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Discussion Starter #1
Hello,

I was hoping I could get some advice from my fellow AVS forum members on a strange issue I am having in my theater. I am getting a intermittent static noise from some of the channels. The first time I noticed was from the surround backs (Paradigm Millenia 30 on walls), I was convinced the speakers were just blown so I replaced the blown drivers as the static seemed to be coming from the upper woofer of each speaker, I did not use the theater again until the replacement parts came in and I replaced and all seemed fine, several weeks later I was in the theater listening to music and experienced the same static, this time from the left front channel, so I assumed another blown woofer (I do drive my system hard at times but never beyond ref level, when I am pushing hard I am at -5db tops) . I again purchased a new woofer and replaced...fired up the system and the static started in again almost immediately from the same channel, this time I noticed it was coming from all the drivers within that channel, in other words the static was coming from the woofers and tweeters incased in the left front speaker (multiple driver speaker). I am trying to narrow down the source of the static, It first happened from an Apple TV and this time it was Tivo , so I doubt its the source components, its also different amps, the front left is powered by an Outlaw m2200 while the rear surrounds are powered by an emotiva XPA5, I am using a Yamaha RXA2020 as a pre, So I am thinking it must have something to do with the receiver preouts or perhaps wiring interference. If anyone has experienced this I would appreciate any guidance. What concerns me is that this happened on now three separate channels and two different amps, and its intermittent. the static is quite loud and as you can imagine annoying. I will begin by replacing speaker wire and receiver to amp interconnects...but I am unsure why it would be intermittent which is why I am thinking it could be interference from another powered source that too close to the speaker wire...or the Yamaha is no good which I also find unlikely since its not that old.

any suggestions/helps greatly appreciated

equipment:
Sony HW40ES
Elite 120" fixed screen
Yamaha RX A2020
Outlaw Audio M2200 x4
Emotiva XPA5
Paradigm Millenia 20's (front left and rights, surround back left and right)
Paradigm Millenia 30 center channel
Boston acoustics VRMX Front left and right heights
Boston acoustics bravo II surround left and right
Apple TV
Tivo Premier
Playstation4
a ton of network gear is in the rack as well

thank you
 

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Intermittent problems are hard to diagnose/find.

Start simple and try to find the "problem" by process of introduction.

As you already know, the problem could be speaker wire(s), interconnects, pre-amp, amps, source hardware, etc... or, something is continually (electrically?) making stuff go bad.
 

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Can you describe what the noise sounds like in more detail? Is it a crackling/popping sound?

Does it seem to be temperature sensitive? Take a hair dryer and put it on the vent of the Yamaha and run it on hot for a minute or so. Does it get worse?

Alternatively get a can of freeze spray. Open the top of the Yamaha and squirt all the PCBs good (stay away from the power supply). Does it get worse or better?

Most likely thing is as you guess the pre-amp in the Yamaha going bad. Static bleed into the speaker wires, etc. is very rare to be the cause. Intermittent cracking/popping noise is almost always transistors/ICs going bad.
 

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Discussion Starter #4
Its certainly a crackling popping sound, I have had some slight issues with the Yamaha shutting down on its own a few times, I added exhaust cooling and this seemed to reduce the incidents of shutting down but it has happened a few times even with the fans on, I have a temp sensor on the top of the Yamaha and during normal operation it runs at about 105 degrees F, the fans kick on at 85 but the fans don't bring it down much lower than about 100, I do not believe this is too hot but it is possible that it got much hotter prior to the fan install and perhaps the first shutdown was enough to cause damage to the circuitry, the component is in a cabinet with an open back and perforated door (salamander synergy) but its also surrounded by amps (Emotiva XPA 5 on top and 3 Outlaws under with very little air flow prior to the fan install. I suspect it is the Yamaha causing the issue and not interference...
 

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If it is crackling/popping sound, then I am confident it is a transistor (by itself or inside of an IC) in the pre-amplifier failing. Such failures could be running too hot for too long or could just be a bad component. The technique I described is how technicians find such faults. If a technician is old school, they should be able to find the component and replace it. If not, they would want to just replace the whole board which with labor could set you back a few hundred dollars. In that case, if you have been eyeing a new AVR, this may be the time to get it :).

On cooling, if the unit is shutting down, then that is a sign that it may be overheating. The key temperature is the transistor junction. Unlike computers where there is internal instrumentation for the CPU/GPU core, there is no such thing in audio electronics. While it may be 105 degrees in air around a transistor, the junction could be at far higher temperature depending on the heat sink and cooling. The temperature sensor in the protection circuit is usually conservatively rated to shut down the unit before damage but continued high temperature operation will reduce the life of the electronics and can cause a borderline part to fail.
 

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Discussion Starter #6
I tend to agree with your assessment, I will try the hair dryer test as you mentioned and see if I can duplicate the issue and narrow it down to the Yamaha, I was not looking to upgrade until another year or two when Atmos, or other immersive audio formats plus an HDMI standard was sorted out. I might purchase a interim Pre from accessories for less or another RXA older model until then.

thank you for your input
 
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