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Parasound Halo Integrated Buzz/Hum

Hi all. I bought a Parasound Halo Integrated last week and discovered there is a faint low frequency buzz coming from my speakers from all inputs except the home theater bypass (more on that below). In a completely silent room I can hear it from my listening position about 8ft away from the speakers, but it's not very loud at all. After a quick Google search and some reading, the most likely cause seems to be a ground loop issue.

Unfortunately, I am not sure if it is as simple as that. I disconnected all inputs and plugged it in an outlet with no other devices connected. I also moved it to a different outlet in my apartment, again with only speakers connected, and it still buzzes. Different model speakers have been tested as well.

The buzz only comes from the speakers, not from the amp itself or if headphones are plugged in. This integrated amp has home theater bypass inputs and there is no buzz when this input is selected. However, if I connect my AVR to these inputs, there is a buzz. This buzz can also be heard through headphones connected to the Parasound. Unlike the buzz from other inputs, this buzz does not increase when I increase the volume.

My apartment is in an old building, which in all likelihood had its wiring redone over the past decade or so. I used a 3 wire receptacle tester on some of the outlets. It indicates there is an open ground in my living room (something I should probably bring to my landlord's attention!), but other outlets appear to be wired correctly. The buzz is there regardless of what outlet I use, however.

The amp was bought from an authorized dealer and I am still under warranty, so I can certainly get it replaced or repaired. Before I do that, however, I would like to make sure I have exhausted all of my options. Do any of you knowledgeable folks have any idea if I am missing something? 
tod_

Showing 5 responses by helomech

helomech
1,489 posts
 
I had a Halo Integrated and experienced the same issue. I used 6 different pairs of speakers with the amp, in addition to different outlets, cables and source components. I also checked the ground points inside the amp. The noise always remained at the same level, however, it was low enough that it was rarely noticeable during playback.

 The only other amps I’ve had in my system that produced similar noise were all 3 Rogue Audio integrateds. My experience led me to believe that it’s in the nature of the H-Int’s design, not a QC issue.
helomech
1,489 posts
 
AC power quality is not the issue. I’ve worked in mitigating ground loop and EMI noise in avionics for years, and I’m sorry to say the problem is in the amp. The AC coming into my home is as clean as any. I checked the internals of my Halo Integrated thoroughly and I could only conclude that the amp has a less-than-ideal circuit layout or connection issue that would require extensive disassembly to find.

If you Google some internal pics of the H-Int, you’ll notice there’s some variation to the wire routing. I know they also had a rash of bad volume pots in some of these amps (though that’s not the culprit in this case). So I’ll retract my prior statement and say that it is potentially a QC issue, but I think it’s far more likely that they simply revised portions of the design/layout at some point.




helomech
1,489 posts
 
^ Did they fix the problem?
helomech
1,489 posts
 
If your Denon AVR has a two prong cord, that’s likely why it’s silent compared to the Halo.

I think there’s a few manufacturers that expect customers to accept hum since of it’s not audible during playback. I’m not surprised by the tech’s initial response. That was basically his way of saying it’s acceptable within their normal QC parameters. Some claimed to have gotten similar responses from Rogue. I’ve had 3 of their integrateds in my system, and all hummed to some extent.
This was one of the factors that led me back to Yamaha.

Good luck. I hope they can sort it out.
helomech
1,489 posts
 
Glad they took care of you. Thanks for the update.
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