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

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 ;)

- 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 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

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.

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

@hagtech What RF filter are you using? There's many and don't know anything about these. 

Looking at the guide, it's definitely not hum or buzz. I know what to do to make them appear.

This is a very sharp beeping sound with a pulsing bass driver, I have posted the sample afterall. It's the same every time. 

What's interesting I can hear the same noise coming from my laptop charger sometimes. Of course it's not the source, one of the first things I unplugged.

@lewm I have taken the cover of the EAR off, with the tubes exposed, the noise doesn't get any stronger. Do you think the interference could get into the Faraday cage and be stopped by these aluminum hats? Maybe I could use an aluminum foil instead, just to see if it makes any difference. 

I'll try different tubes next week, even tho I have read they cannot be returned. Mullard CV4004 or Tung Sol gold pin.

@perkri yes, the tubes are sitting well in the sockets. I have taken them out and changed their positions too. 

@theaudioamp The building isn't the tallest in the area. I have checked the google map, recently updated by the way and there's nothing visible on our roof or on any roofs near by. 

An electrician is gonna stop by with a 12V battery that can power up the phono preamp. That should definitely eliminate a possibility of a noise coming from the electrical network. 

@audphile1

I get all kinds of responses that often oppose each other. If I followed everything, it would mean not to try anything at all. It might be ridiculous it’s the power line but I have to be sure.

I have read one thread here on Audiogon few weeks ago and someone stated he gave up after several months of investigation and got a solid state preamp.

It was here -

In this case the victim recognized the radio signal and it was picked up by the turntable. ;) the final solution was grounding. He even says "braided ground wires". I was told that it doesn’t make any difference if a ground wire is braided or not. Also that it doesn’t matter where you place the ground wire - because the components share the same ground.

@esarhaddon I have had this problem since I received the EAR phono preamp few months ago. I used to have a Bryston B60 integrated, at the time, I had unplugged everything, leaving all the sockets in the apartment empty. Even the fridge had to wait. I only plugged the Bryston and the EAR phono. It didn’t help.

I don’t think there’s any defective component nor is the phono preamp. It’s simply a signal from the outside. Could it be picked up by the power cables? Probably not, right, it would be the same as if it was coming from the power line.

I think if I placed my cables into a copper sleeve, grounded the sleeve and made another cage for the preamp, then it could work.Maybe the ferrite rings would do the same job as a copper sleeve.

So we powered the tube phono preamp with this battery. There was no change at all. Some added 50hz hum as we were messing around with the grounding. 

I can now say for sure it's coming from the air. 

@sbank Hey Spencer! :) When I read your posts I though to myself, well, I won't give up on my tube phono. I have just realized I haven't heard a vinyl for about two months and I don't think I can do two more. 

I am using really shitty power cables so my next thought is they might not be properly shielded. I scratched this option off when it was more and more obvious the rca cables and the input shows some changes. Plugging in any RCA cables even well shielded definitely extends the antenna effect.

I'll try to borrow better cables. Even though at my friend's place we used the cheapest crap we could find and it was absolutely quiet. 

I'm gonna ask my neighbor in the next building if I could test it out at his place. 

Then I'll buy the tubes.

About the tube shields - can they be substituted with several layers of aluminum foil? Just to see if there's any effect. It would take forever to obtain the tube shields from ebay.

@lewm I think what I have done with the baking pot proves that I'd have to use a sleeve for the cables as well. I have used 20 feet XLR cables to reach the other side of the room, closer to the router. Then I placed the router right next to the phono stage and put the phono preamp and the cables inside. Problem solved. Except it's not the most practical solution. :) The pot wasn't grounded but most of the cables must be inside. Once they pop out, they pick up the interference. 

There's actually a hint - even the output cables react to the interference. When I squeeze them, the noise changes. 

Let's see what an aluminum foil on the tubes does..

@lewm That’s for sure - I’d only wrap the tubes or the unit into the foil for about a minute. It takes a while, about ten minutes before the tubes are warmed up. Sonically even longer, the real listening with the EAR starts after half an hour and then it’s just getting better.

Yes, that’s an ARC LS16 mk1. It’s balanced, I’m using Nordost Red dawn XLR cables. There are different cables on the picture, balanced as well, about 20 feet long - I was trying to move it on the other side of the room to see if the noise changes.

EAR 834p isn’t balanced.

