HK 3490 hum

[cubazuelen]

I am using my HK as a pre out which runs to a crown xls2500 to power my mains. With just my crown on I have an almost inaudible hum(I have to put my ear almost touching the tweeter and then it is barely audible). When the HK turns on I get a large increase in this hum, it can be heard 8-10 feet away! Everything is plugged into the same outlet/power strip except for the sub which is plugged into the same wall plate. My sub/cd/cablebox (the only inputs) do not add any noise when powering on. This is all new starting 2 days ago.

I have an old hk avr325 that i am going to swap it with tonight to see if i still get the hum. Any other advice? Thanks.

 

[lsiberian]

I am using my HK as a pre out which runs to a crown xls2500 to power my mains. With just my crown on I have an almost inaudible hum(I have to put my ear almost touching the tweeter and then it is barely audible). When the HK turns on I get a large increase in this hum, it can be heard 8-10 feet away! Everything is plugged into the same outlet/power strip except for the sub which is plugged into the same wall plate. My sub/cd/cablebox (the only inputs) do not add any noise when powering on. This is all new starting 2 days ago.

I have an old hk avr325 that i am going to swap it with tonight to see if i still get the hum. Any other advice? Thanks.

Have you tried both on with only the dvd an no cablebox on?

If you still have issues.
First plug the sub into the same power strip.

Second let's remove the crown and drive directly from the receiver. See if the problem still exists.

Third try turning hooking the cable box via RCA to the crown and turn them both on(be sure to adjust your gain down.)

 

[jcl]

It sounds like it could be a ground loop. There is some good information on troubleshooting them here :
http://forums.audioholics.com/forums/beginners-audiophytes/5667-ground-loops-eliminating-system-hum-buzz.html

 

[j_garcia]

It sounds like it could be a ground loop. There is some good information on troubleshooting them here :
http://forums.audioholics.com/forums/beginners-audiophytes/5667-ground-loops-eliminating-system-hum-buzz.html

That's what it sounds like to me too. A noise that audible would tend to indicate this, as well as the fact that it happens when the receiver is turned on. Amps don't generally have a lot of noise, however their job is to amplify, and they don't know the difference between good and bad signal.

 

[rnatalli]

Ground Loop is likely, but I have had HK receivers hum for other reasons. If it isn't a ground loop, you can try installing a passive isolator on the FM antenna.

 

[cubazuelen]

So last night I played around for a while and it looks like the noise is from my cable box. I think the receiver may still be acting a little off though. I was getting noise with all my rca connections running but with the cable box and amp unplugged (no power) and just the crown on. Is this odd? Once I disconnected the rca connection from my cable box to the HK the hum disappeared. Keeping the box unplugged is not a big deal since all serious tv/movie watching is done in the theater.

I connected my phone and computer directly to the Crown with no hum so I know it is ok. Tonight I am going to connect the cable box directly to the crown, if the hum reappears I will know its the box, if not though am I correct in assuming there is still an issue with the HK? Thanks!

 

[TLS Guy]

So last night I played around for a while and it looks like the noise is from my cable box. I think the receiver may still be acting a little off though. I was getting noise with all my rca connections running but with the cable box and amp unplugged (no power) and just the crown on. Is this odd? Once I disconnected the rca connection from my cable box to the HK the hum disappeared. Keeping the box unplugged is not a big deal since all serious tv/movie watching is done in the theater.

I connected my phone and computer directly to the Crown with no hum so I know it is ok. Tonight I am going to connect the cable box directly to the crown, if the hum reappears I will know its the box, if not though am I correct in assuming there is still an issue with the HK? Thanks!

The problem is that your cable service is not properly installed. Your house ground and cable ground are at different potentials, and hence the hum.

The cable service should enter within 20 f of the house ground and tied into the house groubnd with stout copper.

 

[j_garcia]

The problem is that your cable service is not properly installed. Your house ground and cable ground are at different potentials, and hence the hum.

The cable service should enter within 20 f of the house ground and tied into the house ground with stout copper.

I had the same issue, and it is quite common. I called the cable company and they eventually corrected the issue for me.