Tube amps picking up electrical pulse in my home. Any fixes?

I have a couple of different tube amps and a couple of SS ones too.

The tube amps seem to pick up some kind of static dull pop sound which is rather irritating.
It's not a consistent thing, the distance between pops varies.
If I disconnect the CD player, turntable etc from the amps, I still have the problem.
I don't have this issue with my Solid State amps.

Is there anything I can do to remedy this?
I don't really want to go through every electrical appliance in the house to find out what the cause is, but I'm wondering if there is a simple solution that would fix this for me?

 

Since this is happening with several amplifiers, and apparently not solid state, my take is it has something to do with the input impedance of the tube amps being considerably higher. This may well allow noise impinged on the interconnect cable from the preamp to get into the amp. It might be swamped by the lower input impedance of the solid state amp(s).

So this could be a shielding issue and where the interconnect cable is routed. A more shielded cable might not pick up the noise as easy for example. So I would try a different cable, different layout or maybe an input resistor in parallel with what is normally there in the tube amp (typically 100,000 ohms) so its input impedance is the same as the solid state gear (typically 10,000 ohms to 30,000 ohms).

It could also be a coincidence- the noise might be getting into the tube amps through the filament circuit of each amp and each amp has the same susceptibility. If this is the case, elevating the filament circuit (which involves the installation of a simple circuit to 'bias' the filaments at some voltage above ground, maybe about 60-80 volts) might do the trick.

 

From the simplest on to more difficult...
1. Rotate the AC plug in the wall socket 180 degrees. Use a cheater plug if your amp has "polorized" ends.
2. Run a dedicated ground from the amp chassis to earth gound (cold water pipe)
3. Run a dedicated line from the fuseblock to the amp(s)

These are not a guaranteed fix, but may in fact help out. My old SIlvertone stereo amp from 1958 benefitted from the first 2. Enough that I stopped there.

 

I forgot to mention, they're all integrated amplifiers.

 

Fixes? Yeah, go with Solid State!

 

There's always one!!!

 

LOL there is MORE than one, I promise you!

And I only did it to be a smart a$$ and someone had to do it!!! Plus, I have owned (and still own one) tube gear, I have nothing against tube or solid state, one of the reasons I opted for solid state this time was more time and no tube costs.......... I may end up with tubes again some day!

 

I agree with the cheater plug - try that - if that cleans it up - then buy a HumX device - which is a safe cheater plug. I use two - one each for my mono-blocks.

Also - build your own high quality directional interconnects (shield connected at one end only) - I've found my hum issues greatly reduced with my homemade interconnects - but not completely (better than my old RCA interconnects BJean)- so I still use the HumX device for complete black background - no noise at all.

 

Sadly we don't seem to have the HumX device here in the UK, it's for US voltages only.

 

Oh, you are from the UK, so your mains are not polarized. (117 VAC here in the USA is polarized) So, reversing the AC plug will make no difference. You could try running a chassis ground wire to a known ground, but I don't think that will help this particular problem. The source of the pop is electromagnetic (RFI or radio frequency interference) from an appliance, such as a refrigerator, or furnace relay. The best method of dealing with that is to upgrade your interconnects to full shielding, or double shielding. As @Ralph Karsten mentions, a higher impedance input is much more susceptible to RFI, so extra shielding should stop it.

 

See if the pop coincides with your fridge motor turning on.
Edit - I see The FRiNgE just mentioned that.

 

I have tried unplugging all interconnects from the amps and the noise persists with the amp running without anything hooked up to it.
It seems the problem is already there, even before the interconnects are in the chain.

 

If you are just having some pops - w/o doing anything at all - then it is most likely the tubes. You will have to rotate in some new tubes to determine which tube is making the noise - you can tap a tube with a pencil eraser to see if the sound comes more out of a specific tube.

I have mono-blocks so it is easy to rotate tubes from a quiet amp into the non quiet amp to find the culprit.

 

Excellent, this reduces it by process of elimination... the tube receiver may have a broken chassis/cabinet ground (as the cabinet shields the circuits from RFI) or the cabinet perforations/vents are allowing enough RFI through to be audible. The last suspect would be from the outlet, or through the amp's power supply.

 

If the issue is one of those, is there anything you'd suggest to solve the issue?

 

I understand you are not intent on troubleshooting appliances in your home. I must mention that a bad relay diode or cap (furnace relay box or the Fridge, or AC unit) can send a high voltage spike through your house wiring. The source of the pop could be from a high voltage spike, and this isn't good for any appliance plugged in your outlets. My suggestion is to have an electrician hook up a voltage recorder (or purchase one from Amazon) to eliminate this possibility.

 

LED bulbs or a ballast on the same circuit is noisy as hell every time I hear it.

 

Are both of the tubes amps from the same manufacturer? Same design? Do both of your tube amps have tube rectifiers or do they have a solid state rectifier circuit?

Can you add a line filter or a filtered power strip?

 

I used to get a popping sound out of my stereo system way back when I had a Nextel Phone. For whatever reason, my stereo would pick up an intermittent send/receive signal emanating from the Nextel. If you have cell phones in your house, try powering them all off, then see if you still experience the popping sound coming from your stereo...

 

When troubleshooting noise, there's really no substitute for things like going through the process necessary to find the cause. Doing it once will actually be a lot faster and a lot less frustrating than randomly trying a bunch of thing not particularly focused or directed at the problem in the hope that the problem will be solved.

It's hard to troubleshoot noise from afar. But based on what you've describe one set of guesses for likely sources could be nearby cell phones or wifi routers or other kinds of send/receive devices. Unplug or move all those kinds of things and see what happens.

Another possibility -- noisy tubes or poorly seated tube or tubes making intermittent, occasional, seemingly random static and pops could certainly result from these, though I wouldn't necessarily describe the sound from these as "dull," so maybe not -- still, with tube amps, problems often are the tubes (the do, after all, die and fail in the course of regular use like a light bulb). You could start by just pulling and re-seating all the tubes. Then if you're still getting the noise, try tapping on the tubes very gently with a wooden chopstick or a pencil with an eraser, if there's a crackling noise preamp tube, the tap test will usually reveal which one is the bad one.

 

My profile page has all my main gear listed if that helps. The amp has a tube rectifier.

The other amp is a vintage Rogers HG88 MK III amp from the 1960's, I can't remember if that has a tube rectifier or not.

 

If the amp lacks one, adding an across-the-line capacitor can help filter out electrical noise coming through the AC mains:

Safety Capacitors First: Class-X and Class-Y Capacitors

 

I have found a product which may do the trick...

Russ Andrews - Hi-Fi mains and cable specialist

They have a great returns policy, so if it doesn't work, I've lost nothing.
I think I might give it a try soon.

 

Dimmer switches can also radiate noise.

 

Actually this is what I did. I had a similar problem with my tube preamp/SS amp. After trouble shooting and doing my due diligence (brought a power conditioner, power strip moved things around till I was blue in the face), I went with a SS phonostage and integrated amp. It was the best decision that I've made, things are quiet and I'm no longer a hostage to tubes. If I need or want to I can change the sonic signature of my system by changing the interconnects.

M~