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

[TLS Guy]

Sorry, I am a little bit on edge now as it seems like I get no sound from the Classe after what happened.

I tried hooking up the two front speakers with the other RCA-XLR cable that I had not done anything with and there is now no sound coming out from the speakers (except for the hum). I also tried hooking up one of the RCA-RCA cables and did not get any sound on the speaker I tested with either. Really scared something went in the Classe

As for the above message, I am not sure if I understand this. I thought I did things correctly based on what I said in the former message (just cutting the Pin1 wire, taping it with electrical tape and leaving everything else as is for the cable)?

It looks as if you may have had only the live connected, and sent a big hum through. Does it hum with nothing connected to the amp. If it does, then something is amiss. If it is silent, see if you can get sound from a battery operated device, like a phone with a headphone jack. Any device with an audio output that runs from a battery will do the trick. It is not going to be easy to troubleshoot this from long range.

 

[TLS Guy]

Sorry, I am an idiot. I somehow had managed to connect it to the bloody Zone 2 connections next to the Pre-out for FR and FL. Been a long day… (life as a dad with two small kids and trying to solve these kind of issues after they have gone to bed is not always easy )

So look away from the first part of my previous message.

However still uncertain as to what I did incorrectly with the RCA-XLR cable.

That is a relief.

A signal to pass needs at least two connections. The signal out of your Denon receiver has a signal that goes +ve and -ve with reference to ground.

So the trick is to connect it to the balanced inputs of the Classe which are NOT connected to ground. So the live pin of the RCA needs to be connected to XLR pin 2 and the ground, which is the shield to pin 3 only and nothing to pin 1. That way there should not be a loop created via ground.

The whole cause of this is bad electrical codes in Norway. It is in no way acceptable for receptacles to not be polarized.

 

[Hobolicious]

It looks as if you may have had only the live connected, and sent a big hum through. Does it hum with nothing connected to the amp. If it does, then something is amiss. If it is silent, see if you can get sound from a battery operated device, like a phone with a headphone jack. Any device with an audio output that runs from a battery will do the trick. It is not going to be easy to troubleshoot this from long range.

Here is how it looks after I did the adjustments (obviously I closed it up as it was previously before connecting anything to the power amp). Is this correct?

When you say «does it hum with nothing connected to the amp» what exactly do you mean? Do you mean to leave the modifised XLR connector in the power amp, but disconnect the RCA connector from the receiver?

Really sorry for not understanding all of your input. I appreciate all the help.

 

[TLS Guy]

Here is how it looks after I did the adjustments (obviously I closed it up as it was previously before connecting anything to the power amp). Is this correct?
View attachment 65065
When you say «does it hum with nothing connected to the amp» what exactly do you mean? Do you mean to leave the modifised XLR connector in the power amp, but disconnect the RCA connector from the receiver?

Really sorry for not understanding all of your input. I appreciate all the help.

I mean nothing connected to any inputs on the amp. That means nothing plugged into any inputs on the Classe. Your pictures are not clear to me.

Anyhow I told you above the correct wiring arrangement. Live XLR pin 2 and RCA shield pin 3. I don't know how else to explain this.

 

[Hobolicious]

I mean nothing connected to any inputs on the amp. That means nothing plugged into any inputs on the Classe. Your pictures are not clear to me.

Anyhow I told you above the correct wiring arrangement. Live XLR pin 2 and RCA shield pin 3. I don't know how else to explain this.

From my understanding then the wire should be correct. Trying to explain the picture in more detail below.

Red rings are Pin1 and the cut wire with electrical tape. Blue rings are the red and blue wires running through the cable soldered to Pin2 (this should be “Live”, right?). Green rings are Pin3 where I assume this would be the RCA shield (not sure how to verify this):

And if this seems correct and I still got that heavy sound (the one you believed to be a large hum), how would I then go about as my next step to resolve that before trying again with the modified cable?

