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Post by quattroll on Feb 23, 2022 22:56:03 GMT -5
Hi Lounge,
I have a problem that I need some advice on. I have discovered that my 65 inch 1080P Panasonic Plasma from 2013? (high end at the time) is making noise on my AC line in my living room with a 5.1 setup. I have deduced that it is the TV itself creating noise(hum) in my SA-250 powering the fronts. This despite having a Audioquest Niagra 1200 and a Panamax PF something or other. I have been living with some hum from the TV I thought for a while, which manifests when it is a bright picture, presumably because more energy is needed. I am not against a new set, it's just that the picture is still quite good despite the non 4K.
I discovered that the noise is on my rear channels in a pronounced way when I decided to switch from PA-1s to a Mini X. I did this to "save" the PA-1s which I think are pretty special. I first thought that it was the unbalanced connection, but it turns out to be the TV. I have deduced this by turning off the TV, and every time the noise goes away. More seriously though is the fact that it makes my SA-250 hum in a pulse that lasts for maybe 10 seconds on and 10 off. I plugged the TV into the wall outlet, bypassing the power filters, and to my surprise it was still there. I moved the SA-250 to another room and unconnected but powered up, and it seems to emit a little noise, but it is now constant, so that seems normal. In the meantime, I have gone 2.1 with the PA-1s and they don't hum for now. So the noise was making its way to the rear channel speakers, and it was making my SA-250 hum inside as well.
Now the question is: Is my TV a liability at this point? I have never had anything that could put noise back through the wall to another outlet, but that is what is going on as far as my testing shows. What do you guys think? Is this a time bomb for the rest of my electronics?
Thank you to all in advance.
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Post by jbrunwa on Feb 24, 2022 1:10:28 GMT -5
Hi Lounge, I have a problem that I need some advice on. I have discovered that my 65 inch 1080P Panasonic Plasma from 2013? (high end at the time) is making noise on my AC line in my living room with a 5.1 setup. I have deduced that it is the TV itself creating noise(hum) in my SA-250 powering the fronts. This despite having a Audioquest Niagra 1200 and a Panamax PF something or other. I have been living with some hum from the TV I thought for a while, which manifests when it is a bright picture, presumably because more energy is needed. I am not against a new set, it's just that the picture is still quite good despite the non 4K. I discovered that the noise is on my rear channels in a pronounced way when I decided to switch from PA-1s to a Mini X. I did this to "save" the PA-1s which I think are pretty special. I first thought that it was the unbalanced connection, but it turns out to be the TV. I have deduced this by turning off the TV, and every time the noise goes away. More seriously though is the fact that it makes my SA-250 hum in a pulse that lasts for maybe 10 seconds on and 10 off. I plugged the TV into the wall outlet, bypassing the power filters, and to my surprise it was still there. I moved the SA-250 to another room and unconnected but powered up, and it seems to emit a little noise, but it is now constant, so that seems normal. In the meantime, I have gone 2.1 with the PA-1s and they don't hum for now. So the noise was making its way to the rear channel speakers, and it was making my SA-250 hum inside as well. Now the question is: Is my TV a liability at this point? I have never had anything that could put noise back through the wall to another outlet, but that is what is going on as far as my testing shows. What do you guys think? Is this a time bomb for the rest of my electronics? Thank you to all in advance. If the noise is transmitted over a power or audio cable, a set of choke ferrite beads placed on all the cables on the TV and/or on the amp may help. |
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Post by garbulky on Feb 24, 2022 7:12:45 GMT -5
Doesn't Emotiva's CMX-2 tackle this?
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Post by rbk123 on Feb 24, 2022 9:07:16 GMT -5
Try the chokes first like jbrun suggests. Also, get a decent power cord and plug the tv into another outlet that is on a completely different circuit breaker and see if that changes anything.
