Outlaw 1050 + Parasound HCA-855A (1 Viewer)

[Chris Demaree]

I just purchased a Parasound HCA-855A (5 channels, 85wpc). After connecting it to the pre-outs on my 1050, calibrating sound levels, listening to 3 CD's and watching a movie I noticed a few things. The sound from my speakers (Paradigm Titans, cc-170 and Energy Take2's) is definately 'better'. It seems to have more impact and a bit more clarity. The one downside is a very slight hum that might be comming from the amp (if I turn off the 1050 and leave the amp on - the hum is still there). Since I have each amp channel set to 'maximum' would it make any difference if I turned them down slightly and just increased the volume on my 1050 to compensate? Generally speaking, should the amp channels be set to maximum or just a bit under prior to calibration?

 

[Steve Daniels]

Since I have each amp channel set to 'maximum' would it make any difference if I turned them down slightly and just increased the volume on my 1050 to compensate? Generally speaking, should the amp channels be set to maximum or just a bit under prior to calibration?

Probably not, but it wouldn't hurt to try it.
Here's the 855A owner's manual, in case you haven't seen it already. Parasound recommends setting all of the level pots to max unless your pre-amp (in your case receiver) has too much gain, or you're using the amp in a bi-amp installation (which you're not).
When you say that the hum sound is coming from the amp, you are talking about the amp, and not the speakers, right? If the hum isn't coming through the speakers, you have a mechanical hum in your amplifier's transformer.

 

[Chris Demaree]

The hum is comming through the speakers, from the amp. Since I have no prior experience with external amps, I was wondering what the causes might be. It doesn't bother me, or interfere with music/movies, but I am curious

 

[Steve Daniels]

You are describing a ground loop hum.

From Crown's Amp FAQ:
Sixty(60)-hertz hum (fifty(50) hertz internationally) is a result of having a ground loop in the audio system. This is where there are two or more ground references in the system, and current is flowing from one ground point to another. Any piece audio equipment requires one ground reference. Ground loops can be formed in a number of ways. For example: An audio power amplifier obtains its ground from the AC power cord. The mixer, which drives the power amplifier, also receives its ground from the AC power cord. When the audio cable connects the mixer to the power amplifier the amplifier now sees a second ground from the mixer. If the mixer and power amplifier are both plugged into the same AC power strip then the mixer/amplifier interconnect cable shield can be cut to eliminate this problem. On most Crown amplifiers there is a "ground lift" switch on the back of the amplifier that performs this function and can be used to eliminate hum caused by ground loops. If you are using a cable service, such as cable TV, and you are routing the audio through your stereo system, you may experience a ground loop hum. This is a result of the cable company's ground reference setting different than your system ground reference. You can contact your cable company and get an isolation transformer that will take care of the problem.
Another cause of system "hum" is electrically induced, such as having a very sensitive component too close to a power transformer. Power amplifiers have large power transformers and can induce a magnetic field into other equipment. If you suspect this may be the cause of your problem then placing more distance between the two components is the only practical solution.
Excessive "noise" on the AC mains can cause "buzz" in certain components. Lighting dimmer packs are notorious for inducing noise onto the AC mains. If this is your problem try putting the lighting system on a different AC mains feed.

Here's a decent google search that might help you out, too. Especially anything mentioning cheater plugs. E.g., this one.

 

[Chris Demaree]

Thanks for information Reading through the information has given me a couple of ideas.