I have tested the EAR with several components, Bryston B60 for example - same results.

@dover Thanks for the tip but is the issue is shielding, I’d rather just add shielding to any cable than testing different brands. That could get quite expensive. If it proves to be the shielding then I’d gladly buy one of these cables.

A simple shielding test could be again the aluminum foil. I have tried this before and it kind of worked but the noise didn’t disappear completely. The shield should be grounded, right? Maybe a piece of wire between the shield and the ARC preamp?

It would be the best to share the recording of the noise on some radiophonics forum. The sound is very specific so eventually I could find the source.. or am I being naive? I have tried googling things like "wifi noise" etc.

If there’s about 4 to 6 wifi networks, they may be overlaping.

A sound sample at 1:00"

@plumptonvinyl The Chord Qutest is connected to a streamer right now. I’m using a Allo Shanti linear power supply with it and it sounds very good. My streamer is a Raspberry Pi plugged into the router with an ethernet cable. I haven’t got the soundcard for it yet but I will upgrade it soon. It’s also powered from the Allo Shanti. I have had this problem before I bought the streamer

@ejb14 

Ok, I'll get them as fast as possible. I actually got this recommendation a while ago but I have been trying so many things I have forgotten. Thank you. 

I have tried to find out how the wifi noise sounds like. Are you able to record it? Is it any similiar to what I have posted? (the noise sample on the top of this thread)

If the stoppers help, I'm thinking the RCA cables would have to be placed in a copper sleeve, maybe even two copper sleeves. I'd solder a grounding cable to the sleeves and ground it to either the phono preamp or to a screw on the ARC linestage. 

(I'm only suggesting this from my previous experiment with an aluminum foil - I had wrapped the input cables in several layers of the foil. The result wasn't perfect but it was ok just to see how the phono stage actually sounds in my setup.)

I'll also borrow some cheap integrated amp and a small speaker. There's a socket on the first floor of my apartment building so I'll test it on the hallway. If it won't pick up the noise then I'll do the same on the top floor. That should give me a hint where it's coming from. 

@theaudioamp thanks, this is nice. 50hz means a ground loop, right?

the system is overall quiet with the other inputs. there's only slight white noise on the DAC's input, audible only when I'm really close to a speaker and at high volume levels.

If it was in the building wiring the noise would be gone with that battery we have tried here. 

@lewm I'll have a different set of tubes next week. It's gonna take a while to get the shorting plugs.

I still think the EAR preamp is not defective simply because it works well anywhere else I have taken it. This must be an issue of the location. Soon I'll bring a simple integrated and plug it in in the hallway two floors lower. 

@theaudioamp That's possible but the noise if being picked up even when the turntable was unplugged from everything. The signal was just weaker. I can plug any RCA cable to the input of the phono stage to get back the strength of the signal, doesn't matter if the turntable is plugged in on the other side. That's the most confusing. 

I'll know more next week though. Different tubes, I'll do tests around the building with more practical intergrated amp (I'm using separates)  and I'll have the two closest neighbors' wifi switched off.

@atmasphere Thanks for the long answer. First of all, I totally agree it could be a matter of poor wiring (Even though I have tried the same TT and cables elsewhere and it was fine). But it can’t be the XLR part.

Is there a way to short the inputs without the input shorting plugs? (I have ordered them but it’s gonna take a while).

About the ARC - I have tried the same only with a Bryston B60 integrated, the noise has always been there.

The 20ft XLR cables were just an idea so I could move the phono section as far as possible from the speakers (or just to the other side of the room, possibly further from the neighbors wifi router). Otherwise I’m using 3ft Nordost Red dawn XLR between the ARC and the power amp.

@theaudioamp

It’s not only adding the RCA cable to the input but also moving the output cable around (without anything plugged into the EAR preamp)

If I have measured the right place, it’s a zero. I’m not sure what you mean by the signal ground of the phono input. If it’s the pin where the TT ground should be attached then it’s zero.

From the ground pin to the rest of the chassis the meter shows 33 ohms.

@atmasphere 

I bought the EAR before the ARC LS16 and it's been tested with other things, Bryston B60 was one of them. 

I mentioned it because it's a solid state integrated. When I plugged the EAR into the Bryston the noise was still being picked up. 

