doesn’t go away

"...on all tubes at the same time?" That I can see on all EL34/KT77

I’m going to upload to youtube and post a link

@pinotnoir it is a dedicated line/breaker to the music room outlets.  These feed the head units,4 monoblocks and a projector.  Keep in mind, Everything but one tube amp is connected at a time as I try to find the problem.

I originally had dimmers (fancy wifi ones) which I took out and replaced with standard non dimmable switches (no dimmers in the whole house now).

As I remove more things from the chain, my mind circles back to what I can't remove: whole house surge suppressor (https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.grainger.com%2Fproduct%2FSIEMENS-Surge-Protection-Device-Three-19T314&psig=AOvVaw2Rhsn6b5q61wEg7Jj_-WGO&ust=1670625130078000&source=images&cd=vfe&ved=0CA8QjhxqFwoTCPC7jNuJ6_sCFQAAAAAdAAAAABAE); Generac ATS and alarm cell.

@dpop my house was built 5 years ago but the transformer has been there for years (i had the lot for 15 years before i built). Hopefully they’ll come check properly.

The surge suppressor: https://www.grainger.com/product/19T314?gucid=N:N:PS:Paid:GGL:CSM-2295:4P7A1P:20501231&gclid=CjwKCAiAs8acBhA1EiwAgRFdw5vydJ0e_aoebliMyysBdXlqJr17jYErMuOOzINNmRQI1B3De8g-EhoCJyIQAvD_BwE&gclsrc=aw.ds

Yes the SS amps are totally quiet. The hum starts when the amps start to put sound. I can hear it 12 feet away...

FYI, there is no mechanical noise on the amps. Just the noise coming from the speaker drivers

No changes with or without the projector plugged in.

@wsrrsw tried with Van Alstine Humdinger (for DC) but as described by FVA it only works to solve mechanical noise. I decided to try anyway. 
 

Also tried the iFi plug in things and even an old Tice thing (not the digital clock)  

waiting on a Zen Line Conditioner from Decware. 
 

Tomorrow planning on shutting down the alarm’s cell and wireless sensors. 
 

I went into the circuit breaker panel to confirm ground are properly connected. 
 

Next is taking amps to test at my office. 

what am I missing?

Well, I can confirm it is not the alarm (which BTW I have reconnected!)

@redhouse6 like a Triplite?

I have a ZLC on order but it takes time to get it.

@atmasphere they are 20 years old.

I just realized that the prior owner changed the input tubes to 12AX7 when the design calls for 12AT7.  Thus higher gain (if my limited knowledge of tubes is correct) than what the spec for my particular version of these amps calls for.

Could that cause the oscillation?  I ordered a couple of AT7s to swap.

Regarding the factory and I quote: The unit was biased and received a complete test.  Unit passed all factory specs.

@rhljazz Not treated.  Thanks for the suggestion

@papafrgog the closest access point is 20'away.  I disconnected all wifi and low voltage and it didn't improve.  Thanks!

@redhouse6 I agree, I'll try on another location before buying something else.  I have a collection of tools and tweaks which is getting expensive.

Hoping the upcoming input tube swap finds the issue.

@jerryg123 Can't confirm.  Good question

@dpop thanks for adding my comments and past attempts.  Those links are very useful !  The reviewer said they are dead quiet.  Hoping I get that

@hiend2 @donavabdear thanks for the input

@atmasphere Can’t wait to get the tubes here. In hopes of staying away of issues like you mention, I ordered them from Manley.

Sure hope that solves the problem. I have tried so many things and never looked at that detail. Sometimes the simplest answer is the best one.

I wholeheartedly agree.  Funny, one of my bicycles is an Orbea "Occam"

Thanks for all your insights.  I'll post results after replacing the tubes.

@zombiedad swapped the KT77 also swapped the 7044 and 12ax7 from one unit to the other.

I suspect that 12ax7 is the problem.  Speaker wires are AQ Rocket directional 18" long

@jea48 + @dpop

It looks like the one I posted.

Mine is a TPS3A111000 (no superseded by TPS3A111002)

https://mall.industry.siemens.com/mall/en/us/Catalog/Product/?mlfb=US2%3ATPS3A111002

Thus:

voltage code: 120/240V, 10,3W

100kA per phase

EMI/RFI filtering (sine wave tracking), Ground integrated monitoring, Protection modes L-N, L-G, N-G, L-l

(whatever all of that means!)

@zombiedad I should have some tubes delivered tomorrow for the swap.

Let's hear!

@dpop I sent it because when I received them they had non OEM inline fuse holders and one was DOA.  I spoke with the seller and agreed that they should go to Manley for repairs/return to original configuration and any other repairs.

I paid for checkup and a couple of tubes that had the key broken.

Manley have been great.  They have followed the journey on this and offered suggestions.  The non conforming tube was brought up by them today/yesterday.

I did try with my other speakers (Aerial 8b) and noise is present. 
 

thanks for the info on tube testing!

I’ll read that Audio Asylum post now. 

@jea48 UHUM.  I didn't order the 7044 from Amazon.  Only a 12AT7 as a tester (TungSol) while the good ones arrive from Manley (7044 and 12AT7).

@dweller regretfully they did not.  The spec'd tubes for the Snapper changed and they now use the 12AX7, my vintage didn't.  Occam's Razor

Monday morning update.  I couldn't wait for the "good tubes" to come for testing.  I ordered one from Amazon (overnight delivery!) and the noise is completely gone.  Its scary quiet!

I ordered new 7044 as one of them is not up to par (still some noise).  I moved the 12 AT7 from one amp to the other and there was noise on the other amp; moved the 7044 from the quiet amp to the other and the noise is gone.

Huge lessons learned:

- there are a lot of enthusiasts out here who are willing to help

- @atmasphere is an awesome resource 

- start with the basics; I have spent weeks and $$$ chasing after the noise and never thought to check if the prior owner had used the proper tubes

I'll post again once both 7044 and 12AX7 have been replaced with the 12AT7.

Please accept my most sincere thanks for your help (and for the humor...  trolling with the motorboating sound...!)

we need a "Like" button on this forum

Yes, with the significant other "quarantining" due to Covid, I moved to the music room since last Monday!

Have put hours enjoying music!

The (financial) downside is that i hit the vendors:

- Have 2 quads of EL34's scheduled for delivery today.  With those, every single tube on the amps is new

- Waiting for the PS Airlens to be released so in the meantime I ordered (and received) a Wiim Pro

- Ordered a budget DAC to go with it (Topping D90SE MQA) which should be delivered later in the week

Currently running the Wiim to my trusty but dated spec'd Theta Gen V and alternatively to the onboard DAC on a Lexicon MC-1.

Have to say, the Wiim sounds good!  On A/B tests from my CD transport to the same DAC there is a discernible difference (improvement).

merits repeating: "atmosphere: This is why it can be so important to use the tube for which the amp is designed."

ha ha ha. I dont own a gravel but own 3 Orbea mountain bikes N+2