I have three HT amps; B&K 700.2, Fosgate Audionics 5002 and a Cinepro 3k6 Pro.
I know I have noisey AC but the B&K 7-ch amp shows no sign of AC ground effect while my Cinepro and Fosgate both do... to an extreme degree. With those two amps plugged in, I get a significant humm through my subs and speakers.
Tried to isolate the problem with both and had no success. So now I'm condsidering buying an isolation transformer to clean up the AC and get the same performance as the B&K for all three amps.
AC conditioners I've seen are the Monster Power AC Regenerator, Richard Gray's high-quality (and pricey) subStation, or something most subtle like Tripp Lite IS250 250W Isolation Transformer, B+K Precision Isolation Transformer BK TR-110 ISOPACK, or Toroid Medical Grade Isolation Transformer ISB-030A. All of these look to be quality, can I achieve my goal without spending too much $$$.
Last edited by AudioLib; 12-19-2011 at 08:19 PM.
This sounds like a ground loop rather than anything having to do with noise on the AC line, in which case an AC line conditioner is unlikely to do you any good. You most likely will need isolators in the audio lines, e.g., http://www.jensen-transformers.com/iso_aud.html.
Definitely a ground loop prob. Still don't understand why my B&K is invulnerable to it.
Guess I'm not clear on why a AC line conditioner won't solve the problem?
Just a Best Buy. The death of Tweeter Etc. made them to only local AV supplier of note. Pretty sure they won't let me walk out with isolation unit.
By the by, my wife worked for Russound and I was able to take the Fosgate to their lab for a test and it was dead silent through an isolation xformer. Maybe I should see if I could borrow that over a weekend to try at home? Hmmmm...
Magnepan, B&K, Emotiva, HSU
Are they all plugged into the same outlet/circuit? (guessing not)
Can't hurt to go buy one of those little LED circuit wiring checkers to be sure they are wired correctly, and that the ground is wired.
Also, if they are plugged into power strips try and bypass them.
Also, see what else is on the circuits you have them plugged into and unplug other devices from the circuit to see if you have anything going on with them.
Ground loops usually come from having your sources/amps on different circuits though, and sometimes there's no way around that.
I'm currently targeting a Panamax 5500 which appears to be a AC regen unit of note that could isolate my Cinepro.
1) Balanced connections to the power amps, if feasible.
2) A ground isolator designed specifically for cable or satellite receivers between the cable or dish feed and the input on the box. (Such isolators have to be designed with extended high-frequency bandwidth so as not to block part of the signal.) Cable and satellite boxes are very common causes of ground loops, at least when there's any sort of RCA connection to the rest of the system.
3) Isolation transformers in the signal lines to the power-amplifier inputs.
You may find other useful advice on the Web. If you are going to get the power conditioner anyway, you might as well give it a shot before doing anything else, but I'd be surprised if it were to help with this particular problem. Here's a link to the most useful and authoritative tutorial on ground-loop elimination I know of: http://www.jensen-transformers.com/a...%20seminar.pdf; see especially section 5.4.
I live out in the Metropolis of East Bend NC. I would go to the local hardware store $14.95 for a 6' grounding rod. Find out line isn't giving you problems, run the line out to a small breaker box, ground it out there and it's a pain and requires a bit o work, but worked great for this old hick. Best of luck buddy...
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