Fosi ZA3s Hum when connected to 12v remote cables. Help!

[2muchstuff]

Hi. I am having an issue with using the 12v turn on remote with my 2 Fosi Audio ZA3s. When I connect the cables, everything works ok. The amps turn on when the receiver does, but there is unfortunately a very noticeable mid pitched hum that come out of the speakers when there is no music on. Just a background hum that is very annoying. This is audible on both ZA3s. The cables I am using are

Amazon.com

I also tried a totally separate stereo cable and still it hums. Does anyone have any thoughts on how I can get rid of this noise? Wrap the cables in copper or electrical tape? Should I be using specialty cables?

My receiver is a Rotel 1056 with 2 separate 12v remote outputs. Each of them have exactly the same hum.

Thoughts?

Thanks so much.

2MuchStuff

 

[Guddu]

Hi. I am having an issue with using the 12v turn on remote with my 2 Fosi Audio ZA3s. When I connect the cables, everything works ok. The amps turn on when the receiver does, but there is unfortunately a very noticeable mid pitched hum that come out of the speakers when there is no music on. Just a background hum that is very annoying. This is audible on both ZA3s. The cables I am using are

Amazon.com

I also tried a totally separate stereo cable and still it hums. Does anyone have any thoughts on how I can get rid of this noise? Wrap the cables in copper or electrical tape? Should I be using specialty cables?

My receiver is a Rotel 1056 with 2 separate 12v remote outputs. Each of them have exactly the same hum.

Thoughts?

Thanks so much.

2MuchStuff

I have tested ZA3 trigged input with an AVR as well as DAC, and it has worked every time without any issues.
Is it possible for you to borrow another AVR/receiver/DAC from someone and then test, it might help you isolate where the issue is.

 

[raindance]

Does it work properly if you simply disconnect the negative lead for the 12 volt trigger? I suspect it is providing a second path to ground and causing a ground loop.

 

[2muchstuff]

Does it work properly if you simply disconnect the negative lead for the 12 volt trigger? I suspect it is providing a second path to ground and causing a ground loop.

Can you explain more of what you mean here? The cables I am using are mono. Is there something else you mean?

 

[raindance]

Another question: does either component have a ground lift switch? My idea of lifting the earth requires cable surgery.

 

[AnalogSteph]

A 12 V trigger input should be galvanically isolated from everything else. (I mean, what does it have to do - power a relay coil or light an LED in an optocoupler?) Otherwise the construction is just broken. Some reverse-engineering may be required to prove the issue, or just probing with a multimeter and some cables - it goes without saying that nothing on the trigger input should have contact with amplifier ground.

 

[2muchstuff]

I suspect it is just the rotel. Something is off there. I have a multimeter and cables, but I am no master in that field. What would you suggest?
Everything is being powered with a proper furman power conditioner. I dunno. It's strange. Could there be a cable (there is lots of them) that could be interfering? I am using the Rotel as a pre-amp to the Fosi's. Does it matter if the cables are stereo or mono? Could I wrap them in copper tape or is that just dumb cuz the tape needs grounding? Sorry folks, I am a newby here. It's not a big deal, I can just keep the fosi's on all the time, but it would be nice to use the remote. I got a request out to Fosi, too. Maybe they will have a thought. Thank you everyone for your time!

 

[2muchstuff]

Another question: does either component have a ground lift switch? My idea of lifting the earth requires cable surgery.

None of the components has a ground lift switch. But I do have one of these...I could put it in the signal chain. Use the balanced cables and put on the ground switch which it does have. But it is another piece of gear in play. Maybe I'll test it tomorrow, but it prolly won't impact anything. https://www.amazon.com/rolls-DB24-Stereo-Direct-Interface/dp/B001032GK8/

 

[2muchstuff]

I have tested ZA3 trigged input with an AVR as well as DAC, and it has worked every time without any issues.
Is it possible for you to borrow another AVR/receiver/DAC from someone and then test, it might help you isolate where the issue is.

I do have a simple NAD pre amp, but none of the stuff I have has remote turn ons. I am surprised the rotel, which is a proper piece of gear is creating this. I love troubleshooting, so I am open to whatever. It's such a silly no big deal problem, but we all geek on this shit so I figured I'd get the masters involved.

 

[raindance]

None of the components has a ground lift switch. But I do have one of these...I could put it in the signal chain. Use the balanced cables and put on the ground switch which it does have. But it is another piece of gear in play. Maybe I'll test it tomorrow, but it prolly won't impact anything. https://www.amazon.com/rolls-DB24-Stereo-Direct-Interface/dp/B001032GK8/

Worth a try. At least it'll point to a grounding issue if it helps.

 

[2muchstuff]

Worth a try. At least it'll point to a grounding issue if it helps.

True, but there is no remote output on the NAD. If it is a grounding issue, can we do anything about it?

 

[raindance]

True, but there is no remote output on the NAD. If it is a grounding issue, can we do anything about it?

You've completely lost me. Too many variables and no logic; does not compute.

 

[Joe0429]

In the past few months of discussions about ZA3, some users have reported that the 12V trigger function only works properly with a mono cable.
I haven't had any problems using a stereo cable myself.
Perhaps you could try using a different cable to see if it makes a difference.