2. amps-preamps
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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
geof3
1,129 posts
 
Once again, you’ve got another problem somewhere in the chain, bad cable, funky power etc. Time to go deep and look at your electrical system, most importantly that particular circuit. An easier way to troubleshoot the Parasound is to take it and put it into a different circuit, use an extension cord, or move it to another room on a different circuit with a pair of speakers of some sort.

Someone mentioned a sub, that could be a part of the trouble too. At this point it is unlikely the Parasound.
jwl244 OP
64 posts
 
Same hum with subs disconnected. 

Tried hum x which didn't help which I figured since the ground lift didn't either. 
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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