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One more question. Does the sub hum with input cabling disconnected? I know that this is simplistic and I'm sure that you've done this, but I have to ask. When tracing down hums, I always start with the just the sub amp hooked to the wall - no input cabling. Then I would hook it up to the receiver with all of the receiver inputs unplugged, plug one set of component cables into the receiver at a time with the component turned on and see if you can't isolated the problem that way. I would imagine that you have already done this. Another thing to consider is the unseen hum inducers, like in-wall wiring in proximity and in parallel to any signal wiring or to the plate amp in the sub. I've seen this happen all too frequently. You may want to pop the top off of the Denon and see if it is properly grounded internally. In other words, make sure that the chassis ground and the neutral are common. Same with the plate amp.Concerning the sub amp being on the same phase as the 'fridge: First, make sure that all of the above is OK. Then you have to ask yourself some questions. What are the trade-offs involved in the opposite phase going to be? Plug the subamp into Phase 1 and listen to determine if it is superior in sound that way. Since electricians spend time balancing current demands in the panel there is going to be downside/upside considerations both ways. Generally speaking audio should ALWAYS be on the same phase.As a diagnostic tool, destroy a 3-prong adapter by removing the ground pin and file the left hand (wide = neutral) blade until it is the same width as the right hand one. Check each piece of gear by using this plug to try input AC polarity both wys to that piece of gear. Odds are you will find one offending piece and then we can figure out how to do this properly. DON"T USE THAT PLUG UNDER NORMAL USE! Dave
Dave,One of the downsides about posts is you can’t provide enough details without writing a darn book. If you try not to hog (or derail) the thread, then you leave out pertinent stuff.Anyways, back many months ago when I was trouble-shooting servo sub hum, I did try different scenarios to pinpoint problem as much as possible. I did disconnect rca single cable from avr, & hum persisted. I did try different outlets, move sub to other room/ different circuit & hum persisted. I unplugged all A/V equipment & hum persisted. I tried different cables & well, you get the picture.So I assumed that eliminated everything except for servo sub internals and/or residential wiring. Fast forward to the here & now, & your comments re: noise sources & proper phase layout caused me to revisit my existing problem for possible fix. Not sure if I’m any closer to resolving issues, but I’m learning a heckuva lot in the process. Thanks !
Dave, It's a 3 prong @ the amp. I used a cheater plug on the outlet end w/ no change. I did talk to Brian Ding @ Rythmik & he said they have never had problems reported like mine for the A300SE amp. Can't remember if I discussed w/ Danny or not.Werd, I've checked the driver/ amp connections before when I put in No-Rez, but I need to inspect things again.I don't want to monopolize the thread any further. At worst the hum is just barely heard from 5' away when all is dead quiet. Shoot, when the fridge kicks on from 15' away it drowns it out. I'll delve into the sub guts when I feel a little more frisky.
Just saw this thread and read it. I will have to jump in here as there has been mentioned several times about "phase" coming from the breaker box.It is true, that homes have 2 120 volt lines and a neutral coming in from a branch transformer from the wonderful utilities, however, the use of the term phase may be misleading. Both 120 volt lines are IN PHASE with each other. That is how we get 240 volt, by putting these 2 branch circuits in series.Since the power comes from a single transformer, the 2 lines are "connected" as well as the neutral, relative to each other, so trying to isolate the noise from one set of 120 to the other is pretty much futile. A voltage surge, such as one the may come from a capacitor started furnace motor, may end up in both branch circuits.The best was to determine if there is an offending appliance, is to shut off every breaker in the house, except for the main, and the circuit your system is on. If the hum is there right away, it's in your system. If it's not, began to turn each breaker back on, one at a time and check to hum with each new additional breaker activation.Wayner