Denon X3800H / Classe Audio CA-5200 - Ground Loop through RCA-cables?

[TLS Guy]

So the cables arrived today. I have not had the time to do a lot of testing, but initial testing does not seem to give the desired results. My small tests have been as followed:

1) I first tried to just swap the old RCA-XLR cables with the ones TSL Guy had produced, leaving everything wired as before outside of this change (so between the two units that means there are 3 x RCA-XLR cables, 1 x minijack for trigger and a speaker wire running between the chassis of the two units). This seems to produce the same outcome as the old RCA-RCA cables had (the ground loop, however potentially a little more subtle, though it is a long time since I had the RCA-RCA cables connected so can't fully remember the exact sound profile and sound level the ground loop was producing). The "popping"/"clicking" noise that the old RCA-XLR cables were producing is however gone. Further, it is acting very similar to the RCA-RCA situation in the way that at times the ground loop seems to suddenly go away (almost dead quiet), and then it just reintroduces itself. I have no idea how this is happening, but assume it has something to do with the speaker wire running between the two chassis.

2) I then tried to remove both the speaker wire going between the two chassis, as well as the trigger cable, but this just made the ground loop even more noticeable (meaning the sound level of the ground loop is higher).

3) I also tried connecting the speaker wire between the two chassis, leaving the trigger cable unconnected, but this seemed to give the same effect as 1).

This is so far a sad outcome, but at least it was worth the shot, and I would like to thank TLS Guy for producing the cables and shipping them my way.

Obviously, if you have any recommendations for what I should be trying before reverting to the old RCA-XLR cables please let me know.

Those cables should work.

I would get a multimeter and make sure that both units have their neutrals connected to the neutral in the outlet and the live wires connected to the live.

What I would do if this persists is to bond the two units together with a stout cable and make sure it always stays connected. Then replace one of the AC plugs with one that does not have a grounding pin to one of the units. If you do this it will be safe. Obviously there is a grounding problem with one of those units and I suspect the Classe, but it could be the receiver.

Lastly are you certain that nothing else with a grounding pin on the unit is connected to the system?

You must have only one grounding point!

 

[nicoleise]

@TLS Guy - Super cool of you to make and send those cables.

@Hobolicious - Which type of earthing system is used in your house (TT, TN, IT)? And can you confirm whether your amp must be grounded or if grounding perhaps is optional? It should state so in the user manual and probably on the back side of the device.


I don't think the mains plug polarity is the issue. The outlet/plug is not a Norwegian design/exclusive but is used in the vast majority of the EU.

There's no visible indication on neither outlet or plug, so it's not so much that the connection can be reversed, but more so that the connection cannot reliably be connected "straight" or even the same when reconnecting after having unplugged a plug.

This outlet and plug standard is the required in the EU, which essentially means that if a manufacturer would like to sell a product in the EU, the product must use this plug and be designed for these conditions. The manufacturer must declare that they conform to these rules before they can legally bring their product into trade in the EU.

So I would expect manufacturers to design accordingly and have never heard of this being an issue here. Denmark has a different national plug type which cannot be reversed, and we're transitioning to the common Schuko-type. So a lot of devices in Denmark are having their plugs changed to plugs that allow reverse polarity, yet no issues are reported.


Something that is pretty specific to Norway though, is a relatively widespread use of isolated earthing (IT earth systems). So if, for example, the power amp actually contains a ground fault, this will not cause any protective gear to trip, so long as it is the only ground fault in the house.

 

[PENG]

So the cables arrived today. I have not had the time to do a lot of testing, but initial testing does not seem to give the desired results. My small tests have been as followed:

1) I first tried to just swap the old RCA-XLR cables with the ones TSL Guy had produced, leaving everything wired as before outside of this change (so between the two units that means there are 3 x RCA-XLR cables, 1 x minijack for trigger and a speaker wire running between the chassis of the two units). This seems to produce the same outcome as the old RCA-RCA cables had (the ground loop, however potentially a little more subtle, though it is a long time since I had the RCA-RCA cables connected so can't fully remember the exact sound profile and sound level the ground loop was producing). The "popping"/"clicking" noise that the old RCA-XLR cables were producing is however gone. Further, it is acting very similar to the RCA-RCA situation in the way that at times the ground loop seems to suddenly go away (almost dead quiet), and then it just reintroduces itself. I have no idea how this is happening, but assume it has something to do with the speaker wire running between the two chassis.