There's an interesting point about the ARC though. When I changed the tubes (it's mk1), uses 4 pieces of 6922, the noise was picked up by the ARC too. It was just very quiet and only when the cage was opened. That set of tubes was used, I think it was either JJ or the stock electro harmonix. I'll try if I can make the ARC to pick up the noise again. Anyways, I think it was only apparent for about a minute and then it disappeared. 

I'll have a different set of tubes for the EAR on Sunday. 

I guess there's nothing that could go wrong making the shorting plugs. I simply cut a piece of cheap RCA cable and connected the signal wire to the shielding wire. It still acts as a regular cable though, basically an antenna. 

I measured it with a multimeter - connecting the signal pin and the shield makes a beep. 

If there's something wrong in the EAR itself, how's that possible it's working everywhere else except my home? 😫

There's only one thing that made a difference so far - covering everything - the unit and the cables, mainly the cables - into a metal pot. Or making a thick aluminum sleeve for the input cables. 

Is it possible that there's an interference between the power cord and the output cables? But again. I tried the same cables at different places. Also, the EAR preamp has been powered with a battery. 

@ejb14 ok, signal and ground are twisted together. But the result is the same as if I plugged a regular RCA cable - a lot louder than emtpy inputs. 

@atmasphere when it's not running off the battery - when it's powered from the PS, it's the same except a 50Hz ground loop that is hard to get rid off when powered from the battery.

@ejb14 I can take detailed pictures of the input RCA and post it in here tomorrow. 

That makes the most sense so far - no matter what I plug into the inputs, it seems they are never grounded. Therefore the shielding isn't working, right? Maybe that's why the noise gets quieter when I touch the cables, even the output cables - I'm grounding it. 

I have tried connecting the chassis of the EAR to many things, I wasn't really succesful so far. 

Thanks, I think we're getting closer.

@ejb14 It's connected, both channels are. The grounding pin of the power input is connected, the case as well (but's it's painted so it can only be measured through the screws or one tiny spot where the paint has been scratched off)

How's that possible the shorting plugs aren't working? (This pictures shows the signal wire and the groung wire of that RCA plug before I twisted them together)

Is it possible that the tubes pick up the signal before it gets grounded? 

@audphile1 of course not. Not even plugged in. But I powered it on when I changed the tubes and left the cage opened - to see if they all light up. 

@lewm  @ejb14 I should have mentioned I live in Prague, Czech Republic. The voltage is 230V and the frequency is 50Hz. I posted it on a local forum but got quickly annoyed by the same jokes some people have been posting for the last two decades over and over.

I was in Berlin yesterday and took my EAR along. It worked perfectly fine even with the cheapest power cord and the interconnects I was using here. I didn't get the tubes yet but I returned with an ARC REF150 power amp. What a beauty.

Ejb, I'm now gonna read the article you have sent. Thanks. 

Exactly, if there was a lifted ground on the EAR, it would have been apparent at least at one of the locations I have been to. I wanna try to bring a small intergrated amp and plug it in on the hallway to eliminate the circuit in the apartment.

Is there any test I can do inside the apartment? I invited an electrician and he said the power line should be fine. 

@dover I already got an electrician over and it was the first thing he did. I demonstrated the problem with the phono preamp, he even brought a 12V battery and we had plugged the EAR into that. I have shared a picture in a one of the previous posts. 
Maybe I'll have to call him again, or I'll find someone else to be sure. I will consider getting the tester to do it myself. 
The building isn't that old, it's in the center but it's a functionalist building from the 50's. The power line could be 20-25 years old. I'll open up one of the sockets to take a look. The voltage is pretty stable too. The owner takes very good care of it.
I'll definitely call the electrician and make sure he checked it properly. But I think we even checked the grounding outside of the apartment. 
There's a different circuit in the kitchen, I tried to power up the EAR from there, no change nor difference in the noise level. I could run a power cable from a socket outside of the apartment.
I have finally bought proper power cables, they are on it's way. 
As soon as I sell the Classé power amp I'll get better interconnects too.
 

I have mentioned this issue in the conversation with the ARC staff as we were discussing the advantages of the ref150 over a ref110 (the use of KT150 tubes) and they basically said I should get the best interconnects I can afford and keep them short. 
 

And yes, I have tried lifting the ground in the EAR's power cord. 

