Jump to content

Help solving a loud noise problem


Recommended Posts

Hi all hoping to find possible answers to my issue by tapping the collective experience of the forum.

The problem:

When connecting and powering up a 2 channel power amp to the rear surround pre out of my avr via RCA I get massive hum/whine through the speakers that makes me fear for their survival. This also happens when I connect  it to the main L and R pre out via RCA.

However connecting the same  amp to a different pre amp via rca does NOT cause any noise and plays without issue.

Connecting a different power amp to either of the avr pre outs mentioned above also does NOT cause any noise to be heard.

So us it the amp or the avr or something else. I'm stumped

Any other things I can try to isolate it?

 

Link to post
Share on other sites

Are you Making sure the power amp is fully powered down, before you go unplugging RCA/XLR inputs?  If not get into this habit.   The last thing to power up in any configuration is the power amp.   

  • Like 1
Link to post
Share on other sites

Is the AVR power cable using the earth pin?

Is the power amp power cable using the earth pin?

Have you tried a different RCA cable?

It sounds like a ground loop type of issue.

Link to post
Share on other sites

What makes and models of AVR and amp are we talking about? Sounds like one is earthed (3 pin plug) and the other isn't (2 pin plug).

  • Like 1
Link to post
Share on other sites


Thanks guys. The avr is a Denon x4000 and the amps are bel canto S300 and S500. The S300 for surround duties is the one giving me headaches. I have tried different rca cables with no change. I have no idea about earthing but the 3 devices are all plugged into the same belkin board. During connection the power amps were powered on last. 

Link to post
Share on other sites

Oh and I did let the amps power down fully  before plugging/unplugging cconbections as the bel canto's have a noticeable "still powered" lag after switching off the units power switch. 

Link to post
Share on other sites

I was thinking it might be the S300 and avr not playing nice together as in grounding issues but it is so loud I thought the amp might be faulty as it is getting on in years but it works and sounds just fine driving my little pmc's in a separate system

Link to post
Share on other sites
43 minutes ago, BlackMX said:

Thanks guys. The avr is a Denon x4000 and the amps are bel canto S300 and S500. The S300 for surround duties is the one giving me headaches. I have tried different rca cables with no change. I have no idea about earthing but the 3 devices are all plugged into the same belkin board. During connection the power amps were powered on last. 

The S300 looks like a Class D amp - presume it only has a 2 pin plug. You could try a cheap stereo RCA ground loop isolator- not sure one of these will work as they're usually designed for relatively small ground potential differences.

Edited by Quark
Link to post
Share on other sites


Checking the manual for  the Belcanto s300 has a switch that lifts the ground for XLR/ RCA switch, is this what’s on the back of your model if so  the position for the RCA should have the switched so the button pushed in for RCA and out for XLR to lift ground.

 

https://www.manualslib.com/manual/15214/Bel-Canto-M300.html?page=6#manual

6B304457-2721-428F-94A4-519EDE12EF47.png

Edited by Addicted to music
  • Like 1
Link to post
Share on other sites
  • Recently Browsing   0 members

    No registered users viewing this page.




×
×
  • Create New...