2) I then tried to remove both the speaker wire going between the two chassis, as well as the trigger cable, but this just made the ground loop even more noticeable (meaning the sound level of the ground loop is higher).

3) I also tried connecting the speaker wire between the two chassis, leaving the trigger cable unconnected, but this seemed to give the same effect as 1).

This is so far a sad outcome, but at least it was worth the shot, and I would like to thank TLS Guy for producing the cables and shipping them my way.

Obviously, if you have any recommendations for what I should be trying before reverting to the old RCA-XLR cables please let me know.

One thing you can try easily, is to short out that parallel cap and resistor and try again. I think it is possible that something could have happened during soldering, it is a very tiny cap so it wasn't hard to cause damage to it.

You can try one cable at a time too, just to see if they both give you the same kind of hum.

After that, if it still doesn't solve the problem, then unless we are there to help you troubleshoot, it may be very difficult to narrow things down.

Also, there is still the <$100 Fosi V3 power amp that you can use to power the surround of height speakers. I know you may never believe it, but in a blind listening test, you will not be able to tell the difference between this cheap class D chip amp and your Classe amp. I have amps comparable to your Classe amp too and I am very familiar of the so call "sound" of expensive amps, including those much more expensive to your Classe. Those amps are well made, but they don't sound different than much cheaper amps that are designed to be transparent, when use well within their output limits.

 

[TLS Guy]

@TLS Guy - Super cool of you to make and send those cables.

@Hobolicious - Which type of earthing system is used in your house (TT, TN, IT)? And can you confirm whether your amp must be grounded or if grounding perhaps is optional? It should state so in the user manual and probably on the back side of the device.


I don't think the mains plug polarity is the issue. The outlet/plug is not a Norwegian design/exclusive but is used in the vast majority of the EU.

There's no visible indication on neither outlet or plug, so it's not so much that the connection can be reversed, but more so that the connection cannot reliably be connected "straight" or even the same when reconnecting after having unplugged a plug.

This outlet and plug standard is the required in the EU, which essentially means that if a manufacturer would like to sell a product in the EU, the product must use this plug and be designed for these conditions. The manufacturer must declare that they conform to these rules before they can legally bring their product into trade in the EU.

So I would expect manufacturers to design accordingly and have never heard of this being an issue here. Denmark has a different national plug type which cannot be reversed, and we're transitioning to the common Schuko-type. So a lot of devices in Denmark are having their plugs changed to plugs that allow reverse polarity, yet no issues are reported.


Something that is pretty specific to Norway though, is a relatively widespread use of isolated earthing (IT earth systems). So if, for example, the power amp actually contains a ground fault, this will not cause any protective gear to trip, so long as it is the only ground fault in the house.

That whole system sounds to me atrocious. If you are going to have reversible plugs, then there needs to be NO neutral with the energized pins in opposite polarity.
This thread is showing the issues that can happen.

The OP is going to have to go to one ground and break the others. Just more evidence that the EU is a disaster, and needed to break up years ago. If it is an EU reg, then it is likely daft. The farmers are in revolt and laying siege and well they should be.

 

[TLS Guy]

One thing you can try easily, is to short out that parallel cap and resistor and try again. I think it is possible that something could have happened during soldering, it is a very tiny cap so it wasn't hard to cause damage to it.

You can try one cable at a time too, just to see if they both give you the same kind of hum.

After that, if it still doesn't solve the problem, then unless we are there to help you troubleshoot, it may be very difficult to narrow things down.