@ghdprentice  the original idea was to find an ARC PH5, still affordable but all the ARC products are rare in Europe. So is BAT gear or Conrad Johnson. I have read how EAR compares to PH5 and I simply went this way.  
I'm a bit afraid I'd have the same issue with any ARC phono too. 
The REF150 is great, it gives a lot of room for improvements in the rest of the system. If I get an opportunity to get a good deal on an ARC phono I'll go for it.  
 

@ejb14 There is a transformer hum in the EAR. I thought that's normal. There's also some hum in the LS16. Nothing too loud but when you get head close to the device in absolute silence it's audible. 

The electrician didn't make it yet. But I got the shorting plugs. It's the same as the shorting plugs I have made. It makes no difference at all. - that's kind of a hint. 

Anyways, today's hifishark found an ARC PH5 stage in Netherlands. I'm thinking of picking it up. It will be interesting to see if it acts the same. I was also always curious how these two compare. If the problem remains, I'll sell one of them and keep looking for the solution or I'll just sell both and get a solid state phono stage.

I think you might be right about the lifted ground. I remember bringing home my first dedicated phono stage. There was some kind of hum too. I don't really know what I did but it disappeared after a while a remained pretty quiet. I also had a Primare R15 phono stage, it wasn't quiet either, there was this white noise at higher volume but neither of them picked the noise like the EAR.

That was the first thing I thought of, the transformer is making noise and the tubes are picking it up. But I would never guess the noise of the transformer is caused by a lifted ground. I'll take the EAR somewhere else again and see if the transformer sounds the same. (I didn't mention it before because it's very quiet and seems normal)

@ejb14 I have recorded the transformer hums.

I level of noise is not audible in the room of course but it's audible when you get closer to the device. The EAR is the loudest, the ALLO linear supply for my streamer and DAC is almost not audible at all. 

I placed my iphone microphone on the chassis when recording each of them.

I'd say it's normal but maybe I'm wrong. 

@ejb14 you have mentioned to check for DC presence on the line. Three days ago I have finally received an IEC19 connector for the ARC REF150 power cord and plugged it into the wall (instead of into a power conditioner that restricts the dynamics).

The power amp started to buzz after about 30 minutes of warm-up. I have also uploaded the buzz on the soundcloud page. (One recording is with the closed chassis, the other one is the opened chassis, moving the mic around). The buzz comes from the transformer, not the speakers, nor the tubes.

I called the ARC dealer in the Czech Republic and they said it could be presence of the DC. When they heard the recording, they said it would actually sound differently. What do you think it might be? Can the presence of DC actually damage components?

I have found a thread about the same thing with a REF150 on this forum, the OP had to replace the power transformer but also reffered to a bad tube on the input stage.

Maybe it has something to do with the EAR preamp problem, because both of these units were working fine when I was buying the power amp and listening both of them together in Berlin. 

(It has started with plugging the amp into the wall, worked fine with the power conditioner - technically. the sound is much better when plugged into the wall of course. From that moment it buzzez even when plugged back into the power conditioner)

My experience with tubes is starting to drive me crazy :)

I’ll have the results about the DC on Monday I hope.

If it’s the presence of DC, can any power plant fix this? Of course PS Audio will claim it can but our ARC dealer says it will restrict the dynamics no matter what power plant I choose.

@lewm I have done that. A quarter of a turn for each transformer to be fully tied up. I could probably do a little more but I'd have to push it hard. I'm already ok with spending something extra for a service, I just hope they won't suggest anything crazy like changing all the tubes and a transformer. They also said how important it is to have matched pairs and that you won't really find them on regular online tube stores. I have found a very similiar thread also with a REF150 (non SE version), contacted the OP and I think there will be more to it than the screws. I also talked to a guy who builds tube amps and he told me I should have replaced all the tubes right a way as a prevention. Well, I think it will get resolved sooner the EAR preamp issue anyways. 

@dpop Well, I used to have an Onkyo A7 integrated with a decent phono stage, Tesla ARS840 speakers and Tesla NC450 turntable (all for about $700). Good times, no problems (just horrible acoustics) and lots of listening time with friends. :) 

Now I have built some amazing acoustic panels and clouds, hanged curtains and I'm left with a streamer, chord qutest dac and a solid state power amp. Thanks god the LS16 is working!

