Never heard an amp do this before, ideas?

I have a primaluna 100 unplugged from any inputs. It has this awful high pitched sound coming from the speakers when it's turned on. It happens on both channels, and through headphones.

I have turned off all electricity in the apartment, turned all breakers off except the one it's on, moved the amp around the apartment, tried a humx, and different power cables. I even replaced the unit with another primaluna and they both do it.

I'm running out of ideas, anyone ever seen this before?



Call Kevin Deal at Upscale Audio, CA.  He is the importer/distributor and could most likely pinpoint what the problem is. 

Let us know what you discover. I’ve used a PL integrated for over 4 years and absolutely nary an issue. Mine is dead quiet.  Contacting Upscale is where I would start first.

bad power supply, a ground loop, or in need of further inspection.Test another amplifier to see if it's the amplifier that's the problem.

@mastering92 thanks for the advice, I tested two primaluna amplifiers, both did it. I also tried a cheater plug.

Update: wrapping a faraday blanket over the unit dampens the sound. But the source of the RFI is not from my apartment, because it happens with everything in the apartment unplugged and off.

Does this mean all tube amps will do this and I'll have to go SS? 



This is not a “tube” problem. Not sure what it is… but this is never problem with high end audio equipment. So, either it is a PrimaLuna problem or a location problem. I would not abstract this to tubes or good quality components.

When you say "apartment", it makes me think of multiple households and things that are beyond your control in those dwellings. Though you probably have separate meters, some god-awful faulty appliance or wiring flaw could be generating interference. 

Can you take it to a friend's home, Along with a pair of headphones and see if the problem exists away from your environment?

"I tested two primaluna amplifiers, both did it. I also tried a cheater plug."

This tells me not to waste time on the tubes or components in your amp, unless it does the same thing in a totally different environment. Heck, take it to work and try it there.

What's a cheater plug?


@mwinkc it's a (not very safe) bypass on ground, so you can rule out ground loop issues. I think you're right, it's environmental. Unfortunately I don't think it's related to electricity, it's probably radio interference. Because the only thing that made the sound almost go away was wrapping the thing in a faraday blanket.


The disappointing part is that I can't fix that-- it's probably coming from outside. So I'm wondering if SS will be as sensitive to RFI, or if I can get away with hybrid.

Take the amps to your local stereo shop to check out some speakers with it.  Gives you a reason to go listen to some speakers.  Maybe even to work with a pair of headphones.  Eliminate the environment.

You would not be using expensive speaker cables, would you?   I'm recalling back in the day, there were speaker cables that certain "tube" amplifiers did not like. Would set the amp into oscillation.  My idea was that the circuit were seeing a resonant tank circuits of their tubes, transformer and speaker cable. Try going back to zip wire or other cable. 

I second @jasonbourne52 suggestion. Does it make the noise when the inputs are connected to something and amp is powered on?

@oldaudiophile led lights on dimmers, a WiFi router, hvac, and refrigerator. A few switching power adapters plugged in throughout the apartment. Florescent lights in the bathroom.


All of these things are suspect to me, most are pretty far from the unit. I've shut down breakers and made sure lights/hvac/wifi/refrigerator are off without effect, though.


​​​​​​I'm in an apartment on the 4th floor in NYC. About 8 floors up is some Verizon equipment. Across the street there is a big service elevator.


part of me is thinking I should find a way to locate the RFI noise somehow, but I'm not sure how.

Do occupants of nearby apartments in the building hear the same with their stereos?

Bring the unit to another location and give it a whirl - I had something similar happen with a Mesa Boogie Dual Rectifier 4x10 "Blue Angel".  Ultimately in my situation there were two problems - one was RFI at my location (which was clear after moving the amp) and the other was a bad capacitor. A quick repair to address the 'singing cap' and we were good to go (especially once I moved to a new apartment and the amp had a friendlier environment).  Unfortunately, I sold the amp to pay for my first wife's engagement ring... woof, did I get it wrong with that one lol :D :D :D

Several years ago I was walking around my house, when all of a sudden two people seemed to have a conversation in my music room. I grabbed a hideout, and went in. Nobody there, then they started talking again. It was coming from a Mission 707S speaker I had sitting on my main speakers. Just as clear as a real person speaking to me face to face. Listening to the conversation, I discovered it was the local police transmitting back and forth from base to cruiser. I looked outside, and there was a marked car sitting in the parking lot of a Pizza Hut across the street. The speaker wasn't hooked up to anything, except for the wire hanging down. I guess it was acting as an antenna. Freaked me out! 

@hobbes101 Wish I had an easy answer for you. I understand the anguish. The reason I asked about electronic equipment in proximity to the amp is because of a similar annoying issue I experienced that turned out to be caused by a DirecTV satellite receiver. I guess those things are really poorly insulated. Even though it was a few feet away from my amp on the equipment rack, it was causing an annoying low level, barely audible hum I could hear through my speakers whenever the volume on the amp was turned up relatively high (music or no music playing). As soon as I got rid of DirecTV, problem solved! My WIFI is on my stereo rack's top shelf, about 3 feet away from my amp on the bottom shelf. No problem!  My 55" LG LED TV is right above my rack. No problem! I've heard of light dimmer switches causing interference. I doubt the rest of the things you mentioned could be a culprit unless the wiring in your apartment building is really ancient. Best advice I can think of is to higher an electrician (a really good/smart one) to come have a look.  Good luck! Just out of curiosity, I'd be interested in knowing what this turns out to be. Even with so called expert advice from a number of accomplished audiophiles, I had a devil of a time finally figuring out my DirecTV satellite receiver problem.

