Tube PHONO preamp interference - RFI, EMI, bad grounding?

Definitely WiFi or cell phone antenna too close to inputs. I've added a small RF filter to the front of my stages to combat this.

Thanks for letting me know what model.

Was wondering about  provisions for a MC cart.

Asking to see what else is inside the box that might be picking up the signal?

And the unit is solid state rectified, all three tubes are used in the signal path

Heres an obvious, and silly question, but are the tubes properly seated in the sockets? Could they have been jostled with all the moving about?

@filipm , making a phono pre-amp is not rocket science. Good low noise design, good quality transformers (if they are MC and use them), precision parts for the RIAA curve, and some other basic engineers concepts. When it comes to tubes as well, your cartridge likely has enough distortion that the distortion of the tubes almost does not matter.

In my experience, most of the "sound" from a phono preamp comes from the matching between the cartridge and the preamp, and not some inherent advantage or disadvantage of the preamp. If it does not at a minimum have several matching resistor choices for MC and MM, I would not want to use it. Even then, for an MC, a mix of capacitor and resistor matching will yield the flattest response. I am not saying that is your personal goal, just it can be.

Why this matters is don't get hung up on your particular preamp. I would be taking it to a friends house and verifying there is not noise in a completely different location so that you can sell it. Then I would buy a preamp with a good range of matching resistor selections so that you can tune the sound for your cartridge.

probably yes, but what could that be? :) This one cost me $1100, sounds awesome at this price. Maybe Audio Research PH5 could beat it. 

There are three  tubes but they are not left/right channels. All of them work for both channels equally. I have read something like that, the first one might be a rectifier. 

I'll order the tubes and maybe the tube shields as well.

@filipm you have 3 tubes? And the noise is in both channels? I’m assuming one of the 12ax7 tubes is a rectifier? I would just replace that one to start with. 

Going back to ss doesn’t sound very appealing :)
 

Well there may be other tube units that won’t have the same issue. Also, pretty sure you can get a good solid state phono amp that would equal or beat your EAR in performance and noise rejection. 

I was told to try the tubes first, simply because the tubes in the 834p are not exposed. They are covered by a thick piece of metal that should work as a Faraday cage. 

Do you have any tip for the cylidrical shields? I have only found something on AliExpress or Ebay, looks like it's the exact same thing. 

thanks

Learn something new every day! Thanks @esarhaddon 

It may NOT be HAM radio but HAMs have been using PACKET radio for many years. It was just one more place to look for a source of trouble.
Packet Radio : Software for packet radio use - The DXZone.com

I wouldn’t waste money on new tubes. However if the 834 does not already have tube shields I would look into purchasing some aftermarket cylindrical shields designed to block EMI and RFI. Place one over each tube. Well designed ones also improve cooling and dampen microphonics .

I meant if I lift the device, the signal gets stronger. If I put it on the floor, it gets weaker. Just like a radio with an antenna.

Yes, I have just tried it again - turned of the only wifi router I have, along with a cellphone. It’s very simple over here, I don’t have any tv, more computers etc.

The device works well anywhere else I have tried it so far, that’s why I’m not suspecting the tubes. But I’ll try that. I just didn’t want to buy three more 12AX7 tubes before I try all the other options.

The building has 5 floors, I’m on 4th. The ceilings are 10 feet and the walls fairly thick. It’s in a city center.

I have just moved the stage to the other side of the livingroom, it’s about the same.

The best results are when I leave it on the floor - unplugged. As soon as I plug in any source - a TT, powered DAC without a source or just the RCA cables, it gets stronger.

- I’ll try a different turntable, the ferrite rings and then the tubes.

Going back to ss doesn’t sound very appealing :)

// oh, and the model is 834p deluxe without the volume knob. 1996

@esarhaddon , that is not HAM or CB. You can tell it is packetized data and/or for packetized processing. The keeps are the demodulation of the envelope. I will see if I can extract the frequencies of the "beeps" as that may provide a better clue of the source. Some items have well defined packet frequencies.

@audphile1 , the change that is described by the op, appears to be a rapid change increase raising above the floor, then the change stops happening about 5 feet up. The floor is likely acting like a shield, but it could also be ground plane effects, or an inductive current loop.

@filipm Amazon has clamp on ferrite bead kits.
https://www.amazon.com/Tamicy-Pieces-Ferrite-Suppressor-Diameter/dp/B08BPHCXR3

Unfortunately it can be tough to get proper specifications of anything on Amazon. Different clamps work at different frequencies. Digikey will cost you more, but you know what you are getting. For $20 though, start with Amazon. Based on your comments about the output cables, put clamps on all wires input, output, and AC. Due to stray capacitance, every wire can act as an antenna.

@filipm , are you in a high-rise apartment building?  The reason I ask is they often host large cell tower arrays on the roof as well as antennas for other radio types.