I have tried: different power cords, RCA interconnects, powering the EAR from a battery, pairing it with different components, changing its physical location within the room, placing it into a baking pot, shorting plugs (I think that proves it's not the turntable or cartridge issue), running a ground wire into a socket ground pin, ground wire to a apartment heating unit., lifting the ground on the EAR's power cord, turning off everything in the apartment except the audio stage. I even had my neighbors wifi routers unplugged for half a day, different times - late night, early morning.. nothing changed.

what worked: taking the EAR somewhere else, friends' places etc. (sounds lovely), covering the unit along with all the interconnects into a baking pot placed on the floor (as pictured before), holding the output interconnects with both hands (grouding it).

what I would like to try: few floors lower - same building, plugging it in in a friend's aparment in the next building, a power plant, different set of 12ax7 tubes, some kind of a filter, tube shields.

My electrician says it could be some kind of a server station near by, or a bitcoin mine. He's coming back soon to measure the grounding properly along with the DC presence. 

But really, if it was coming from the AC line, the battery would have solved it. But if it's coming from the air, how come the shorting plugs didn't work? (The result with the battery was the same noise + strong ground loop. The shorting plugs just acted as antennas, just like a regular RCA cable. And yes, I have made them properly and tested them with a DMM.)

@ejb14 I am :)

I guess I’d have to get two of these Humdinger units - one for the power amp and one for the rest. Also, the question is how it restricts the dynamics of a power amp.

I have measured the impedance between the ground plug on the inlet and the grounding pin of the chassis (or any screw) - it’s 33.2 ohms.

REF150 - the impedance between the ground on the inlet and any screw on the chassis - 0.01 ohms (0.00-0.02)

Could there be a grounding issue on the AC line? It can, right? And it’s probably quite hard to solve I guess. There’s a dedicated line for the living (listening) room with about 5 sockets around the room. Maybe a lot easier than looking for a ground issue there could be to run another dedicated line that would power the audio stage only. (That would only exclude a router and few lights that don’t really affect anything - I have had them unplugged of course)

Just to be clear - the noise in the REF150 is happening inside the unit - on the transformer and does not affect the sound. Maybe the music gets lean and thin when the buzz gets stronger but that I’m not 100% sure of. Still, it could be another problem, not really related to the noise of the phono stage. The REF150 was a second hand purchase and even tho we listened to it for about an hour and it was fine, something could have gone wrong when plugged directly into the wall.

The noise of the phono stage comes out through the speakers.

Also - one thing I wanted to be sure of - with the use of shorting plugs I should eliminate any signal coming from the air, right? BUT when the chassis is not properly grounded the signal still comes through and gets picked up by the phono stage tubes, is that correct?

@dpop I have tried these chains:

TT - EAR - Bryston B60

TT - EAR - Classe CP60 + CA200

TT - EAR - ARC LS16 + CA200 or REF150

TT - CP60 + CA200 (as the CP60 has a solid state phono stage) 

(the LS16 doesn't have a phono stage even tho it says "phono" on one of the lines, only SP preamps have phono stages)

the noise gets picked up only by the EAR, solid stages (I had 3, they were ok)

At first I thought the EAR was the problem but the seller told me he never experiences anything like this. So I took the EAR to my friend's place. Horrible wiring, cheap components - absolutely quiet and great sounding. 

Right now I have covered the input cables (TT>EAR) with a metallic sheath, there's a little improvement but I can tell it gets picked up by anything, the input, output, the grounding cable, maybe the power cord too. Maybe it's really a grounding problem as I measured 33 ohms between the grounding pin on the chassis and the grounding pin of the inlet. but I had it opened several times, the groundind pins are well soldered, I even had few capacitors changed. 

@ejb14 

These had to be replaced. R16 died, the others were replaced along with it. 

It stopped working for a while as I was experimenting with it. 

I'm thinking of sending it to the factory, at least I will write them again with a suggestion.

@dpop I have also tried RCA only interconnects with two of these chains. For example Bryston B60 doesn't have XLR inputs. Now I'm only using XLR between a preamp and a power amp. 

33 ohms were measured on the EAR's phono ground pin or any screw (chassis) and the ground pin on the inlet. All the other solid state phono stages worked fine. Maybe except a Primare R15, there was a pretty loud surface noise, kind of like white noise. 

I always thought it was a subjective point of view, my girlfriend keeps telling me I only keep analyzing the system (of course when I'm not happy with the sound). Nevertheless I always had a feeling there's not enough juice in it, specially with the Bryston B60, it wasn't stable, sounded weak or lean sometimes. I was always surprised when I took the amp elsewhere. 

