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Onkyo 605–Tracking down the hum

post #1 of 13
Thread Starter 
Before I begin I would like to point out that I've the other threads about the Onkyo 605 speaker humming over the HDMI connection. For my system I believe I tracked down the problem (which may or may not be different than the others, hence the new thread) but I'm not sure what solution route to go.

The following is how my receiver is setup:
Comcast DVR box (HDMI in)
TV (HDMI out)
Xbox 360 (Component + digital optical)
Xbox (Component + RCA stereo)
Also only have front L+R speakers hooked up right now (not in bi-amp mode)

Now the humming can be heard on all components. That includes when the system is being fed bitstream and PCM (tested with the Xbox 360). You can't hear the hum as much with PCM but it's over the top with bitstream. This is around volume level 55.

So I did the typical systematic approach of removing each component and adding them back until I hear the hum. The DVR was the first thing I hooked up to the receiver and that's what kicked off the hum. Out of curiosity and based on previous threads I removed the coax cable from the DVR and the humming noise stopped. I hooked everything back up to the receiver (minus the coax) and no humming on any setting or input. As soon as I touch the coax cable back to the DVR box (at any contact point including the screws) the hum is back. So now I've found the cause, the problem is the solution. Also out of curiosity I tried to ground the coax cable with a lead from a volt meter to the ground of an outlet (in retrospect probably not the smartest thing to do). I placed the one end of the lead on the coax cable splitter (IN: coax from wall, OUT: cable modem, DVR) and the humming noise was reduced but still able to be heard.

I haven't tried any of these as of yet as they would cost extra cash at this point so I wanted to get some advice. The following are what I'm considering
Running copper wire in some kind of fashion between the DVR and Onkyo to ground them both. I'm not sure how to properly do this
Invest in a isolation/matching transformer to put in line with the coax after the splitter and before the DVR. Problem with this is I've seen claims that these devices will screw up digital cable quality
And lastly return the 605 for another and hope it was just a defective unit.

So any thoughts?

Thanks in advance
post #2 of 13
Anyone have any input to this? I'm having the exact same problem with my 605.
post #3 of 13
Thread Starter 
I'm also considering another soultion. Run the HDMI straight into my TV avoiding the 605 (which is kinda against why I bought the product in the first place) and run a digital optical cable from the cable box to the 605. I'm assuming the digital optical cable won't conduct the hum since it's technially just light and glass.
post #4 of 13
Ding ding, ding ding!

We have the infamous cable box.

Now guess what ? The ground connector on that one is connected to miles of copperwire shielding crisscrossing your hood.

What you need is remove those miles by inserting a Jensen or similar ground loop isolator in the cable entering your box and Voila !

Give it a try, this was the cause of problems in two homes with 3 different brands of receivers in my homes.

And get a used Dish system on the eeecky bay and some crimp tools, read up on www.satelliteguys.us and set up a 50 channel HD system.
post #5 of 13
Another vote for one of these. Jensen VRD-1FF.



Try Fleabay for deals.
post #6 of 13
Quote:
Originally Posted by Hopstretch View Post

Another vote for one of these. Jensen VRD-1FF.



Try Fleabay for deals.

will this thing impede high def tv signals???
post #7 of 13
Quote:
Originally Posted by jxo View Post

will this thing impede high def tv signals???

Ditto on this question. I wouldn't expect it to affect anything, but if possible I'd like to be forewarned.
post #8 of 13
I help a fair amount of people with their hum problems. Before I show up? They are convinced they did everything needed to make sure it wasn't the cable, dish, direct feeds... So far? better than 99.99% of the time, it is indeed their cable / dish / direct feeds.

They seem totally shocked when I go disconnect the coax and the hum goes away even though this is what I told them before I came over.
post #9 of 13
Quote:
Originally Posted by deecee20 View Post

Ditto on this question. I wouldn't expect it to affect anything, but if possible I'd like to be forewarned.

I have one on each of my Motorola DCT-6416 PVR boxes and they work just fine. Without them the hum is enough to make your teeth rattle.
post #10 of 13
Quote:
Originally Posted by strange_brew View Post

I have one on each of my Motorola DCT-6416 PVR boxes and they work just fine. Without them the hum is enough to make your teeth rattle.

where is the best place in cable system to insert this baby?

I assume the best place to install it is where the cable comes into the house.

in addition to the HD question, could this device impede internet signals?
post #11 of 13
im having a problem as well...so let me get this straight....the DVR coax cable is the cause of the hum on ALL the components???

wow thats crazy

im going to look into those ground loop isolator thingies
post #12 of 13
Yes I just starting hearing the "hum" from my sub.. Unplugged the coax from the cable box.. poof hum gone.. So one of those isolators will work?
post #13 of 13
Hey, Unplugged coax from Digital Cable box and..........the humm is gone. Off to E-Bay. Thanks to all who posted. Now I can move on to just relaxing and enjoying my new 605 and my Infinity speakers. They are great. Thanks again Mike
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