Excessive noise in subwoofer out

Nordskov

Member
2007-06-18 11:42 am
I have a Marantz SR6010 AVR.
Some time ago I fiddled with the Internet Radio and switched to Online Music.
Suddenly there was a very loud persistent squeel in the speakers. I didn't touch anything but the remote.
Luckily the volume were turned way down or I'm sure my tweeters would have been smoked.
My sub amp wasn't turned on at the moment.

Now I experience a raised noise level in the subwoofer output. About 6-10 dB louder I estimate. It is easily heard in quiet passages in music and movies.
It's low frequency white noise indicating it's induced before EQ.
There's no problems in the mains.

There's no problems with cables or the external sub amp.

Any suggestions on what might have gone south here?

Cheers,
Nordskov
 

Nordskov

Member
2007-06-18 11:42 am
First ... are you sure it's your AVR? It could be the new source device. What happens if you use a different source?
Hi Douglas.

I did a good deal of troubleshooting.

The noise is on every source.
It disappears when I disable subs.
It disappears when I shut off the AVR (sub amp still ON)
I tried a handful og cables. Still there.
It increases when I increase sub gain in the AVR
A funny issue is, the frequency profile dont shift when I change crossover point (40-250 Hz). Not to my hearing that is. That is odd, I would expect that.
 
Hi Douglas.

I did a good deal of troubleshooting.

The noise is on every source.
It disappears when I disable subs.
It disappears when I shut off the AVR (sub amp still ON)
I tried a handful og cables. Still there.
It increases when I increase sub gain in the AVR
A funny issue is, the frequency profile dont shift when I change crossover point (40-250 Hz). Not to my hearing that is. That is odd, I would expect that.

I am not the AVR specialist you need.

But it seems to me the problem is likely in the subwoofer output someplace, you'll need schematics to troubleshoot it further.

I wish you good luck in fixing it...
 
Hi Douglas.



I did a good deal of troubleshooting.



The noise is on every source.

It disappears when I disable subs.

It disappears when I shut off the AVR (sub amp still ON)

I tried a handful og cables. Still there.

It increases when I increase sub gain in the AVR

A funny issue is, the frequency profile dont shift when I change crossover point (40-250 Hz). Not to my hearing that is. That is odd, I would expect that.



Give this a try. Do you have any computer power cables without the 3rd ground lug?
Or try using all power cables with the 3rd ground lug and then without !
On my last Marantz preamp I had would have noisy sound when I used a cable with the ground lug on the power cable. And yes all my home wiring had the earth ground and only my Marantz pre had the noise proble when using a grounded cable
Sounds stupid but it worked. And after a figured that issue out I added a ground strap to the outside of the unit to one of my amplifiers so that the system was still grounded but for some reason with the grounded cable it had noise in here in Florida we have a very dirty and unreliable power grid
 

Nordskov

Member
2007-06-18 11:42 am
Give this a try. Do you have any computer power cables without the 3rd ground lug?
Or try using all power cables with the 3rd ground lug and then without !
On my last Marantz preamp I had would have noisy sound when I used a cable with the ground lug on the power cable. And yes all my home wiring had the earth ground and only my Marantz pre had the noise proble when using a grounded cable
Sounds stupid but it worked. And after a figured that issue out I added a ground strap to the outside of the unit to one of my amplifiers so that the system was still grounded but for some reason with the grounded cable it had noise in here in Florida we have a very dirty and unreliable power grid
I dont have ground in any of my sockets.
I think in my town we have a pretty clean power grid.
I didn't do anything to the mains power at the moment the noise got worse.
I think something got fried, but I dont know where.
And I dont know why it made that squeal in the first place.