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Post by quattroll on Feb 24, 2022 22:17:55 GMT -5
Thanks for the responses. I have had a little more time to experiment, and it definitely is the TV contaminating my entire system. Yes I was using a power cord with chokes, and I also tried other outlets but due to my room layout I can't have access to another breaker circuit. Garbulky is right, the CMX-2 does take care of this. I have one in another room where it arguably is not needed and plugged the SA-250 in on its own, and the throbbing hum disappeared. So it must be DC offset. Interestingly, the CMX-2 does not shield the rest of my system. So, for example, if the TV is plugged into the wall, and the CMX-2 is before my Niagra 1200, it will not remove the throbbing hum which is heard on the rear channel speakers, and the SA-250 transformer. If I plug the TV into the Niagra which is plugged into the wall outlet (understanding that it is making all the noise) and I plug the SA-250 and MiniX to the CMX-2 which is coming from its own wall outlet, then the problem is gone. Now the issue is I really need more than 2 outlets, so I need a CMX-6 too! Not to mention how good can the Audioquest Niagra 1200 be if it somehow finds the noise after the CMX? None of this makes much sense, but for the time being, I have removed the noise on these amps. The PA-1 on my center is plugged into the 1200, where the noise is with the TV, but is somehow immune from this problem. I wonder why, by hey it works for now.
I'll bet this will all go away when I buy a new TV, maybe it's just my system saying it's time to upgrade!
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Post by audiosyndrome on Feb 24, 2022 22:56:15 GMT -5
Try changing the flux capacitor before a new TV. 😅
Russ
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Post by leonski on Feb 24, 2022 23:16:20 GMT -5
Plasma...at least the last of the Panasonic sets, were some of the best ever made up to that time. They stole some of the KURO engineers from I think....Pioneer.....when that line closed.
Too bad the cells on a plasma get too small for 4k....so that's a non-starter.
I HAD an S30 Panny and for the time, it was pretty good. Later ones got better. BUT? It used a LOT of energy and you could feel the warmth from above the set as it wafted up.
My advice? Take your set to a fix it guy. Pay for an Estimate and if it exceeds maybe 25% of the same size LG OLED set? Junk it out. You'll go positive on the electric bill immediately and
in summer your AC will thank you.
My OLED is terrific and B6 and maybe 5 or so years old......Off-angle viewing is epic. In a dimmed room, you simply can't beat this image....
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Post by quattroll on Feb 24, 2022 23:51:09 GMT -5
Thanks Leonski, that is good advice. This TV is on a lot and Iv'e never really known how much electricity it uses. I just am reluctant to send something to the landfill, that still "works". I think that that this set is probably going to fail sometime soon because after 9 years, this is definitely a relatively new problem.
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Post by rbk123 on Feb 25, 2022 15:18:59 GMT -5
I don't believe the CMX-6 has the DC offset, I believe it's only the CMX-2 so make sure you confirm with Emotiva.
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Post by leonski on Feb 25, 2022 15:53:36 GMT -5
Probably an issue with the set....rather than the catch-all of 'DC Offset'......... you could try, for example, a next level diagnostic by unplugging / disconnecting other parts of the interconnected system. Unplug than REconnect if it isn't 'it' until you get to 'IT'...... I use OPTICAL, for example, as much as possible so ANY kinds of grounding issues are automatically avoided I've heard lots of stuff about SAt Dish Receivers being the source of some problems..... I don't know, but THIS may help? www.wikihow.com/Measure-DC-Offset |
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KeithL
Administrator 
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Post by KeithL on Mar 15, 2022 0:13:39 GMT -5
DC Offset is a very specific issue... DC offset itself is not audible (since it is DC)... The reason DC offset causes audible noise is that it causes excess current to flow in the primary windings of power transformers - especially toroidal transformers. This often causes the transformer to run warmer, which, for a variety of reasons, causes it to produce more mechanical hum. (And, if there is enough offset, it may actually damage some transformers, or cause them to run excessively not.) To vastly oversimplify, a plasma TV is comprised of a huge number of what may be thought of as tiny fluorescent bulbs, or even tiny neon bulbs. And, in each cell of the plasma screen, there is what amounts to a tiny electrical arc when the cell is lit. Each of these tiny arcs is microscopic but, because they all "fire" in synchronism, they can collectively generate significant electrical noise. This noise can leak back into the power lines, but it is also, to a tiny degree, broadcast into the air... Where it can, in turn, be picked up by power lines, the circuitry in other equipment, or even by interconnect cables. (And, of course, the actual power supply of the TV can also be generating electrical noise.) Unfortunately, because there's so much going on, it can be difficult to track down where that noise is finding its way into other equipment... In general, a line noise filter will be much more effective at blocking noise from going through it, than at actually "eliminating noise". Therefore, putting the plasma TV on its own line noise filter may well help, and likewise using them on other equipment.