What else can we measure on the AC line when an electrician comes over? 

There's a simple voltmeter on the power conditioner I'm using for the sources. It shows some drops time to time, it's usually around 228-229V but it goes down to 225. If we find out the AC line is horribly dirty and unstable, is a power plant good idea? Something like PS Audio PP12 (I'm just a bit confused now, I have seen some measurement that suggest it's an overpriced piece of crap and I'm being told to stay away from power conditioning)

@ejb14 We'll see what we can find on the AC line but I wouldn't be surprised. I am already looking at some power plants. Not sure if PS Audio is the way to go, I have been told by ARC that they recommend plugging their power amps directly to the wall otherwise I'll end up with limited dynamics. Other people say their system sounds better with a PP without any restrictions in the dynamics. Haven't tried any filter, nothing. 

I'll check what the capacitors say, a friend of mine has replaced them for me. I still have a picture of the old ones. 

The step-up transformer - yes, the noise level is different. the opposite I'd expect actually. I have a MM cartridge and the noise is stronger when the EAR is set on MM. There should be higher gain with MC settings but the noise is less audible, significantly. But it's still there for sure - and it would also be audible during playback.

I have talked to a guy who builds tube amps, a local. He's willing to take a look at the REF150 and I will take the EAR along. If he won't find a problem, I'll sell the EAR. It's gonna be a bit weird if someone comes to listen to it though :) 

@dpop 

The 33 ohm resistance can be there to avoid a ground loop, as I was told by people who build tube gear. 

You're right, I won't linger on it. I'll let one more person to see the preamp and if he says it's fine, I'll sell it. If not, we'll try to repair it.

I found the answer from the EAR factory - 

It's difficult to say but I suspect a broken earth connection to the screening of the input cable or possibly a broken earth connection on the 834P itself.

This would account for the lower noise level when touching the cable where the user's hand would give some grounding effect. 

Does the noise go if all input cables are disconnected from the 834P ? 

Be careful with adding additional earths as this may create an earth loop and introduce hum noise. The other possibility is a poor earth on the 834P metal top cover. This should be grounded via the four fixing screws. if this is not grounded it will pick up all sorts of external noise.. 

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I'd like to try PH5 phono stage but it's a real hunt in Europe. All the ARC preamps are always gone really quickly. 

@atmasphere  yes, I was referring to the EAR.

I have measured the impedance between the ground of the RCA input/output and the chassis. You're right - it's 0.01 ohms.

Seems like there's a poor grounding on the inlet. I wrote to EAR if that's on purpose or not. 

Thanks! 

What can I do to find out what causes this 33 ohm resistance? 

@dpop I'm still here. Just working late last few days and haven't got the time to reply properly. 

I'm not sure if things are resolved but what @atmasphere mentioned sounds like the answer. I haven't got a reply from the EAR factory what are their thoughts on that 33 ohm resistance on the grounding. I'll have to find what causes that resistance and fix it. Or someone else will have to fix it for me. 

I'll have time to take more measurements tomorrow night. 

Thank you!

@atmasphere It is pretty simple - the resistance occurs here. It's either in the wire or in the joint. But the resistance between the grounding pin of the chassis (not the inlet) and the solder joint is 0.01. 

I'll try to resolder the chassis ground wire to the ground pin of the inlet. 

@ejb14 We have tried both MM and MC settings, worked just fine. There's nothing touching the board. 

@dpop That silver screw is holding a plate between the transformer side and the tube side. 

There's a 33ohm resistor on the grounding cable between the chassis and the inlet.

@lewm so removing that 33ohm resistor wouldn't be a good idea if I understand it correctly. 

The resistor is right behind the ground plug of the inlet so it's basically anywhere if I place one probe on that plug. 

@ejb14 they sell them here, about 20 cents a piece. they have two options, 33ohm 1W or 33ohm 3W. but nice guess - vishay dale :)

I have already taken pictures of the preamp. I think I'll sell it. I'm always reading how wonderful it sounds, how upgradable it is but I'll try to find an ARC PH5. 

@lewm Yes, I didn't realize the resistor might be there. I was told that sometimes it's intentional to avoid ground loops. But at the cost of poor grounding? 

I'll buy a new one but I'll also try to solder the ground wire without the resistor. 