Also, there is still the <$100 Fosi V3 power amp that you can use to power the surround of height speakers. I know you may never believe it, but in a blind listening test, you will not be able to tell the difference between this cheap class D chip amp and your Classe amp. I have amps comparable to your Classe amp too and I am very familiar of the so call "sound" of expensive amps, including those much more expensive to your Classe. Those amps are well made, but they don't sound different than much cheaper amps that are designed to be transparent, when use well within their output limits.

I don't think I damaged it. They were soldered fast and accurately. This cluster has it origins in the EU and their daft regs. The only solution is going to one ground and the others are going to have to be broken.

 

[nicoleise]

That whole system sounds to me atrocious. If you are going to have reversible plugs, then there needs to be NO neutral with the energized pins in opposite polarity.
This thread is showing the issues that can happen.

The OP is going to have to go to one ground and break the others. Just more evidence that the EU is a disaster, and needed to break up years ago. If it is an EU reg, then it is likely daft. The farmers are in revolt and laying siege and well they should be.

I don't think we really know yet, if this thread is an example of such an issue. I suspect other causes than polarity reversal between L and N.

And while I'm not exactly pro-EU, the rest honestly is just nonsense. German farmers are on strike because the German (national) government is reducing subsidiaries for farming.

What you're writing is similar to suggesting that if farmers in Iowa are on strike because Iowa introduced some state legislation they did not like, the US should disband.

 

[PENG]

I don't think I damaged it. They were soldered fast and accurately. This cluster has it origins in the EU and their daft regs. The only solution is going to one ground and the others are going to have to be broken.

I don't think you did either, but it is very easy to jumper it out just for a trial. Anyway, I think he should at least try to connect only one cable at a time.

 

[highfigh]

I would have at least thought they would have sent it to Paris or somewhere like that. Mind you France is a failed country right now, with Paris under siege by the farmers, who want to starve out the population of Paris like a medieval siege.

The dispute is over going green. The government has increased the cost of fuel to farmers, to burnish their green credentials. Like all governments, they are dumb as a rock. They are so stupid they do not realize that there are no electric tractors or other farm implements, and even if there were they would be so heavy they would be useless. So the farmers say they can't afford to farm and make a living at current prices. So they have blocked all roads going in and out of Paris with 800 or more tractors. They also have front end loaders and are piling up huge bales of hay across the roads stacked high. Nothing is being allowed in or out and especially no food items. Popcorn anyone?

So, you're blaming the farmers?

 

[TLS Guy]

So, you're blaming the farmers?

No, but there is just no end to the stupidity they can cook up in Brussels.

 

[TLS Guy]

I don't think you did either, but it is very easy to jumper it out just for a trial. Anyway, I think he should at least try to connect only one cable at a time.

View attachment 65693

It is, if you have the right tools. You need a micro Phillips screwdriver to open those switchcraft XLRs.

So the cables arrived today. I have not had the time to do a lot of testing, but initial testing does not seem to give the desired results. My small tests have been as followed:

1) I first tried to just swap the old RCA-XLR cables with the ones TSL Guy had produced, leaving everything wired as before outside of this change (so between the two units that means there are 3 x RCA-XLR cables, 1 x minijack for trigger and a speaker wire running between the chassis of the two units). This seems to produce the same outcome as the old RCA-RCA cables had (the ground loop, however potentially a little more subtle, though it is a long time since I had the RCA-RCA cables connected so can't fully remember the exact sound profile and sound level the ground loop was producing). The "popping"/"clicking" noise that the old RCA-XLR cables were producing is however gone. Further, it is acting very similar to the RCA-RCA situation in the way that at times the ground loop seems to suddenly go away (almost dead quiet), and then it just reintroduces itself. I have no idea how this is happening, but assume it has something to do with the speaker wire running between the two chassis.

2) I then tried to remove both the speaker wire going between the two chassis, as well as the trigger cable, but this just made the ground loop even more noticeable (meaning the sound level of the ground loop is higher).

3) I also tried connecting the speaker wire between the two chassis, leaving the trigger cable unconnected, but this seemed to give the same effect as 1).

This is so far a sad outcome, but at least it was worth the shot, and I would like to thank TLS Guy for producing the cables and shipping them my way.