 

[TLS Guy]

From my understanding then the wire should be correct. Trying to explain the picture in more detail below.

Red rings are Pin1 and the cut wire with electrical tape. Blue rings are the red and blue wires running through the cable soldered to Pin2 (this should be “Live”, right?). Green rings are Pin3 where I assume this would be the RCA shield (not sure how to verify this):

View attachment 65066
And if this seems correct and I still got that heavy sound (the one you believed to be a large hum), how would I then go about as my next step to resolve that before trying again with the modified cable?

I did not realize that the RCA cable had two wires and a shield. Which wire is connected to the pin of the RCA plug and which the shield. I am assuming red is the pin and black the shield. You need to confirm this with your multimeter. If that is correct you don't need to connect the shield to anything.

You need to confirm that the cable connected to pin 2 is from the RCA pin with your meter and the black is connected to the outer part of the RCA plug. So then it would be red pin 2, black pin 3 and pin 1 not connected.

 

[Hobolicious]

I did not realize that the RCA cable had two wires and a shield. Which wire is connected to the pin of the RCA plug and which the shield. I am assuming red is the pin and black the shield. You need to confirm this with your multimeter. If that is correct you don't need to connect the shield to anything.

You need to confirm that the cable connected to pin 2 is from the RCA pin with your meter and the black is connected to the outer part of the RCA plug. So then it would be red pin 2, black pin 3 and pin 1 not connected.

Don’t have a multimeter at hand, but could lend one or just purchase a cheap one seeing they are not overly expensive.

How would I go about to do the measuring? You did not mention the blue cable going to Pin2, is your assumption that this one should be cut as well (after verifying with a multimeter) and that this would solve the issue with the large sound/hum I experienced?

 

[TLS Guy]

Don’t have a multimeter at hand, but could lend one or just purchase a cheap one seeing they are not overly expensive.

How would I go about to do the measuring? You did not mention the blue cable going to Pin2, is your assumption that this one should be cut as well (after verifying with a multimeter) and that this would solve the issue with the large sound/hum I experienced?

If you are in this hobby a decent multimeter is part of the basics.

You mean your circles, not the wires correct? I am summing the red wire with the blue circle is the 'hot' wire from the pin, but you need to confirm that with the meter. You check for continuity on the ohm scale, and continuity would show zero ohms.

So I assume the green circle wire is connected to the collar of the RCA plug. Again you need to confirm this. So that would go to pin 3. If all that is correct then your problem should be solved.

 

[Hobolicious]

If you are in this hobby a decent multimeter is part of the basics.

You mean your circles, not the wires correct? I am summing the red wire with the blue circle is the 'hot' wire from the pin, but you need to confirm that with the meter. You check for continuity on the ohm scale, and continuity would show zero ohms.

So I assume the green circle wire is connected to the collar of the RCA plug. Again you need to confirm this. So that would go to pin 3. If all that is correct then your problem should be solved.

What I meant was that there are two wires going to Pin2, one red and one blue. Not able to take a new picture, but you can see it highlighted here from one of the former pictures:

View attachment 65072
And as for measurements with a multimeter. How would you plug the cable and to what to make the measurements? Would you for example plug it between the receiver and power amp, but disconnect speaker wire from the power amp (to not get that large hum when doing the testing/measurements)? What are you expecting to measure on each cable?

Edit: Thinking about it I guess you would not connect it between the units seeing the XLR connector would have to be exposed to do the measuring.

 

[Hobolicious]

Seems like the image might not be working so trying again:

 

[TLS Guy]

What I meant was that there are two wires going to Pin2, one red and one blue. Not able to take a new picture, but you can see it highlighted here from one of the former pictures:

View attachment 65072
And as for measurements with a multimeter. How would you plug the cable and to what to make the measurements? Would you for example plug it between the receiver and power amp, but disconnect speaker wire from the power amp (to not get that large hum when doing the testing/measurements)? What are you expecting to measure on each cable?

