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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
wynnroulette OP
4 posts
 
I have since went with a rotel pre amp and the hum was eliminated
Thank you all for your responses.
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.
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.
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.
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
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