Obviously, if you have any recommendations for what I should be trying before reverting to the old RCA-XLR cables please let me know.

I think the first thing is you need to assure us that there are no other grounds, like a connected sub, Ethernet or cable system connected to the rig.

We have to get back to ONLY one ground in the whole system. If there is only one ground and it still hums, then there is a problem other than a ground loop.

 

[ban25]

Also, there is still the <$100 Fosi V3 power amp that you can use to power the surround of height speakers. I know you may never believe it, but in a blind listening test, you will not be able to tell the difference between this cheap class D chip amp and your Classe amp. I have amps comparable to your Classe amp too and I am very familiar of the so call "sound" of expensive amps, including those much more expensive to your Classe. Those amps are well made, but they don't sound different than much cheaper amps that are designed to be transparent, when use well within their output limits.

+1 on the Fosi.

 

[highfigh]

It is, if you have the right tools. You need a micro Phillips screwdriver to open those switchcraft XLRs.


I think the first thing is you need to assure us that there are no other grounds, like a connected sub, Ethernet or cable system connected to the rig.

We have to get back to ONLY one ground in the whole system. If there is only one ground and it still hums, then there is a problem other than a ground loop.

Precision screwdrivers are cheap and available everywhere- Switchcraft changed to Phillips? All of the old ones I have and have seen had little set screws that used a straight tipped screwdriver.

I don't remember if the OP wrote that he had moved the sub close and to be on the same circuit as the rest of the system- if this hasn't happened, it should.

 

[TLS Guy]

Precision screwdrivers are cheap and available everywhere- Switchcraft changed to Phillips? All of the old ones I have and have seen had little set screws that used a straight tipped screwdriver.

I don't remember if the OP wrote that he had moved the sub close and to be on the same circuit as the rest of the system- if this hasn't happened, it should.

Those are Phillips.

 

[highfigh]

Those are Phillips.

Which 'those', the ones you bought? I didn't know they changed them because I haven't bought anything but the Neutrik type in many years.

 

[TLS Guy]

Which 'those', the ones you bought? I didn't know they changed them because I haven't bought anything but the Neutrik type in many years.

Yes, the new ones. You are correct, they used to be slotted.

 

[Hobolicious]

Hello again,

I thought I would just write a quick update. Unfortunately real life hit me in the face (and it feels like everywhere else too) so I have struggled to gather the energy to delve into the issue even further after the cables TLS Guy provided me with did not resolve the issues. Two small kids, full renovation of a house and a rather time consuming work does not always work well with trying to get the time to dive into your hobbies.

Because of all this I have started contemplating swapping the Classe with something else to see if this solves the issue at hand. Having said that I have not given up on solving the issue, I just need to be real with myself and how much time and energy I currently have to actually get to the bottom of it.

So not really any big update as of yet from my side, but thought I would still give you guys the time of the day seeing you have been very helpful up until now.

On another note, have anyone here had any experience with Parasound Halo A31? There is someone selling a used A31 quite close to me, and I was wondering if this potentially could remedy the issues I am facing, or if you believe I would likely face the same issues with such a unit? I guess it really depends on the location, but how much do these typically go for on the used market?

Might sound odd to some, but aesthetically the black finish on the A31 would fit my setup a lot better than the silver Classe is currently doing.

 

[PENG]

Hello again,

I thought I would just write a quick update. Unfortunately real life hit me in the face (and it feels like everywhere else too) so I have struggled to gather the energy to delve into the issue even further after the cables TLS Guy provided me with did not resolve the issues. Two small kids, full renovation of a house and a rather time consuming work does not always work well with trying to get the time to dive into your hobbies.

Because of all this I have started contemplating swapping the Classe with something else to see if this solves the issue at hand. Having said that I have not given up on solving the issue, I just need to be real with myself and how much time and energy I currently have to actually get to the bottom of it.

So not really any big update as of yet from my side, but thought I would still give you guys the time of the day seeing you have been very helpful up until now.

