Hissing sound - help trace the source

[Sylar]

I have a Marantz 7005 receiver and PSB T6 speakers. Of late I have been getting a hissing sound which is quite low in volume, but easily observable when sitting down.

Here are my observations...
1. Zero volume and on full volume it exists.
2. Around full volume the intensity is a bit higher. But the hissing intensity dosent change mostly when I change the volume, except after 90%.
3. When muted, there is no hissing.
4. I have a PC connected, i mute PC volume and observe hissing continues to exist.
5. This is interesting. I changed input source to other sources (most of which are not even connected), and the hissing still exists.
6. As I am writing this, i noticed the hissing has reduced much in its intensity. This happens sometimes. But the hissing comes back.
7. All speakers have it. I noticed the intensity is higher in tweeter and a lot lower in mid range driver.

Edit:
8. Oh Boy. Here is something that is really weird. With PC on mute, i open some movie using VLC and I get the hissing in louder intensity. And I close the VLC and hissing goes back to lower intensity. I unmute and observation is same. (Just like I mentioned in #6). I further switched off the TV and this behaves same.

 

[RichB]

^^^
I had a hissing noise with my AV8801 and it turned out that the plug was not well seated in the back of the unit.
I also had a trigger failure so when it was repaired they replaced the receptacle as well.

- Rich

 

[agarwalro]

I suspect your PC input has a noisy signal that is being picked up by the amplifier section. How is it connected?

Let's be thorough. To troubleshoot the source of interference, start by disconnecting everything (including AM, FM antennas) except speakers. Now connect sources back one at a time, keeping all others unhooked. This way the source of interference can be pinpointed.

If you receiver makes the hiss with nothing plugged in, your AC power may needed investigated. Alternately, you might have noisy EM background being picked up by the amplifier section.

Hopefully, the speakers do not hiss with nothing connected to the receiver.

 

[TLS Guy]

I have a Marantz 7005 receiver and PSB T6 speakers. Of late I have been getting a hissing sound which is quite low in volume, but easily observable when sitting down.

Here are my observations...
1. Zero volume and on full volume it exists.
2. Around full volume the intensity is a bit higher. But the hissing intensity dosent change mostly when I change the volume, except after 90%.
3. When muted, there is no hissing.
4. I have a PC connected, i mute PC volume and observe hissing continues to exist.
5. This is interesting. I changed input source to other sources (most of which are not even connected), and the hissing still exists.
6. As I am writing this, i noticed the hissing has reduced much in its intensity. This happens sometimes. But the hissing comes back.
7. All speakers have it. I noticed the intensity is higher in tweeter and a lot lower in mid range driver.

Edit:
8. Oh Boy. Here is something that is really weird. With PC on mute, i open some movie using VLC and I get the hissing in louder intensity. And I close the VLC and hissing goes back to lower intensity. I unmute and observation is same. (Just like I mentioned in #6). I further switched off the TV and this behaves same.

Disconnect all sources. If you hear the hissing then, you have a noisy solid state device. If it is all channels it probably is the DAC. Do you still get the hiss on in pure direct with digital processing and video circuits out of the equation? That will tell us whether this problem in in the digital or analog circuits. I'm betting since this is all channels, it is a digital circuit fault. However it might have a custom multichannel op amp chip that has gone bad some place.

If this problem is in the receiver, do a factory reset. I doubt it will help, but you never know.