You should also consider trying to make sure that the plasma TV is on its own circuit. (A circuit breaker box does NOT specifically provide electrical isolation between circuits... but, especially at higher frequencies, separate circuits may provide some degree of isolation.) Another thing to try would be to make sure that the plasma TV itself has a SHIELDED LINE CORD. This isn't especially important for most gear... but it can make a big difference for equipment that is actually leaking noise into the power lines. (It prevents the line cord of the TV itself from acting like an antenna and radiating noise into the air where it can reach other cables or gear.) (You can check whether this matters by moving the TV's line cord around... if the noise changes when you touch or move the cord then it matters.) You may also find that simply moving the TV's line cord, and especially moving it away from other cables, may help significantly.
Probably an issue with the set....rather than the catch-all of 'DC Offset'......... you could try, for example, a next level diagnostic by unplugging / disconnecting other parts of the interconnected system. Unplug than REconnect if it isn't 'it' until you get to 'IT'...... I use OPTICAL, for example, as much as possible so ANY kinds of grounding issues are automatically avoided I've heard lots of stuff about SAt Dish Receivers being the source of some problems..... I don't know, but THIS may help? www.wikihow.com/Measure-DC-Offset |
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Post by ttocs on Mar 15, 2022 8:50:37 GMT -5
You may also find that simply moving the TV's line cord, and especially moving it away from other cables, may help significantly.
This^^^^. Cable management is very important. |
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Post by 405x5 on Mar 15, 2022 9:02:43 GMT -5
Hi Lounge, I have a problem that I need some advice on. I have discovered that my 65 inch 1080P Panasonic Plasma from 2013? (high end at the time) is making noise on my AC line in my living room with a 5.1 setup. I have deduced that it is the TV itself creating noise(hum) in my SA-250 powering the fronts. This despite having a Audioquest Niagra 1200 and a Panamax PF something or other. I have been living with some hum from the TV I thought for a while, which manifests when it is a bright picture, presumably because more energy is needed. I am not against a new set, it's just that the picture is still quite good despite the non 4K. I discovered that the noise is on my rear channels in a pronounced way when I decided to switch from PA-1s to a Mini X. I did this to "save" the PA-1s which I think are pretty special. I first thought that it was the unbalanced connection, but it turns out to be the TV. I have deduced this by turning off the TV, and every time the noise goes away. More seriously though is the fact that it makes my SA-250 hum in a pulse that lasts for maybe 10 seconds on and 10 off. I plugged the TV into the wall outlet, bypassing the power filters, and to my surprise it was still there. I moved the SA-250 to another room and unconnected but powered up, and it seems to emit a little noise, but it is now constant, so that seems normal. In the meantime, I have gone 2.1 with the PA-1s and they don't hum for now. So the noise was making its way to the rear channel speakers, and it was making my SA-250 hum inside as well. Now the question is: Is my TV a liability at this point? I have never had anything that could put noise back through the wall to another outlet, but that is what is going on as far as my testing shows. What do you guys think? Is this a time bomb for the rest of my electronics? Thank you to all in advance. The set is old enough where trying to remedy the trouble will be more trouble than it’s worth I fear…. |
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Post by leonski on Mar 15, 2022 15:18:48 GMT -5
What a crack up! You BET Plasma sets are noisy. I tested MINE with a very sensitive AM radio. At 15 or 20 feet? Forget it.
But noise even further interfered with lower powered stations. Even LATE at night when the SW bands clear some? That TV had
to be OFF to attempt any critical reception. Even if I stepped out back and strung a long wire antenna just for some listening.....
If you want to go FORWARD in your TV watching and the picture is more than a little important? Go Get an OLED set. They make 2 lines now or more and the entry stuff
is good but I'd guess BEST in a dimmer room. NOT in a bright / sun lit area. I think that LG makes ALL the panels which means Sony, Panasonic and maybe even Vizio and
others......I am not current. But I would go to the source and get LG.......I have personal problems with SONY and believe Vizio is more cheaply made. Panasonic Plasma was, at the end,
the BEST display you could buy but was Plasma.....
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