On another note, have anyone here had any experience with Parasound Halo A31? There is someone selling a used A31 quite close to me, and I was wondering if this potentially could remedy the issues I am facing, or if you believe I would likely face the same issues with such a unit? I guess it really depends on the location, but how much do these typically go for on the used market?

Might sound odd to some, but aesthetically the black finish on the A31 would fit my setup a lot better than the silver Classe is currently doing.

I can just tell you my experience with the A21, that has 2 channels instead of three otherwise identical to the A31, but obviously the A21 has a larger power supply on a per channel basis.

It is very well built, though but I could hear the 1200 VA toroidal transformer humming especially if I have any variable speed drive small appliances running such as a humidifier, so I would imagine things like light dimmers might have done the same too. If I run the humidifier at the maximum speed the hum would go much quieter, almost disappeared, but at low speed it was unbearable. Non of my other preamp, amps has audible transformer hum so that's a big negative for me.

In terms of sound quality, we compared it with a little $89 Fosi V3 amp and found no difference, same when compared with the Denon AVR-X3400H, a Hypex NC502MP, a Purifi amp, a Harman Kardon 3390 receiver, and my Bryston 4B SST, they all sound the same. Compared those using REW and Umik-1 mic, the mic heard the same too between 15-22,000 Hz. Anyone who claimed they heard differences between such amps that I owned, compared, I won't argue with them, but I know what facts are and understand how Placebo, expectation bias work. There is just no way any humans can hear things the mic and REW could hear period.

So, based on my own experience, You probably are anticipating that I would suggest you take the simple and stupid approach, that is, grab one of those $89 amp to drive the surround/height speakers, let the AVR drive the front LCR. Or for piece of mind, grab a 200/300 8/4 ohms amp from Audiohphonic, Nord kind of class D amps for the LCR and let the AVR power the remaining speakers, and then just enjoy the music. The A31 is huge and heavy, nicely build but afaic, such things are going to be for the collectors, not for practical use. If I am not downsizing, I would have kept my 4B SST and A21, but at this stage, it was an easy decision to replace them all with the mini amps.

Below is what my mic/REW heard between 3 "separate" amps, one being the Halo A21 and 1 Denon AVR, there can be no scientific (except if Placeo is science too) explanation if anyone could hear that Parasound Halo, class A (up to about 8 W) sound but there must be tons of posts about those different sound signature easily heard between those amps I compared.

I included some info on class D amps, if you are interested:
Class D power amplifiers | Audioholics Home Theater Forums

 

[ban25]

Aside all the points PENG mentioned, there's no guarantee there won't be a ground issue with that used Parasound amp, and you would be right back in the same boat. FWIW, I just ordered a Fosi ZA3 the other day for my own experimentation.

 

[Hobolicious]

I can just tell you my experience with the A21, that has 2 channels instead of three otherwise identical to the A31, but obviously the A21 has a larger power supply on a per channel basis.

It is very well built, though but I could hear the 1200 VA toroidal transformer humming especially if I have any variable speed drive small appliances running such as a humidifier, so I would imagine things like light dimmers might have done the same too. If I run the humidifier at the maximum speed the hum would go much quieter, almost disappeared, but at low speed it was unbearable. Non of my other preamp, amps has audible transformer hum so that's a big negative for me.

In terms of sound quality, we compared it with a little $89 Fosi V3 amp and found no difference, same when compared with the Denon AVR-X3400H, a Hypex NC502MP, a Purifi amp, a Harman Kardon 3390 receiver, and my Bryston 4B SST, they all sound the same. Compared those using REW and Umik-1 mic, the mic heard the same too between 15-22,000 Hz. Anyone who claimed they heard differences between such amps that I owned, compared, I won't argue with them, but I know what facts are and understand how Placebo, expectation bias work. There is just no way any humans can hear things the mic and REW could hear period.

So, based on my own experience, You probably are anticipating that I would suggest you take the simple and stupid approach, that is, grab one of those $89 amp to drive the surround/height speakers, let the AVR drive the front LCR. Or for piece of mind, grab a 200/300 8/4 ohms amp from Audiohphonic, Nord kind of class D amps for the LCR and let the AVR power the remaining speakers, and then just enjoy the music. The A31 is huge and heavy, nicely build but afaic, such things are going to be for the collectors, not for practical use. If I am not downsizing, I would have kept my 4B SST and A21, but at this stage, it was an easy decision to replace them all with the mini amps.

