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Suncoast Audiophile Society Message Board Main discussion area (visible to non-members) › Plasma TVs and Toroidal Transformers

Plasma TVs and Toroidal Transformers

Philip R.
inline_phil
Brooksville, FL
Post #: 74
After lusting over a plasma TV for several years we finally took the plunge and auditioned the Samsung UN64F8500. To my dismay as soon as we turned on the set the two toroidal transformers in our audio system started behaving strangely. A faint 60 Hz hum grew over about 5 seconds to a larger buzz and then diminished after 5 more seconds to a faint hum again. As one transformer grew louder thre other grew quieter. Two sets exhibited identical behavior and removing either transformer retained the behavior in the one that remained.

Has anyone else experienced this? Note that the hum/buzz was NOT coming from the speakers.
Russ G.
user 13947780
Sarasota, FL
Post #: 27
We have a Panasonic Plasma in the same room with our audio system with no problems. The audio is on a different circuit.
Dusty D.
user 37253042
Tampa, FL
Post #: 12
The use of a 1:1 transformer on either the audio or TV circuit is one option (old school)
Philip R.
inline_phil
Brooksville, FL
Post #: 75
The use of a 1:1 transformer on either the audio or TV circuit is one option (old school)
Usually true but one of the buzzing transformers was a hospital grade balanced isolation transformer (PowerVAR ABC1200-11).

Moving the TV to the primary side (same circuit) did nothing.

Moving the amplifier and line conditioner further from the TV reduced the effect but it did not eliminate it.

See what a standard AM radio does in response to a plasma TV here (yikes!)

This appears to be a problem created by the plasma process itself that is radiating through the air to the transformers (aka RFI).

Russ, how far away is your audio gear from the TV?
Jim M.
user 12404749
Sarasota, FL
Post #: 24
I have no problems either. Plasma TV is on the wall above the stereo.
Panasonic Plasma as is Russ's unit.

Jim
Philip R.
inline_phil
Brooksville, FL
Post #: 76
I have no problems either. Plasma TV is on the wall above the stereo.
Panasonic Plasma as is Russ's unit.

Jim
Now I'm really confused and perplexed. Let's explore another possibility.

I substituted another amplifier (Onkyo M-504) and disconnected the line conditioner. The buzzing was not present under these conditions. The Onkyo uses I-E core (rectangular-looking as opposed to round) transformers.

Do any of you who have plasma TVs in your rigs also have a power amp or line conditioner using toroidal transformers? BTW, my OPPO and my pre-preamp were not humming, low-current devices, and it appears that it may be a current related issue.
Jim M.
user 31555362
Saint Petersburg, FL
Post #: 2
My Panasonic Plasma doesn't affect any of my audio.
Russ G.
user 13947780
Sarasota, FL
Post #: 28
The amp for the stereo system is about 30" below the TV. Not sure what type of transformer is in the Bryston, as I've never opened it up. The rest of the system is at least 5' away.
Philip R.
inline_phil
Brooksville, FL
Post #: 77
The amp for the stereo system is about 30" below the TV. Not sure what type of transformer is in the Bryston, as I've never opened it up. The rest of the system is at least 5' away.
My amp is about the same, maybe 6" closer but that should be moot.

Which Bryston model is it?
Craig
user 14104710
Tampa, FL
Post #: 24
I've been using a 60" Pioneer Pro-151FD Plasma for a few years and have never experienced any 60hz hum issues.

I also have an AC Line Noise and EMI "Noise Sniffer" that I bought from Sound Advice when they were clearing out all their merchandise and equipment just before they shut the doors. It's a tool the salesman would use to demonstrate the effectiveness of a power conditioner. This morning, I placed the Noise Sniffer next to the screen to see if it would pick up any EMI noise and it was relatively quiet. The sensitivity is adjustable and will definitely pick up any EMI or AC Line Noise if it's there. I have everything is plugged into a modest Panamax conditioner but I have no idea if this conditioner is transformer based.

You're welcome to try the noise sniffer if you think it will provide any clues.
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