Originally Posted by atx2014
already called parasound and talked with two guys at different times. both think it's "normal" not a defect on the amp, and i don't need to do/fix anything. but no one here thinks the same. just curious, are your hums caused by DC offset audible from listening positions? or just audible within 3 feet as in my case? thanks
Same issue and same response from Parasound here i.e. I've tried everything to resolve and could just be an unlucky combination of factors in my home/setup, best thing is to send back Halo units to dealer or sell (currently going down this route but reluctantly so).
Recently upgraded from a Anthem MRX 500 and Parasound Halo A52 to Anthem AVM 60 and Halo A51 + 3 x Halo A23's. Excellent sound when playing music / movies and beautiful, well built equipment, but audible hum from ~6ft away and loud when next to speakers coming from all channels in an 11 ch atmos system. Spoke to Parasound twice, Torus power same number of times (very helpful but potential solution comes down to $3200 - $4999 high end isolation transformer and not a guarantee to resolve), much internet research esp. Bill Whitlock @ Jensen Transformers and many calls / IM's to electrical engineer friend. Many calls to dealer also to try various combinations to isolate. No definitive root cause can be isolated.
Hum from any speaker (even tried loaner from different brand from local store to isolate HT speakers) regardless of input or no input, balanced XLR makes no difference, grounding rack, grounding individual non-grounded component like Anthem, ground lifts on Halo's makes no difference, ran extension cable to different room/circuit. Still get hum. It's basically like a curse.
The only improvement is for me to eliminate large toroidal transformer and use Class D or non A/AB amp i.e. Emotiva XPA Gen 3 (temporary Amazon purchase) eliminates and reduces hum to very low level which I'd be ok to call acceptable. Not really excited about not being able to use Class A/AB.
Could be a power line issue, doubt its ground fault at this point as verified grounding connections, had an electrician double check wiring and my own multi-meter measurements and house wiring seems ok (home only 5 years old and custom build + generally high standard workmanship & components).
Going to try a DC offset eliminator this weekend also, but reluctant to spend thousands on isolation transformer unless really, really necessary - problem is to find out I have to buy one and if it doesn't work, the experiment costs return shipping by freight and 15% restocking fee (fair terms but expensive for me given I've already spent $200 for an electrician to tell me everything looks good, nothing unusual going on). Also going to move some breakers around in breaker box esp. for 2 main circuits in theater room and put on same leg to eliminate issues resulting from potential asymmetrical AC/"DC offset" between the circuits.
Its a real head scratcher this one.