@filipm it’s unclear to me what you tried with wifi? Did you physically unplug from the wall all your routers, access points, extenders, devices that receive and or broadcast wifi and Bluetooth? Turned off all mobile devices (including phones, smart watches, tablets, computers)? This will help identify the source inside your apartment. You said if you lift the unit up the noise reduces? This can mean your downstairs neighbors have some sort of a device that can produce this interference. There’s just too many things…smart switches, smart devices, wifi access points, etc

Also, how old are the tubes in the unit? It would be interesting to change the tubes to something like latest production JJs or Gold Lions. Since you didn’t experience this with your solid state phono stage, if you don’t find and can’t eliminate the culprit, one of the simple options will be to go back to a solid state phono stage.

For Noromance, I would agree with your idea. Just because I recently;y got a new TV (air) antenna that had a built-in filter for WiFi frequencies. IT cleared up a lot of degrading interference. I would also suggest that Philipm looks at his neighborhood to see if anyone has recently added an Illegal CB radio amp or even a HAM operator putting up something new. HAMS are almost ALWAYS agreeable to helping you find a resolution to any interference from their Radio station. EVEN if their equipment abides with the FCC laws. In days gone by the Phono cart itself was one of the biggest offenders acting like an antenna. I also liked the Ferrite rings idea. THat has stopped many offending signals. I have them everywhere and even MY OWN HAM equipment does not get in the way of quality sound from my stereo. If the tinfoil ides had some effect, THat is the first thing I would replace with High-grade shielded Cartridge wires. I really liked the answers here. Not so many people talking stupid or trash, but helpful responses. I will probably get blocked for saying something nice about the site.

If it is louder near the floor, could it be the source of interference is in your downstairs neighbor’s apartment? How many floors in your building? 

Another thought, it might be worth investing or borrowing test gear that would allow you to positively identify what type of interference it is. For instance, if @theaudioamp is correct about it being a demodulation, perhaps an oscilloscope trace could prove that. just a thought. 

have you tried eliminating the ground, period.

MP 200 is poly alloy cartridge and in theory is like a moving iron cartridge. I had a similar issue and eliminated the ground and the pulsations and noise went away. This was with a tube phono section from Audio Hungary. Went SS now with SPL.

Agree, that the DAC plugged into the Phono would appear to be like a TT at first glance, however, completely different grounding protocol, and completely different sensitivity to the outside world and interference. 
 

Which EAR-834P model is it?

- I'm not using any switching power supply anymore with the dac nor with the streamer. 

- The problem with the phono preamp was there since I bought it, about three months ago. I have tried unplugging everything, even a freezer.

- Plugging in the DAC didn't do anything which basically means if I use a different turntable, it's won't solve the issue. 

- Ferrite cores are on the list, I'll definitely try the 100K grid stopper.

- Yes, I'm using a streamer but it was unplugged of course. Both the DAC and the streamer are powered from Allo Shanti linear PS. 

- Switching the phones off didn't help.

One more important thing to mention is the interference can be also received by the line stage - ARC LS16. I noticed it when I was switching tubes. It only happened when I opened the top mesh though. I'll try again now before I move the preamps to the opposite side of the room. That would confirm the signal is being caught from the air, right? 

- I have tried to bring the phono preamp closer to the wifi router, It doesn't seem to have any effect. I'll try again and share the changes. 

The strength of the signal depends on the height level of the the preamp. The higher I hold it, the stronger it is. I doesn't change above 1,5m/5ft but it changes with every inch closer to the floor below 3ft. 

I think it's the input of the preamp that is sensitive. It's even more sensitive with RCA cables plugged in. It's interesting that even with the input exposed the signal changes when I squeeze the output cables together, still, it never goes off completely. That's basically all I'm sure of right now. 

Thanks for the help, I really appreciate it. 

I believe I have heard something similar to this before - twice - but both were some time ago - the first time it was definitely a router. Turned off the router, problem went away. Someone near you may have a powerful router. That would explain why you do not hear it when you take the preamp elsewhere. Try putting the EAR next to your own router and see if the sound gets worse.

The second time, if I recall correctly, I believe it was a combination of my iPhone 6 and a Grado Sonata 1 cartridge (an unshielded cart) going into a Croft Micro 25 (12AX7's) - but it was intermittent. I was trying to record and occasionally a similar noise would cut in intermittently. I put my phone in airplane mode and the problem went away. It may not manifest in another location with because your cell may be working on a different cell frequency elsewhere or your phones's GPS was turned off, or your bluetooth was not connected to anything..etc..; I do not seem to have the problem any longer with my latest iPhone.

Are you using a streamer? 

It's amplitude demodulation of the envelope of a high frequency signal either RF or power. The beeps are to be expected. Source to be determined.

