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

[TLS Guy]

Hmm, I must have mist that in the previous posts. What would this involve? Would I need any specific tools to do this?

I can't tell from the pictures, but if the case can be opened it should be straightforward. If the XLR can not be opened without destroying it, then it won' work.

Usually if you have a problem like this, you make the cable yourself. If you can solder this is an easy job, and the way I would go.

 

[Hobolicious]

I can't tell from the pictures, but if the case can be opened it should be straightforward. If the XLR can not be opened without destroying it, then it won' work.

Usually if you have a problem like this, you make the cable yourself. If you can solder this is an easy job, and the way I would go.

Bugger, thanks anyways for the heads up. Wish I had gathered that before ordering the cables. Not much to do about it as they have already shipped, so worst case I will be 15-20 USD or so in the loss if I end up returning them (as I would have to cover the shipping each way).

 

[TLS Guy]

Bugger, thanks anyways for the heads up. Wish I had gathered that before ordering the cables. Not much to do about it as they have already shipped, so worst case I will be 15-20 USD or so in the loss if I end up returning them (as I would have to cover the shipping each way).

No, you can buy a couple of XLR male plugs, cut the XLRs off and solder them to the new plug the way you need it. Buy yourself a soldering iron nd a few soldering tools and learn it, if you have not done it yet. Every audio and AV enthusiast should be able to solder. That is just part of the basics.

 

[Hobolicious]

I can't tell from the pictures, but if the case can be opened it should be straightforward. If the XLR can not be opened without destroying it, then it won' work.

Usually if you have a problem like this, you make the cable yourself. If you can solder this is an easy job, and the way I would go.

Doing some quick research I believe the XLR connector will be quite similar to this one, so hopefully should be easy enough to disconnect Pin1. Fingers crossed.

 

[PENG]

Hmm, I must have mist that in the previous posts. What would this involve? Would I need any specific tools to do this?

It should be easy to do but I doubt you need to do it, probably shouldn't even do it. Hypex has not suggested it anyway as you can see in the diagrams I posted earlier. You can cut it, just that it, but at least try to leave it as it and see what happens first. Cutting it might increase the risk of other unwanted potential issues.

Here's another ASR post in which one guy wanted to make such as a cable, but you can see that he misread the Hypex, and the Monoprice cable's wiring diagram.

Making my own RCA -> XLR cables | Audio Science Review (ASR) Forum

 

[TLS Guy]

It should be easy to do but I doubt you need to do it, probably shouldn't even do it. Hypex has not suggested it anyway as you can see in the diagrams I posted earlier. You can cut it, just that it, but at least try to leave it as it and see what happens first. Cutting it might increase the risk of other unwanted potential issues.

Here's another ASR post in which one guy wanted to make such as a cable, but you can see that he misread the Hypex, and the Monoprice cable's wiring diagram.

Making my own RCA -> XLR cables | Audio Science Review (ASR) Forum

I think he should try that first, but it is unlikely to work. It seems the ground between the two units needs to be broken for some reason.

 

[PENG]

Hmm, I must have missed that in the previous posts. What would this involve? Would I need any specific tools to do this?

I agree with you, I suggested that he tried without cutting the connection first, because of what the Hypex engineers suggested:

Note that it says "the RC network can usually be shorted since consumer kit is always ground lifted. And even if it is not shorted, it (pin1), is connected to ground via the RC network, so they obviously have some concern. You and I both know how electricity work, so I suspect the concern with not having that connection at all, might be that in the rare instance when the shield/chassis ground connection is broken somehow, and that might result under certain conditions, loud pops that might damage something including speakers.

So I would still say leave the connection there, don't cut unless it still hum. I think we are in agreement on this strategy?


From the Hypex article I linked earlier (and I think we can assume that the Hypex team must have more practical experience than us):

It refers to the application, that has the following:
https://www.hypex.nl/media/c8/3d/26/1648383450/Application note Legacy pin 1 problems.pdf

 

[Hobolicious]

I think he should try that first, but it is unlikely to work. It seems the ground between the two units needs to be broken for some reason.

