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"Amplifier Noise Floor" and hum acceptable?

I recently purchased the Parasound A52+ (5 channel amplifier, 180 wpc all ch driven). Initially I loved it and had no issues. About 2 weeks in however I was sitting around quietly and noticed the dreaded 60 hz hum. I get up close to the speaker midrange driver (Focal Aria 936) and there it is blaring at me. It is present in all 5 speakers I have connected. Everything is connected on a single dedicated receptacle with a power conditioner.

Trouble shooting.. the hum is not affected by volume control on the preamp. When I have removed the XLR cables to the preamp and ONLY have the speaker cables and the power cable connected... it hums. I did recently change my receptacle from a stock to a Hubbell but I don't think this would affect it. I upgraded my power conditioner too to see if that would do anything (I didn't think it would) and it did not. I switched the parasound out for a class D amp (120 wpc) and there was almost no hum. I switched it out for another class AB amp (140 wpc) and there was a hum but about half the volume of the parasound. 

So here's the gist.. when I emailed parasound tech support there are 2 things he said that I thought were noteworthy. One, he states that it is typical and normal to have some hum that close to the speaker baffle, i.e. within 1 foot of it. Second, while I asked for help he ultimately just said "I think you are just hearing the amplifier noise floor".

Three questions I pose to the community. 
Is it normal to hear a hum next to your speak baffle?
Is it acceptable and normal to be hearing the "amplifier noise floor"?
What can I try to lower this noise floor? I thought about connecting a ground wire between the chassis of the A52 and my power conditioner as the next step...

Thanks in advance for input.
jwl244
helomech
1,680 posts
 
https://parasound.com/a52+.php

Based on the specs linked above, there is absolutely no way you should be hearing hum a foot away, even despite your speakers higher than average sensitivity. A slight hiss with your ear to the tweeter is the most you should hear.

I had a similar issue with the Halo Integrated, though I could hear the hum from my listening position approximately 9’ away.

I’d demand a repair, or refund if possible. No way the amp is meeting that alleged spec, and no $3K amp should exhibit such noise. Simply unacceptable.
kijanki's avatar
kijanki
4,428 posts
 
My Rowland model 102 (class D) - absolutely perfect silence.
My Benchmark AHB2 - absolutely perfect silence.

Both are silent even when listening in close proximity.  Audible 60Hz is not acceptable IMHO.  Since you tried more than one amp it is likely something wrong with wiring (ground loops?).  I would take it to another location (friend) and try it there.  
lowrider57's avatar
lowrider57
5,417 posts
 
It's not acceptable to hear hum thru the speakers from your amp. It's possible that it's the grounding scheme of the Parasound, but before returning it, you need to check the grounding of your Hubbell duplex.
Pull the receptacle from the wall. Is there a metal box or plastic? 
Is the ground wire attached to a ground screw or a metal box? If using a metal box, the receptacle must be connected to it with a ground wire.

A ground fault tester will confirm proper grounding.
https://www.amazon.com/dp/B000RUL2UU/ref=cm_sw_r_u_apa_fabc_2A5ERAZ2Z0Y5P78X4C7T?_encoding=UTF8&...

Have you tried using a receptacle on a different circuit?


geof3
1,129 posts
 
Obviously no one is reading the post. The OP changed out three amps, all had hum, albeit to a different degree. So the problem isn’t the Parasound or any other amp, it is a problem with your power and the Parasound is more affected by it. Do you have any fluorescent lights, dimmers, led lights or other noise producing things on that circuit? Particularly dimmers... they are notorious. You could have a ground loop, you could have a faulty interconnect. Not an easy problem to nail down, start with any dimmers etc. they are the easy ones.
mofojo
2,297 posts
 
  If not too difficult do what I did. There was a teeny bit of drywall cutting involved but depending on your house layout may be easy peasy.

   Get dedicated 20a line from your box.

   Well worth the 500 it costs me . For sure. I had a small amount of static but could  not be heard from the seating position. After . None nada. Also it is better at higher listening levels when pushing things. Way more relaxed sound with better bass. I am knocked out by this 500 mod. My volume on dac to amp is about 6db higher on an everyday basis with 0 fatigue.  

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