@ejb14 communication with EAR isn't like ARC customer service (super fast), unfortunatelly. They responded only twice and it took them a week or two. 

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@dover I think If I wanted achieve the best shielding possible I'd have to leave the two green wires as they are but to cut out the 33ohm resistor. Then everything (the board, the chassis) would be grounded through the IEC with no resistance. I may be wrong, please take in account I'm a noob at this and I'm often missing what for others is common knowledge. So maybe if I cut out the resistor, it will lead to a ground loop.
I think if I unsoldered the green wires from the pin and soldered them together, I'd just ground the board while the cage would be left absolutely unshielded. 

@dover It’s the other way around on the EAR I guess.

Here is a picture of the ground binding post. The wire on the right is connected to the circuit board. The one on the left leads to the IEC through the 33 ohm resistor.

That means the chassis relies on the grounding pin and not so much on the ground to the IEC, correct? Nevertheless, I have tried grounding the chassis using this pin and separate wire leading to the socket ground pin, a heater, chassis of the ARC preamp.. none of these made a difference. Maybe I was just using a poor wire (the was almost no resistance on that wire).

I guess things could change if this 33 ohm resistor was moved to the wire on the right - between the grounding pin of the chassis and the circuit board ground. Then the ground of the RCA connectors would be closer to the ground of the inlet and not the circuit board.

@dover the chassis and the board are connected by those green wires. 

board > right green wire > binding post < left green wire - 33ohm resistor - ground pin of the IEC. (which means the left and right wire are meeting in the binding post)

also, there are screws holding the board but they are not touching the circuit of course. 

There is a possibility that the joint of the board ground (where the circuit board and the grounding wire meet) needs to be resoldered. 

If I desolder the 2 wires it only means the chassis would be completely lifted from the ground. The chassis and these wires wouldn't be even electrically connected. 

What's your suggestion?

Let's not forget the error may not be in the preamp. It's working fine anywhere else but my place. Maybe it just needs better grounding from the binding post. But where to attach it if not the socket ground pin? I have no idea. 

(It's possible the grounding problem leads further - maybe the sockets are poorly grounded. Maybe there's a problem in the main switch. We still haven't measured that, if it's even possible. I'm waiting for the electrician to show up.)

Would you suggest trying to move resistor between the audio and the ground plug? While chassis > IEC would be connected directly.

I’ll have to buy a new one. Will this work? - MBB02070C3329FCT00 (serial number of the resistor) - It was a Vishay dale, 33.2 ohm.

The resistor says "33R2F RN60P 9322J DALE"

I think the noise is air borne. Everything I have tried suggests it is, and yes, the chassis definitely acts as an antenna.

It simply cannot be in the AC because we have powered the EAR with a battery. The noise stayed the same.

Thank you

Or I could leave the resistor where it is and try to ground it through the ground plug on the chassis. What would be the most effective way to do it? Connecting a ground wire to a line stage chassis doesn’t work at all.

If the proper grounding won’t help I’ll sell the unit. It worked everywhere else. I’d be looking for an ARC PH5 which should be better anyways.

Hello again,

I have sold the EAR phono preamp few weeks ago. It was replaced with RCM sensor 2 phono stage (solid state).

It's a different story when it comes to the sound, there quite typical differences as in other tube vs. solid state comparisons. I'm very happy with the sound overall. 

Anyways, the phono works well when plugged into unbalanced mode.

I have just brought XLR cables to try the balanced mode and I get a ground loop.

The volume of the loop depends on the RCA cables used between TT and the phono stage. 

I have tried XLR cables with shortning plugs and the interesting thing is I get a loop only from the left channel. 

When I remove the plugs and leave the input without any connection, the loop is still there - not as loud though. It gets a little louder when I remove the TT ground cable. 

Any suggestion what to do? I'd like to use the balanced output of the phono, even with the loop I can tell it sounds better. 

The chain is TT - RCA / single ended, shielded with separate ground wire -> RCM phono -> XLR out -> preamp

Could the problem be in the TT grounding?

The whole system is plugged into one wall outlet. 

Power amp plugged directly into the wall and the rest is on a unfiltered power strip.

Ok, solved it by now. (The selector for balanced or unbalanced in the back of the RCM is for the input, not the output.)

Works fine with both RCA or XLR. Great phono stage.

The new owner seems to have no issues with the EAR 834p. The interference still remains a mystery :)

Thanks everyone for your help!