I agree with you, I suggested that he tried without cutting the connection first, because of what the Hypex engineers suggested:

Note that it says "the RC network can usually be shorted since consumer kit is always ground lifted. And even if it is not shorted, it (pin1), is connected to ground via the RC network, so they obviously have some concern. You and I both know how electricity work, so I suspect the concern with not having that connection at all, might be that in the rare instance when the shield/chassis ground connection is broken somehow, and that might result under certain conditions, loud pops that might damage something including speakers.

So I would still say leave the connection there, don't cut unless it still hum. I think we are in agreement on this strategy?


From the Hypex article I linked earlier (and I think we can assume that the Hypex team must have more practical experience than us):

I will just reply to both of you with an update at the same time. I received the RCA to XLR cables today and have now done some testing.

First of all I would just like to add that this testing was performed with the following connected:

• RCA to XLR cables between receiver (Denon) and power amp (Classe)
• Speaker wires to all speakers (three running from the power amp to FR, FL and C, and eight running from the receiver to the remaining speakers)
• Power plugs from both units (receiver and power amp)
• In one instance I also had a speaker wire running between the chassis of the two units (see below)

So to start off with the overall results of changing from RCA-RCA to RCA-XLR cables is that the sound level of the “hum” is a lot lower. I would go as far as saying that it is not something I notice in the listening position (but still noticeable when moving up close to the front and centre speakers). Still a speaker wire running between the two chassis did have an impact on the sound level (but with a lot less impact than previously as the sound level of the hum was already a lot lower with just changing to the RCA-XLR cables).

In the two recordings attached I have firstly tried to run only one RCA to XLR cable between the receiver and power amp for the Front Right speaker. Here I had no speaker wire running between the chassis of the two units. As you can hear there is still a hum present, but a lot quieter than previously. For the second recording I have all three RCA to XLR cables connected between the receiver and power amp, as well as a speaker wire running between the chassis of the two units. The recording is again of the Front Right speaker. What is very interesting is that as soon as a second (or third) RCA to XLR cable is connected between the two units a new type of sound occurs. It seems to be a “clicking”/“popping” noise. Luckily it does not seem to be loud enough for me to hear it in the listening position.

What do think is causing this new type of “clicking” noise?


When it comes to cutting the Pin 1 wire, I guess I could still test this seeing I have a “spare” connector (I have four RCA to XLR wires, and only need to use three of them)?

Attached you can find a couple of pictures of the connector and wires. Does it seem correct and can I just go ahead and remove the Pin 1 wire?

 

[ban25]

I will just reply to both of you with an update at the same time. I received the RCA to XLR cables today and have now done some testing.

First of all I would just like to add that this testing was performed with the following connected:

• RCA to XLR cables between receiver (Denon) and power amp (Classe)
• Speaker wires to all speakers (three running from the power amp to FR, FL and C, and eight running from the receiver to the remaining speakers)
• Power plugs from both units (receiver and power amp)
• In one instance I also had a speaker wire running between the chassis of the two units (see below)

So to start off with the overall results of changing from RCA-RCA to RCA-XLR cables is that the sound level of the “hum” is a lot lower. I would could as far as saying that it is not something I notice in the listening position (but still noticeable when moving up close to the front and centre speakers). Still a speaker wire running between the two chassis did have an impact of the sound level (but with a lot less impact as the sound level of the hum was already a lot lower with just changing to the RCA-XLR cables).

In the two recordings attached I have firstly tried to run only one RCA to XLR cable between the receiver and power amp for the Front Right speaker. Here I had no speaker wire running between the chassis of the two units. As you can hear there is still a hum present, but a lot quieter than previously. For the second recording I have all three RCA to XLR cables connected between the receiver and power amp, as well as a speaker wire running between the chassis of the two units. The recording is again of the Front Right speaker. What is very interesting is that as soon as a second (or third) RCA to XLR cable is connected between the two units a new type of sound occurs. It seems to be a “clicking”/“popping” noise. Luckily it does not seem to be loud enough for me to hear it in the listening position.