That’s a challenge, for sure.

Never heard any “noise” like that coming from my phono stage, or any other component for that matter.

Sounds like a radio that is trying to pick up a signal, that won’t tune.

And the beeps are odd.

As others have said, sounds like WiFi/router signal.

And as you’ve taken it elsewhere, and it works perfectly, it’s likely not a defective  phono stage. Adding the TT increases the noise, which makes sense as the cartridge will also pu the interference. 
 

Have you tried plugging another source, other than a TT, into the phono stage? Like your DAC (powered up, but with no signal/source of course…)

Just curious if that removes it. 
 

Sorry for your headache, must feel like you’re  chasing a ghost…

The EAR-834P box is a pretty solid brick of metal, which should help to shield the tubes from the interference?

Something is the source of that noise, I know you prefer to shield the gear, but hunting down the source might be an easier task.

Interference is too rhythmic to be tubes or dimmer. Moving the pre is good idea. I have Trifield Meter for just this kind of event, you'd be surprised how much rfi given off by certain equipment, transformers pretty bad, you may find quiet zone by moving the pre. Many years ago I had fm station coming through system, moved some components, shazam. Shielding components may also help, xlr good.

Probably you're wrong on both counts, but we shall see, if the OP keeps us posted.

Does not matter if well respected. It does not work where others had no issue. It is broken (as I noted and needs to be fixed), or it has a design flaw.

Whoa!  It is way premature to ditch the preamp, which is a well respected product from an established company.  And this problem is not typical of the unit.

Noise sounds like communications and/or a processor ramping up/down to do something. Any chance you are using USB to connect to something connected to your stereo or sharing a power supply for anything related to the turntable?  Phone into a USB charger near the stereo?

If none of the above, then I would consider you phone pre broken and/or poorly designed. There are some ideas above to reduce RF noise. The MFR should be doing that, not you. If SS preamps don't do this and this one does, I would ditch it.

Its not the tubes,so many people point to tubes when theres noise. 99% sure its not the phono pre amp.

That's a lot of interference.  Likely Wi-Fi or cell tower. If it's not a sensitive tube issue, you could try adding a 100k grid stopper resistor on the input pin of the first tube. 

Has this problem recently manifested itself, or have you always had it with this setup?

Can be through the air, through the AC line, or through some component.  Do any of your components have a switching power supply? Is this phono stage electrically  isolated from the turntable motor?  TT motors put shmutz back on the AC line, and it's wise to isolate the TT from everything else.  Are you saying that the AC supply to your audio is isolated even from the other apartments in your building?

First of all, I live in an apartment. The building is pretty spaceous so I only have direct neighbors above and below me. The livingroom has a dedicated circuit (I can turn everything off on the main switch and leave the livingroom on).

I have tried the wifi of course. I only have one led light and it was one of the first things I tried. Nevertheless, it could be another banality..

I’m not sure how strong the wifi signal of my neighbors is, it’s just if I take the preamp and move it closer to my wifi router, it doesn’t get any worse. If I open the wifi menu on my cellphone the signal looks pretty strong tho. Four of them with a full signal.

Rather than looking for the source I’d try to make the phono section more resistant to the interference. Sounds like it’s high frequency, right? The bass driver is moving as well sometimes, like it was trying to push 20Hz.

Do you think there’s a chance it’s coming from the electrical circuit? I called an electrician and he will bring a dedicated 12V battery that can power the preamp. But does it even count when the other components are powered from the wall?

And yes of course, I have tried all the sockets in the room, even sockets from another circuit.

So far it looks like a matter of position of the preamp.

I brought 6 meters xlr cables so I’ll move the whole linestage on the other side of the room, leading the cables under the carpet to the power amp.

Just to try it.

If it helps, I was actually thinking of leaving it that way even tho the cables between the preamp and power amp are gonna be 6 meters. (Paul from PS audio is using long xlr cables in their n1 listening room as well ;)

One more thing: dimmers.  Are there any dimmers on the same circuit with your phono stage? And by burglar alarm, I meant the modern type that work through a wifi connection.

Have you tried different electrical outlets in your home? What else shares the circuit that serves your audio system? Any fluorescents or LED lights in the vicinity? Any burglar alarms?

Sounds like a router or wi-fi extender/repeater.  

I too would go with the elimination process described above.  It has to be something in the house (unless you live next to a broadcast transmitter or a ham radio enthusiast).  Good luck.

Have you tried ferrite beads or cores around the cabling?  These are used to suppress RFI and other noise carried on cables.  You can try some on the cable coming from the tonearm. 

Have you looked for a possible source of noise within the home?  I know someone who found the source by systematically turning everything off one at a time.  It turned out to be his daughters string of LED lights which are on a different floor and different branch of power.

In my case, it was the burglar alarm box. Had to move it to another room.