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Do preamp processors produce a slight hum .

I have unhooked quite a few things from my audio rack but the last thing was a VCR/DVD recorder not being used. I run a Comcast cable thru a Panamax surge conditioner than thru a mondial magic box then to cable box than to a old 40 tube tv.I have noticed a slight hum if you stand very Very close to unit,the processor is a 15 year old acurus act3. I have never paid any attention to this before. The only thing I have hooked up is a 5 Channel
Rotel amp, and a blu ray also in the panamax next week I will be replacing the acurus with a rotel 1068 processor so I hope I will not have any problems. I suspect this is probably normal but would like some advice from someone more
Knowledgable. Slight hum is When all equipment is off in a very quiet room and wondering is this going to happen with the rotel. Thank you
wynnroulette
5 responses Add your response
dancewithethan
8 posts
 
I used to have same issue, went out and got a good wall outlet ground checking device. it turns out my wall ground came loose, and many others around the house. Got it fixed, and the hum went away. Also, a good AC conditioner helps.

Best
internetmin
258 posts
 
Where is the hum coming from? If it is coming from the Pre-pro itself then you may have an issue called DC Offset. It's usually caused or exacerbated by dimmers in the house or a particular appliance or a combo of other factors. The bottom line is you need a unit to take the DC off the line. PS Audio had a unit called the him buster that did just that. They no longer make it last I checked.

Emotiva started selling a unit to deal with DC Offset. You will find it here;
http://shop.emotiva.com/collections/accessories/products/cmx2

If the hum is coming from the unit and specifically the transformer area it's likely DC Offset.
pdn
438 posts
 
Just taking a wild guess. Do you have one or more sub-woofers and if so, could it be eminating from them? I have two subs and had a hum problem until I went with Audioquest sub-woofer cables which have ground wire horseshoe connections. You simply connect the ground wire to a grounded screw on the sub. Also consider installing PSAudio Power Ports and other PSAudio filtering products. Just some ideas.
kr4's avatar
kr4
3,649 posts
 
First, it ain't a common feature of prepros but it is a common problem with cable boxes. These are often installed with improper grounds, i.e., remote from the main house ground resulting in a ground loop. Relocating the cable ground to the main ground is a common fix. You can test this by disconnecting the input to the cable box.

Otherwise, normal ground sleuthing is recommended.
wynnroulette OP
4 posts
 
I have since went with a rotel pre amp and the hum was eliminated
Thank you all for your responses.
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