What do think is causing this new type of “clicking” noise?


When it comes to cutting the Pin 1 wire, I guess I could still test this seeing I have a “spare” connector (I have four RCA to XLR wires, and only need to use three of them)?

Attached you can find a couple of pictures of the connector and wires. Does it seem correct and can I just go ahead and remove the Pin 1 wire?

View attachment 65041View attachment 65042

Honestly, if the hum is quiet enough with XLR/RCA cables and the classis' connected together with speaker wire, you may be good to go. Any amp will have some amount of noise (hiss) coming out of the tweeter should you put your ear right up to it. So long as its not audible from the listening position, it should be fine.

 

[lovinthehd]

I take it the avr alone (speakers connected directly, no power amp) does not make the noise? I'm starting to think right now you just have a bit of amp hiss and tend to agree with ban25 otherwise.....

 

[Hobolicious]

I take it the avr alone (speakers connected directly, no power amp) does not make the noise? I'm starting to think right now you just have a bit of amp hiss and tend to agree with ban25 otherwise.....

Yes, you are correct. There does not seem to be any sounds (hiss or hum) coming from the Denon in isolation (meaning speakers connected directly to the Denon). I have previously tested the fronts and centre speaker connected to the Denon and did not experience these noises.

 

[davidscott]

Replacement for my REGA Carbon which is basically the same. I'm currently using an LP gear elliptical by AT for my REGA Planar 3 so this is a backup.

 

[Hobolicious]

View attachment 65043
Replacement for my REGA Carbon which is basically the same. I'm currently using an LP gear elliptical by AT for my REGA Planar 3 so this is a backup.

Not sure if I follow or if this was meant for a different thread?

 

[TLS Guy]

Yes, you are correct. There does not seem to be any sounds (hiss or hum) coming from the Denon in isolation (meaning speakers connected directly to the Denon). I have previously tested the fronts and centre speaker connected to the Denon and did not experience these noises.

Fitting that cap would be a good idea, and the safest solution. I bet that will cure it completely.

 

[Hobolicious]

Fitting that cap would be a good idea, and the safest solution. I bet that will cure it completely.

What exactly does this mean? Sorry if it is a dumb question (I am very much a novice when it comes to modification of cables).

 

[lovinthehd]

Yes, you are correct. There does not seem to be any sounds (hiss or hum) coming from the Denon in isolation (meaning speakers connected directly to the Denon). I have previously tested the fronts and centre speaker connected to the Denon and did not experience these noises.

How about using the avr without the amp? Does the amp change things much (aside from the annoying noise)?

 

[Hobolicious]

How about using the avr without the amp? Does the amp change things much (aside from the annoying noise)?

The receiver can only run 9 speakers on its own, so I need external amplification for at least two of my speakers (I guess I could run my center speaker from the avr as well, which is currently ran from the power amp alongside the front speakers).

 

[lovinthehd]

The receiver can only run 9 speakers on its own, so I need external amplification for at least two of my speakers (I guess I could run my center speaker from the avr as well, which is currently ran from the power amp alongside the front speakers).

That would get in the way Curious, is it as obnoxious a noise connecting the Classe to surrounds?

 

[TLS Guy]

What exactly does this mean? Sorry if it is a dumb question (I am very much a novice when it comes to modification of cables).
[/QUOTE

So you need a 100nf capacitor in parallel with a 100 ohm resistor in series with the shield and the grounding pin.

 

[Hobolicious]

Hmm, interesting. At first look, it feels a bit out of my comfort level. Am I correct in thinking I would need to open up the XLR connector, cut the Pin 1 wire and then solder the resistor and capacitor in parallel, and then resolder to Pin 1?

What is the reason this should be done compared to just detaching the Pin 1 wire? Do you now think detaching the Pin 1 wire is not a suitable solution anymore?