Any UK PowerPlant owners help with these ground loop issues?

With my new Power plant regenerator, and only the following equipment on I experience two different hum issues, one the usual low level hum and the other one is a fast rhythmic clicking sound.

  • Chord pre-amp in av bypass mode,
  • two chord monoblock amps
  • Arcam AV40 home cinema processor.
    Chord equipment in music mode, totally silent.
    As I’m in the UK mainly aimed at a UK audience but happy to listen to any expert advice to resolve these two issues.
    Note - both are quite low level in volume, when a movie is playing at a reasonable level the issues are ‘overpowered’, but I know they are there and distracting from the fidelity.

UPDATE : the hum and clicking noise are a constant volume and do not change with processor volume increase.

I assume you’ve done the basics of isolating power from audio cables, removing all connections and re-adding one at a time, adding one component to the PP at a time, etc.

Tell us what you’ve tried.

In the past, I experimented ground loops from the hdmi cable. Try disconnecting the hdmi from your av processor and see if it goes away. I had a nasty loop from my projector to my processor. Only remedy was to buy a isolator for the processor audio outputs.

I’ve got some nice suggestions here

Yes, tried removing all components, I’m down to the basic equipment, listed above.
Very hard to run cable management as I’ve a combined music and 7.2.4 home cinema system.
That’s a lot of cabling and all have to go behind the equipment.

Latest I’ve tried is plugging my network switch into the power plant as ethernet cables go to my PP and blu-ray player. I tried removing the lan cables individually and checking, ticking still there.
The only audio cables that could be causing an issue, I think, are my home cinema .1 cables as these run along the floor beside power cables. I tried some cable management on these, trying to separate them from the power cords, still no success.
All other interconnects are off the floor and run between equipment and Arcam processor.

I’ll try the hdmi cables, I’ve three in my system, one for both inputs on my projector and another for audio from blu-ray player to Arcam processor.

One other point of note, the Arcam processor is double insulated so only two prong in mains plug, live and neutral. With my last PP I ran an earth wire from a screw on the PP to a screw on the Arcam and that helped with ground loop hum.
I tried this again with the new PP but both hum and clicking remained so I removed the earth wire between PP and Arcam processor.

Thanks to jvvita for suggesting checking the hdmi cables.
The fast ticking sound was being caused by a Belkin Ultra high speed cable, which is certified up to 48 Gbps. I tried reversing the cable to see if it would make any difference but it didn’t.
I used this cable for the audio portion of my blu-ray player, (with a fiber optic cable for video).
The cable is actually very good for audio and I’ve used this cable for a good while on my last PP without any issues.
Not sure whether this particular cable has developed a fault or if this brand doesn’t work with my current PP?
There’s just a residual very low level hum left which will be very acceptable when playing content at any sort of volume.
Thanks to everyone who contributed in helping to solve the issue.

Update … not there yet.
I’ve tried three hdmi cables now and all exhibit the same issue, which is unlikely they would all have the same fault.
The cable is being used in a Panasonic UB9000 that was recently modded by a guy in Norway.
The upgrade changed the switched mode power supply to a linear power supply and upgrades to the hdmi audio board.
I’ve tried my Panasonic 820 in the system and it doesn’t have the issue so does seem to prove the 9000 is at issue.
Emailed the guy and got a vague response about digital noise and cables.
I’ve still more work to do to exactly pinpoint the problem.

I think the cable isn’t the one to blame, but rather the grounding scheme of the processor. I could only get rid of this by those isolators I mentioned. I did not want to try tying the signal ground of the processor to the safety ground of my preamp, because I really did not want to mess with the safety ground. One could to it by tying the outer rim of an unused rca jack of the processor to the earth ground of the preamp.

So I resorted to the isolators I mentioned.

Maybe someone more knowledgeable than me would chime in here. Good luck!

Thanks for the reply, I looked at this previously but didn’t understand exactly how it works?
Could you explain please, what cables are being used here?

A little update on my issue, I think I mentioned when no hdmi cables are present in my processor the ticking disappears.
I tried a Panny 820 with the same hdmi cables briefly and that seemed to cure the issue.
I then re-jigged my system to allow the 820 to be stacked on top of my 9000 and tried the 820 last night.
The ticking was back, so more testing required.
Please explain the box mentioned above, I’m getting desperate.

I’ve had another look, I think I could use this, which uses balanced cables at both ends, i.e. input and output. (My AV40 processor uses balanced connectors.)
Behringer Ultra-DI DI100 DI Box: Musical Instruments

As I understand it, you go from your source to the processor via hdmi. From the processor to the pre-amp, I believe you go RCA.