Does it happen on all inputs of the integrated amp?

What happens with a shorting plug in the inputs?

What happen with a shorting plung and the speakers disconnected? You will have to measure with a scope or good multimeter/

What are your speaker cables?

@ieales thanks for the suggestions, I purchased some plugs and I'll try that!


I have svs speaker cables, but it happened with headphones and no cables too.

i had the same issue with avr in past. the repair shop said they couldn't figure out where it was bad ground and the manufacturer sent me a replacement unit under warranty.

I have svs speaker cables, but it happened with headphones and no cables too.

Does the amp have a headphone jack and you hear it with headphones and no speakers attached?

Kind of off the subject. Is it not detrimental for tube amp not having a load (speaker connected) on the output while being turned on? From the video it looks like the speaker is connected to only one channel. I could be wrong, but I think it is a no-no.

@ieales yes, it has a headphone jack and I unattached the speakers, the sound comes through the headphones.

@knock1 I didn't know it's bad, but yes normally I have both speakers attached, I had been moving it around testing and wanted to make a quick video.

If your problem is RF interference (my guess) it is probably a misbehaving appliance at a neighbors. I once had my garage door refuse to work for a whole month, then all went back to normal.  

If you want to sleuth it out you can get a RF Dongle like this: RF Viewer — Low-Cost, Wireless USB Dongle, RF Spectrum Analyzer ( Once you find the misbehaving item it is within your rights to ask (demand) that they fix it. The FCC is the governing body so don't expect much help there. 

Call Kevin and let us know what he says. Most of us here are just guessing.  He should know.

& is it possible this is data from somewhere? Once I worked at a radio station & the chief engineer, no doubt competent in the early 20th century, laid a data line next to a mic-level line. You can guess who won that one.


Do not EVER turn on a tube amp without a load. Misery is guaranteed.

Depends on the amp.

A stable amp can be on but not driven without a load. 

An unstable amp may be a problem with or without a load.

the sound comes through the headphones.

Is the sound present on all inputs?

Does the level change with the volume control?

I too was stumped when there was noise in my tube preamp and in my tube phono. Turns out to be the Wi-Fi modem and (especially) repeater boxes were too close to my equipment. I could hear the noise abate as I moved them 12 -15 ft away. It falls off rapidly in an electromagnetic inverse squared fashion ....but if even turning off your internet equipment doesn't have an effect, it could be your neighbor's.



yes, all volumes levels and on all channels. Covering the unit with a faraday blanket does attenuate the sound.

Alright, the faraday blanket lends support to the "external radiation"/Wi-Fi theory. 

As a (possibly amusing/enlightening) side story, I had tried substituting other equipment as part of my logical deduction, detective methodology and found that a solid-state version didn't suffer the same noise (both pre and phono) and so, the units were obviously the problem (I thought/but really, just better shielded). My technician was not able to duplicate my problem but charged me anyway.  When I finally figured out what the problem was, I shared that with my technician, hoping and even suggesting that maybe he shouldn't have charged me. His wise response: "Turner, it's always what you don't know that costs you."

Think "out of the box/system" if all else fails. 

There's an Android app NetSpot that will show the level of WiFi RF in the area.

Sitting right next to home router is usually about -40dBm.

There are relatively inexpensive RF detectors available. The Best RF Detectors for Detecting EMF and RF Signals in 2022 – SPY

BUT, even if you find the source, getting something done about it may be difficult.

Since the sound is present on all inputs, you could pull the power tubes [labelling them first to restore to the same socket] to see if that makes a difference. Only power the amp for a couple of minutes as B+ will be high without the power tubes.






This may seem silly, but it can actually work quite well.

To test for RFI you can use an old transistor radio. Just turn it on and adjust the dial so it is in between stations. Turn up the volume and then use it like a geiger counter. When RFI is detected the radio will emit static.

Have you tried a Ferrite Ring Core RFI EMI Noise Suppressor Cable Clip, you can find them on Amazon and eBay? I had a serious issue with rfi in my system, I could hear the local am radio station broadcasts. I bought a package which included several different sizes that I was able to put on all cables attached to my amp and throughout my system. It offered me quite a bit of relief. I hope you figure out the problem, I know what it frustrating experience this can be.

When I had to live in an apartment I had an upstairs neighbor who played his stereo so loud that it disturbed my piece, quiet, privacy, and my right to choose for myself what music I wanted to hear. He bullied me with his trashy music when I asked him to stop. The landlord and the police refused to help me. My solution was to construct a microwave horn using microwave oven parts to disable his stereo. I wore a suit made of wire screen for my own safety. (Unprotected by laws and rules of common decency I did not care about the safety of my bully.) The microwaves got into the circuits of his amplifier and caused it to buzz loudly because the power supply to a microwave oven magnetron is a voltage doubling half-wave diode-capacitor system. 

Are you playing your music at a volume that violates the privacy of your neighbors? It is unlikely you have a neighbor who is fighting back if you are, but everybody who plays a stereo has a responsibility to respect the right of others to say no to music they do not want in their homes even if no law enforces it.