2. tech-talk
  3. 1040565668

How to eliminate system hum?

I have the following
Rotel 1090 amp
Hovland Pre-amp
Sony 777 CD player
Shahinian Speakers
I have this irritating hum/hiss when I turn on the pre-amp. The sound comes from the speakers when the pre-amp is turned on. If the pre-amp is off and the amp is on, the system is totally silent. It seems as if the amplifier is ok. It seems to be doing its job and is amplifying the crappy signal it is receiving.
Thinking my home electric was poorly configured, I had my electrician install a panel and dedicated lines for my system. The problem is now worse!
I don't think the pre-amp is to blame as I had the same problem with my previous pre-amp. I also have a new cd player.
I have read about "floating" the system ground by using 3 to 2 prong adapters on all system power cords. Is that what I should try?
If anyone has any ideas, I'd be very appreciative. Having $20k worth of stuff that sounds bad is no fun!
holzhauer
holzhauer OP
201 posts
 
Sean:
I read your entire noise hum and polarity post. You receive an A+ in my grade book. I think you qualify for the honorary Phd in hi-fi. How long have you been doing this?
P.S. The owners manual for the CAT SL1 ultimate had a similar discourse. Just not as detailed. I bought a VOM today.

A1126lin: 3/2 adapter is a $0.39 hi-fi component at Ace hardware! The female end takes the 3 prongs from your power cord. The male end eliminates the ground and has only two prongs.
Floating refers to having only one of your components hard grounded to the outlet. The others have 3/2 adaptors and ground via the interconnects.
sean
6,231 posts
 
Holzhauer: I'd like to take credit for the info in that post, but i can't. This info has been available via several different sources and i simply made it available here on Agon for those that may have never run across or heard of such things. While doing so, i tried to take into account that many people that frequent these forums are not technically inclined, so i tried to break it down step by step. Hopefully, doing so has made it easier to follow along with and might help others to solve a problem.

As to how long i've been into "hi-fi", i had my first "real" system when i was 13 years old and am now going on 39. I grew up with a Father that had owned a component audio system for as long as i can remember. As such, i had a bit of a head start and the fact that i'm technically inclined hasn't hurt one bit either : ) Sean
>
a1126lin
70 posts
 
thanks for the advice
i try the 3/2 adaptor on my nak ca7 preamp and it reduce the humming at least 50%. there is no humming coming from the amp. what else can i do to eliminate the humming completely.
holzhauer OP
201 posts
 
A1126lin:
Try 3/2 adapter on all 3 prong components except the pre-amp.
a1126lin
70 posts
 
thanks for the advice , it took care of the humming completely.
More to discover