2. amps-preamps
  3. 164809-139231

"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
anilpani
1 posts
 
I know this post is a few months old, but wanted to say that I recently acquired a Halo A51 and have the same issue as the original poster. Prior to this I had a Rotel RMB-1075 which was silent.
The hum I have is audible from the unit itself once powered on and the sound is transmitted to all five speakers even when the receiver is completely disconnected from the amplifier. I have called Parasound for their advice, but seems like they may not have much else to offer.
audiowjr
1 posts
 

Reviving an old post:

I have an A52+ Parasound amplifier, and I love it’s sound, but it has started making a hum in channel 1 that is very noticeable from the listening position (accross the room.) Replacing the amp with another amp and the system is dead quiet. The A52+ makes the noise with no inputs connected, just a speaker connected. This noise is still present using a different power outlet.

The Parasound technical support says this: "It sounds like the normal noise floor of the amp. Channel 1 and 2 will have slightly higher noise than 3-5 because of the proximity to the power supply. If your speakers are higher sensitivity than average (above 90db) it will be more noticeable."

I think that is totally unacceptable. Going to take it back and try and get it fixed. It’s still under warrantee. I hope to get a better resolution than "that’s the way it is".

bacobits1
103 posts
 

Do you have a cable tv setup box etc?

Check it , disconnect it, they do not ground correctly on installation.

I run 10 tubes in my Cronus Mag ll and alternative

 Croft I have zero him of any kind at 90db speakers at the speakers.

 

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