The ground loop should be happening between source and processor (probably both double insulated), and going through the processor’s signal ground on to the preamp. You must then break the connection between the processor signal ground and the chord preamp.

You could try going XLR from the processor to the preamp. XLR normally are imune to these problems.

If you must go RCA, then one of these isolators should help (they were the ones that solved the problem for me, because I did not have the XLR option).

I would start with a cheap one just to try out the solution.

Hope I have been clear, and got your setup right.

Ah, … I raised an order for the XLR box I listed earlier and then quickly cancelled it again as I’m thinking my 9000 is hdmi, where do I use an XLR with this?
Your last email now makes more sense.
Yes, my Chord pre-amp is in av-bypass mode so I presume the box would go between the Chord pre-amp and the Arcam processor then.
Looks like I’ll have to try re-ordering the XLR box again.
(I’d rather stay with the XLR’s than introduce RCA’s into my system.)

Upon thinking, your explanation makes sense, I only get the ticking sound with my front left and right speakers, the ones powered via my Chord pre-amp, the other speakers aren’t affected.

jvvita … couple of queries regarding the XLR box.
I’ve re-ordered one from Amazon, as XLR’s are in pairs, for left and right, do I need to order two, one for each channel?
Also if only one is used, is there an issue with the cable lengths now being unequal, the ‘unmodded’ line still at 1 metre, while the box XLR length would now be two metres?

One further clarification about my system.
I’m using the dual hdmi outputs from my 9000 blu-ray player with a fiber optic hdmi cable going to my projector so I presume because this is an optical connection there should be no ground loops between the projector and the processor.
The hdmi audio output from the 9000 goes to the processor, for sound obviously.

yes, i guess the projector would not be the source of the problem. It is a bit weird you are having this kind of problem with XLR. I would not concern myself very much with the length of the cable. As for needing two boxes, you are right. But, if it were me, I would wait for one of them to arrive and see if it solves the problem on the channel to which it is installed.

Last, the box go int between your AV processor and your chord preamp.

What is the model of your preamp?

Chord 5000 pre-amp.

I looked at some photos and I think there is a grounding post in you preamp, right next to the triggers. Maybe you could consult with chord if it would be safe to run a wire from the outer rim of one of your processor’s rca jacks to this grounding post. If you do,this, you would be tying the signal ground of the processor to your preamp ground, potentially eliminating the loop.

But please don’t do this without talking to chord first.

Best of luck.

I got a Behringer box and nearly blew up one of my amps.
Behringer Ultra-DI DI100 DI Box, see Amazon.
Put in a 9v battery and XLR cable from pre-amp into box and output xlr cable from box into processor.
Had my equipment on and engaged the In/Out button, got a loud bang and my power amp shut down.
Luckily it came back again.
Sent info off to my Norway guy who modded the 9000 and he didn’t recommend using the Behringer as it’s for musical instruments, not hifi.
I di think I may be able to remove the battery connect it all up again and use the grnd switch to ‘lift the ground’ but very wary after my earlier experience.
Went back to basics - I’ve only 2 hdmi cables going into the processor, one from my 9000 for audio in and a 2nd one running from processor to projector.
If both cables are out, the ticking stops, if either cable is plugged in the ticking starts.
I don’t think my pre-amp has a grounding post, it’s an early model and grounding posts were added later in the development of the pre-amp.
I’ll check and I’ll contact Chord regarding this, after the Easter Holidays.

A direct injection box is for connecting an electric instrument, such as an electric guitar or synthesizer, directly to a mixer. It creates a balanced signal from the instrument’s single-ended output and matches levels (makes the signal much louder). It is absolutely not for use in an audio system.

Also, avoid Behringer equipment. Always. Behringer makes as cheap as possible clones of legitimate pieces of kit. Their equipment sounds dreadful.

OK, thanks, the Behringer box will be returned, luckily I purchased from Amazon.

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It just ocurred to me. maybe the pin 1 (ground) of the XLR output of the ARCAM is lifted (since it is double insulated). you could try hooking a rca cable from any rca output of the processor to any rca input of the preamp. If the hdmi and rca share the same signal ground on the processor, it might solve the problem (without any danger of blowing anything up).

Other than that, I am out of ideas, unless you convert to rca out of the preamp, to XLR in to the preamp, with a conversion box.

Surely it should be the other way round, RCA from pre-amp output to Processor input?

jvvita … what do you think about this, to be placed between my Chord pre-amp and Arcam AV40 processor? Uses XLR connections, passive, so no power required.
Ebtech HE-2-XLR Hum Eliminator with XLR: Musical Instruments