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need help bad w/ hum


leftwinger57

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Hello guys ,hopefully you could sort out my mess of a set -up here.-->2chl Adcomgfa555>Onkyo P-301 pre>InfinitySM112s>Tosiba bdx2200 blu/ray>Sony 5 disc carasel cdp335>Samson 9 outlet plug/surge pro>Shure 240 pro headphones>Toshiba au 37 hdtv>Cablevision source

.I have a Yamaha RX-V665 AVR--->Denon1940ci cdp/dvd --->Klipsch HT500 smalls w/an 8in pwrd sub.---Yamaha YSD11 Dock that's the H/T system and after a while I was not all that impressed w/ it to the point where I clipped the avr on more than a few occassions.Now after talking to some of you forumites and others we all agreed that a indy amp was needed but first I got a pair of Infinity SM112s for real cheap and refoamed on C/L.After hearing these speakers I was totally convinced to go to a 2chl set-up.I looked around and knowing only that I wanted a ss amp that was about 200wpc the Adcom gfa 555 fit the bill and I bought it sight unseen from Audio Classics for $300 w shipping thrown in.Now I did not like the Yamaha as a pre so I bought an Onkyo P-301 which has all the ins/outs that I could ever use.Now I had the 2 sysems set up where they either could play through the Yamaha or if I really want to rock the house go to the Onkyo /Adcom set-up. Mind you I can have both features on both systems and I like it that way .The problem now is lately I'm picking up this god awful hum and this after changing out ICs to Signal Cable models. Where can this hum be coming from ,I did try process of illimination but I just can't seem to get it. I would really like to be able to use both systems but not w/ this hum going on.Please try and think this through w/ me to resolve this issue.I did have the best of both worlds were the dock was playing w/ the 2-chl and my 5 disc player was doingthe same. I hope I explained this to the fullest and since I'm no genuis maybe a detailed drawing would help......

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Relax. Slow Dowwwwwwwwwnnnnnnnn.

Disconnect everything, including the AC power cables.

Connect the power amp to AC power. Connect the speakers to the power amp. It should be quiet. If not, the power amp has a problem.

Work your way back to the sources (CD, DVD, set-top box, turntable (remember those?), connecting one component at a time. At some point the hum will raise its' ugly head. Lets us know what was connected when it was quiet, and what was added when the hum occurred and we'll sort it out. Let us know which components have 3-pin AC plugs.

I suspect it has something to do with running the H/T system AND a 2-channel set-up at the same time.

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Good advise Greg. This is the right approach.

To the OP, a big word of caution, make sure the speakers are off line or completely power down the amp(s) before you start pluging in new components. Don't hook up or unhook anything hot, especially with the speakers on.

Could be disaster, no short cuts here!

Does it sound like I have done this before? Yep!

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Hey guys,I listened intently to your advice,firstly I waited for daylight to work on this thing.I pulled the rack out and powered everything down.As a added little help for future teardown I labeled everything. So here's where I stand ,the Yamaha ,tv ,cdp and dock all work as they should.I tried a regular dvd and that worked fine also.Now comes the trouble ,I turn off my Yamaha just so I get no interference between the 2 systems and when I put on the Adcom then the Onkyo pre I get the hum .I do know where's it's coming from but I really do not know how to resolve this. When I remove the HDMI OUT of the yamaha that goes to the tv the hum is gone. I put the cord back and back comes the hum.I doubt it's a beat cord so I could use some ideas here.

Another bit of my wackyness is that I like watching silent t.v. w/ tunes going at the same time and it works all the time w/ the toslink optical.

so all devices are working but the cord/hum is still there. And yes I know I get nutty and carried away but I took all the time and care I could muster.

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Now is the time to sketch the equipment interconnections for us. One rectangle for each piece of equipment, one line for each cable. Label each cable with its' signal (e.g., L audio analog, SPDIF, HDMI) and an arrow to indicate signal direction. No need to label inputs and outputs of the equipment. No need to include TOSLINK cables in the sketch. Don't draw the AC power cables. Just put an "AC2" next to anything with a 2-wire AC plug and an "AC3" next to anything with a 3-wire AC plug.

Another bit of my wackyness is that I like watching silent t.v. w/ tunes going at the same time...

Nothing wacky there, we did that in the 60's.

...and it works all the time w/ the toslink optical.

Nice thing about optical, no ground connection. But at the expense of more jitter.

And yes I know I get nutty and carried away but I took all the time and care I could muster.

This is a grounding problem. Grounding discussions between grown men have been known to break out in fist fights. Grounding problems have sent some very experienced audio professionals chasing their tails for days. You're doing fine.

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