Noise pickup with phono stage RCA cables

[antcollinet]

Ha. Good analogy. I always thought this too until my current situation.

How are you grounding the turntable to the phono preamp?

OK - seen that in the video. The wire is pretty long, can you shorten it. You also have a loop of it over the PSU wire to the turntable (which I assume comes from a wallwart) - try to separate those. In fact keep the RCA leads separate from the power also.

Use your multimeter to check the turntable wiring from the cartridge to the phono connectors. (Disconnect the cartridge first), Make sure all wires connect through OK.

What volume is your amp set to?

And I notice you are in a garage - what is the power connection looking like. What other gear is in the garage running (eg AC plant etc).


Oh, and which turntable, which amp, which cartridge?

 

[Thorin]

Does the noise change if you unhook the ground wire only?

Is there an internal preamp on the TT? If so set it to off.

The buzzing gets louder with ground detached. No preamp with this turntable.

 

[dualazmak]

I assume it may be out of your present "issue" (seems to be ground loop?), my post here on my project thread related to EMF interference noise to phono stage preamp would be also of your possible reference...

 

[Thorin]

What is that taped down wire underneath the platter exiting the back?

Try to plug the cord for the receiver and table into the same outlet or power strip or try another outlet.

It's an led light under the plate. Not currently plugged in. The receiver and TT are plugged into the same outlet.

 

[Thorin]

I assume it may be out of your present "issue" (seems to be ground loop?), my post here on my project thread related to EMF interference noise to phono stage preamp would be also of your possible reference...

Does the pulsing nature of the buzzing make you think it could be something other than ground loop? I couldn't find any other example that sounded like this.
Thanks for the link to your project. I'll have to digest that later today. Looks very involved.

 

[dualazmak]

Does the pulsing nature of the buzzing make you think it could be something other than ground loop? I couldn't find any other example that sounded like this.

In my case, the noise was absolutely not by ground loop but definitely by EMF interference(s) possibly from one of the integrated amplifiers. You can find many such cases and counter measures by googling with key words "phono stage EMF noise".

Generally speaking, phono preamplifiers are very high gain amp especially in case with MC cartridges (x1000 voltage amplification needed); high-end extremely expensive phono preamps, therefore, are usually built "much heavy duty way" so that avoiding/minimizing intrusion(s) of outer (and of course inner) EMF interferences.

In case of rather affordable phono amps (like my AUDIO-TECHNICA AT-PEQ30), the EMF interference noises may be (can be) much reduced by just changing the physical position/layout moving far away from other audio (electronics) gears, and/or installing EMF shielding covers (like I did with thin copper plates); at least in my case, I did the both for successful results of 4 dB to 8 dB reduction of the EMF noises.

I just do not like to see the DSP's gain bars would be dancing around -40 dB zone due to the EMF noises to phono preamp (even almost inaudible though), and I could successfully reduced them below -48 dB (ref. here).

 

[dualazmak]

Thanks for the link to your project. I'll have to digest that later today. Looks very involved.

Thank you for your kind attention on my DSP-based multichannel multi-SP-driver multi-amplifier fully active audio project.

You would please find here the latest system setup as of August 3 2023.
Also Please find here (on the project thread) and here (remote independent thread post) the Hyperlink Index of my project thread and some of my related posts in remote threads.

 

[Thorin]

Dirty AC is the audiophile equivalent of blaming the dog.

I think my dog's been bad. Please take a look at this video and tell me what you think.

https://wistia.com/medias/bv2t8odnn2

 

[MAB]

I think my dog's been bad. Please take a look at this video and tell me what you think.

https://wistia.com/medias/bv2t8odnn2

Wow.
Can you try turning off your fluorescent and LED lights? Kind of reproduce what you did earlier, but this time going full-dark.
I am grasping at straws.

 

[Thorin]

I will tonight, but I've already done the sound test with the entire circuit panel shut off (except one) I'll run over and check the neighbor's power too. Now I think this problem may be posted in the wrong forum.

 

[raindance]

I will tonight, but I've already done the sound test with the entire circuit panel shut off (except one) I'll run over and check the neighbor's power too. Now I think this problem may be posted in the wrong forum.

Have you tried any kind of filter or isolation transformer/filter combo? Make sure, if you use a filter, that the device is actually a power filter and not just a surge protector. It sounds a bit like an issue I had in a performance space with a lighting control unit (it was interfering with microphone inputs on a mixer). You might be in the 0.001% of people who actually have a real interference issue .

 

[Thorin]

Have you tried any kind of filter or isolation transformer/filter combo?

Not yet, but I would appreciate suggestions if anyone has them. I'll try to solve the source of this issue, but I suspect it's outside my house. Having been frustrated with this going on a year now, I think I'll invest in something anyway. I'd buy it today if I had a clue what to get.

 

[raindance]

Perhaps this type of product from Tripp Lite:

IS1000

There are many choices, but I suspect that isolation AND filtering is the best approach. It is hard to say what will work though because a lot of the filtering schemes manufacturers use tend to aim at really high frequency noise rather than noise close to the mains frequency. Without analyzing your mains to see what is coming in and/or seeing how clean your house ground is (maybe it is the source of the noise), this is the best I can suggest.

 

[MAB]

Perhaps this type of product from Tripp Lite:

IS1000

There are many choices, but I suspect that isolation AND filtering is the best approach. It is hard to say what will work though because a lot of the filtering schemes manufacturers use tend to aim at really high frequency noise rather than noise close to the mains frequency. Without analyzing your mains to see what is coming in and/or seeing how clean your house ground is (maybe it is the source of the noise), this is the best I can suggest.

@Thorin could use REW and if he has a sound card with analog input, with the RTA.
REW is free. I forget to use it all the time in solving life's problems. And now am curious to measure my mains.

 

[Philbo King]

If there are ground binding posts or lugs on both the turntable and the phono amp / receiver try hooking a piece of wire between them. It has worked for me in the past.

 

[MAB]

If there are ground binding posts or lugs on both the turntable and the phono amp / receiver try hooking a piece of wire between them. It has worked for me in the past.

OP tried all that!
It seems he has a power plant just down the street that is in core meltdown, or military is doing particle beam experiments or charging up a railgun on his grid... (see post 30)

 

[Thorin]

Perhaps this type of product from Tripp Lite:

IS1000

I'm running a 200wpc Cambridge 851w on my primary system. How big should the isolation transformer be? 1000w might be overkill?

 

[Thorin]

If it was me, I would be getting the utility company involved. See if they have any answers.

Short term will be an isolation transformer. I wasn't sure if I need one with a battery, or as I said above what size it needs to be to be adequate for my system.

I'll check the neighbor's power first tonight, and if we all have it, ComEd will be my next call. The plot is very thick right now.

 

[raindance]

I'm running a 200wpc Cambridge 851w on my primary system. How big should the isolation transformer be? 1000w might be overkill?

I don't know, it depends in inrush, so I'd oversize it to handle all the audio gear at once plus overhead. It's cheap enough...

 

[Thorin]

Well everyone, it was my neighbor's 200 mile electric cow fence. Unplugged it and no more transients. Got some ideas from the electrical guys on a DIY forum.
We still have to fix his grounding issue, but I can finally see the light.
Thanks to all of you for your ideas and support. This was a tough one