What cable did you buy? There should not be that many wires in it. There should be two wires and a screen in each cable. The pin of the RCA should be connected to pin 2, The other wire from the shield goes to the wire to pin 3. You do not connect the shield to pin1 but leave it unconnected.

You use the OHM scale of the multimeter to test which wire goes to each end of the cable. So you put one probe of the meter on the RCA pin, and then on each wire in turn on the other end and see which wire shows continuity by a 0 Ohm reading. This will confirm which wire is the pin and which the shield. This is called a continuity check.

 

[TLS Guy]

Seems like the image might not be working so trying again:

I have no idea what cable you have there. There are too many wires I as far as I can see. If you use the meter correctly then you can tell which wire runs from where to where.

 

[Hobolicious]

What cable did you buy? There should not be that many wires in it. There should be two wires and a screen in each cable. The pin of the RCA should be connected to pin 2, The other wire from the shield goes to the wire to pin 3. You do not connect the shield to pin1 but leave it unconnected.

You use the OHM scale of the multimeter to test which wire goes to each end of the cable. So you put one probe of the meter on the RCA pin, and then on each wire in turn on the other end and see which wire shows continuity by a 0 Ohm reading. This will confirm which wire is the pin and which the shield. This is called a continuity check.

These are the cables I got.

Same cable on Amazon.

 

[TLS Guy]

These are the cables I got.

Same cable on Amazon.

That is the wrong cable. That is a dual mono cable. What you need is two RCA to XLR cables, one for each channel. They need to be to the specification I described previously.

 

[Hobolicious]

That is the wrong cable. That is a dual mono cable. What you need is two RCA to XLR cables, one for each channel. They need to be to the specification I described previously.

I see. That is unfortunate. If I remember correctly the cable you linked earlier was a tad short, and couldn’t seem to find a longer version from the same brand. Being in Norway I also have to calculate in the import fees ordering from abroad (as well as the delivery time).

I must admit that I am slowly moving in the direction of thinking that maybe it would be better to move on the Classe Audio CA-5200 while it still holds value, as well as the Denon X3800H, moving over to a Denon X6800H when it become available (cost wise the Classe+X3800H should be somewhat similar in price to the X6800H I would assume). And then long term, if necessary, I could add a 3-channel amp for the front stage (however uncertain if it would be necessary with my Dali Epicon 6 and Dali Epicon Vokal, especially considering the sound levels I am able to play at with two kids in the house).

Moving on would not be because I think the current problem is unsolvable by any means.

 

[PENG]

Now if the the Denon and Classe have their chassis connected in any way, there is hum. This occurs with no other devices connected and driven from the mains AC.

This is NOT the case, he said the following, when I asked him to clarify:

2) When I said disconnected I meant that they only things still left in the receiver (Denon) were 3 RCA cables running between the receiver (Denon) and power amplifier (Classe), power cord from the receiver (Denon), 8 sets of speaker cables running from the receiver (Denon), power cord from power amplifier (Classe) and 3 sets of speaker cables running from the power amplifier (Classe). As I also stated, I removed the 3 RCA cables running between the two units (Denon and Classe) to see if this eliminated the sound issue, which it did.

The core of the puzzle is that it is acting like a ground loop, but where is the loop?

I will tell you where the loop is. It is at the bonding of neutrals and ground at his electrical panel.

May be, but ground loop itself does not create the kind of hum noise he's getting, it only make such noise when the ground loop current flows in the signal path, that should be obvious to all of us.

With the AC plugs being reversible there is a huge excess of neutral gouging. I have encountered similar situations in years gone by when neutrals were allowed to be daisy chained all over the place, and wall sockets were not polarized. I think most of these situations have been updated and remedied in the US.

The OP needs to confirm what kind of plug his Denon is using, may be they have a way to avoid it being inserted incorrectly. Also, it it was inserted in the reverse polarized way, then he would have more than just a ground loop hum issue with the Classe amp.

So, his ONLY solution is to cut that ground to pin 1 to the xlr body.