Below is what my mic/REW heard between 3 "separate" amps, one being the Halo A21 and 1 Denon AVR, there can be no scientific (except if Placeo is science too) explanation if anyone could hear that Parasound Halo, class A (up to about 8 W) sound but there must be tons of posts about those different sound signature easily heard between those amps I compared.

View attachment 66353

I included some info on class D amps, if you are interested:
Class D power amplifiers | Audioholics Home Theater Forums

View attachment 66352

Aside all the points PENG mentioned, there's no guarantee there won't be a ground issue with that used Parasound amp, and you would be right back in the same boat. FWIW, I just ordered a Fosi ZA3 the other day for my own experimentation.

Out of curiosity I struck a deal with the seller of the Parasound A31 that he would let me test it at my place to see if the ground loop persisted (before I would potentially buy it). Unfortunately I am experiencing the same issues with the Parasound as with the Classé (this was from very quick tests where I tested my RCA cables and RCA-XLR cables, as well as the RCA-XLR cables TLS Guy provided me with. The problem was present for all three cable types/brands).

What a big shame as I loved the aesthetics of the Parasound. It would have fit much better with my overall setup compared to the Classé.

 

[tillerman6]

After a long period of renovation I was finally able to prioritise the downstairs living room where my modest home cinema was to be set up. After all the work was performed and everything was hooked up I was ready to sit down and enjoy all the efforts. Unfortunately I stumbled across a very annoying sound from my front speakers and my centre speaker (which are connected to my power amplifier). From my research this seems to likely be a ground loop.

I will start of by listing my overall setup:

• Receiver: Denon X3800H
  • Speakers: Dali Rubicon LCR (SL, SBL, SBR, SR), Dali Phantom K-80 (TFL, TRL, TRR, TFR)
  • Subwoofers: 2 x B&W DB1 (Both connected with SVS SoundPath RCA cables)
  • Power amplifier: Classe Audio CA-5200 (Connected with 3 x SVS SoundPath RCA cables and 3.5mm minijack used for trigger)
    • Speakers: Dali Epicon 6 (FL & FR), Dali Epicon Vokal (C)
  • TV: LG 83’’ Oled C2 (HDMI)
  • Multimedia: Apple TV 4K (HDMI)
  • Gaming console: Playstation 5 (HDMI)
  • UHD-player: Panasonic UB9000 (HDMI)
  • Ethernet cable connected from a TP-Link TL-SG108

The reason why I believe this is likely a ground loop is based on the tests I have ran:

• Sound appears as soon as one (or more) RCA cables are connected between the receiver and power amp
• The sound does not seem to be affected by connecting or disconnecting different units from the receiver (TV, Apple TV etc.)
• I have tried hooking up a speaker cable between the chassis of the receiver and power amplifier (connected behind a screw on each of the units). This lowers the sound quite noticeably, but does not eliminate it
• Sound does not appear in the front and centre speakers when the receiver and power amp are not connected with each other

One very odd thing is that at random times the sound suddenly disappears (typically after quite a few hours having been powered on), but often reappears again shortly after. This is when I have had the speaker wire connected between the chassis of both units (I have not really ran the setup without the speaker wire between the units for long enough to see if the sound disappears at some point as the sound is too unbearable without the wire connected).

All units are connected to the same power outlet (which is dedicated for the setup and was recently installed by an electrician).

I am very much a novice both with HiFi setups and troubleshooting such issues, so hopefully your suggestions and experience can help me with this very frustrating issue.

One thing to try is having both amps and as many other sources as you can manage plugged into the same surge protector. It might make a difference. But that was a good move having chassis grounds between the RCVR and the other amp. That was what stopped my 60 cycle hum. I used the ground pin in the AM antenna socket for my ground on the RCVR end. Good luck!