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Premium Member
76 Posts
Discussion Starter #1
I am stumped about a hum when watching a light-colored image on my 65VT60. I've read about humming plasmas, ground loops, bad transformers, and so forth, but this hum is coming from my front speakers. I am unsure where to start diagnosis, because the hum does not come from the transformer area, but rather from the tweeters in my front external tower speakers. No recent changes in settings or hardware. The system is about a year old, this issue started about a month ago. I wonder if the receiver or speakers are getting some current induced from the plasma, and plan to eliminate every possible source one at a time, but wondered if you had any ideas that might aid the diagnosis.

Denon AVR-X4000
Onkyo M-5130 (driving front wides)
Panasonic VIERA 65VT60
SVS Dual-PB12-NSD, a pair (supporting the fronts)
Pioneer Andrew Jones SP-FS52 fronts, SP-C22 center, SP-BS22 front wides and rear surrounds
Cambridge SoundWorks DiPole rear center
Sony Blu-Ray, Toshiba HD-DVD, MiniMac
Audio and video calibrated by ChadB
Samsung SMT-H3272 whole-house cable box/DVR from Time Warner
Arranged in a normal 8.2 layout, tower speakers flanking the display, but moving them 3 feet away does not help

I took out the UPS's powering the Denon and Panasonic, thinking the approximated sine wave might be the issue. I have a Monoprice power conditioner powering peripherals coming out next. Then I plan to remove all inputs save the cable box. I am getting much pixelation and such with it, as if it were also affected by some radiating field, ground loop, current anomaly, or signal distortion, and will swap the same model from another room to see if that issue follows it.

It seems like the plasma is inducing some field in the receiver or something, since the tower speaker's distance from the plasma does not seem to affect the issue. I'm wondering if I have some power issue or radiation gone wild, but hardly know where to start other than taking the whole system apart and adding one component back at a time (ugh). If you have any rifle shots rather than that shotgun blast approach I would love to hear it. I'd make a service call to Panasonic if the hum was coming from the TV itself, but it's coming from the external front speakers. Thanks in advance.

HTS Senior Moderator
5,423 Posts
My Denon/Sony combo does this too, but only when I have analog video cable hooked up for the OSD. Dunno why. Since my Denon does not have HDMI I run the audio through the TV, HDMI from Blu-ray and Dish Network to TV then TOSLink to the Denon, then utilize the pre-outs to Acurus amps. Don't really need the OSD so I've never really dug into it.
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