Agreed, I said that before too, if the interconnect as is did not eliminate or reduce the hum enough for him, then he could try cutting that connection. Assuming the XLR connector can be opened up easily, it would only take a side cutting and a plier to do the job, in seconds. It is worth a try, and there is no safety concerns, only a slight concern of damage to his audio devcies.

Now that has NOT increased the hazard in this case, because the Denon will be connected as intended and protected with so called double insulation. The Classe will be grounded as intended. However, he won't have his hum. The hazard of using the equipment has not changed as everything will be connected AS designed.

 

[PENG]

I don't have a multimeter available, but potentially my father-in-law might. They are powered from the same outlet.

As for the subwoofers, I did disconnect the RCA cables towards the receiver from both subs with the problematic sound still persisting. I did however forget to remove the power cords from the power circuit (the subs are connected to two different outlets than the one the receiver and power amp are connected to. However, all of the outlets are connected to the same dedicated power circuit for the HiFi setup).

All outlets are newly installed and are grounded.

Is your cable connector wired as shown in their website picture below?

If it is, then we are only suggesting you try cutting the connection between pin1 and the shield, or the connector's shell casing if that's how it was soldered to. then it is not the one we previously linked to you as examples.

edit: This cable will not work.

 

[PENG]

I see. That is unfortunate. If I remember correctly the cable you linked earlier was a tad short, and couldn’t seem to find a longer version from the same brand. Being in Norway I also have to calculate in the import fees ordering from abroad (as well as the delivery time).

I must admit that I am slowly moving in the direction of thinking that maybe it would be better to move on the Classe Audio CA-5200 while it still holds value, as well as the Denon X3800H, moving over to a Denon X6800H when it become available (cost wise the Classe+X3800H should be somewhat similar in price to the X6800H I would assume). And then long term, if necessary, I could add a 3-channel amp for the front stage (however uncertain if it would be necessary with my Dali Epicon 6 and Dali Epicon Vokal, especially considering the sound levels I am able to play at with two kids in the house).

Why would you need the X6800H? If it is only for the two extra amp, why not just get that cheap class D amp I linked. Many Denon users have done so and seem happy with them.

Fosi Audio V3 Amplifier Review | Audio Science Review (ASR) Forum

If for some reasons, you don't like it, it is easy to return such a small a light amp.

 

[PENG]

So if I understand you correctly you are saying to «tuck» the Pin 1 within the connector instead of cutting the Pin 1 wire (making it easily reversible without having to resolder)?

The picture he shows is nothing like what we have been discussing, that is RCA to XLR interconnect. I have no idea what he's suggesting, so before you get it clearly from him, just wait and continue on things that you are clear about.

 

[Hobolicious]

Is your cable connector wired as shown in their website picture below?

If it is, then we are only suggesting you try cutting the connection between pin1 and the shield, or the connector's shell casing if that's how it was soldered to.

The very slight concern I have, as I explained before is that if on the Denon side, someone the RCA's shield/shell of the connector is not connected to "ground", then you might get "pop" that might be strong enough to damage your speakers. That's why I did not recommend it in the first place, and that's why the better way to combat this issue to wire pin1 to the shell with that resistor and capacitor shown in the Hypex document I linked a couple times before. If you have cut that connection absolutely correctly, when you try again, be sure to be ready to turn power off quickly if you heard any unusual sound, better still, try with just one speaker connector, preferable a cheap speaker, just to make sure there is no pop. The chance of such mishap is slight, but you never know, we are not there to see anything you do.

View attachment 65074

Not sure if you saw my pictures above to TSL Guy, but I at least only cut the wire to Pin 1 (and put electrical tape over the now exposed wire). The rest I left as it was. However, TSL Guy said this was the incorrect RCA-XLR (that it was a “dual mono cable”). As per my pictures above there are two wires going to Pin2 (red and blue wires), and then one wire was going to Pin1 (which I cut) and one to Pin3.