HUM at 60hz and NanoAvr-DL - Home Theater Forum and Systems - HomeTheaterShack.com

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post #1 of 10 Old 07-11-16, 08:41 AM Thread Starter
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HUM at 60hz and NanoAvr-DL

I start this thread only to share my experience so it could help someone somewhere.

My HT system is completly silence with no ground loop problem and that since the begin and what ever gears I have in the chain. My system is always completly silent.No hum at all.

But, this week-end, I discovered that putting the NanoAvr-DL unit into the chain created a hum. When I put on the NanoAvr-DL and put on the bd-player= humm!!

I spent many hours this week-end on Internet and on my system to find the source.

Finally, I found the source: cable of the cable TV !!.. When the cable is connected, even if the step-top box (cable decoder) is off = humm. Disconnect the cable= no humm!
It is a 60hz humm.
I followed the advises of a technician in a forum. . First, don't call the cable company, they will not know what you are talking about. !! Second: you must go OUTSIDE of your house, find where the cable is splitted for the FIRST TIME by a splitter and BEFORE the splitter make a correct ground path with a wire connected properly to the mass, ideally connected to the rod stick in the ground. Voilà.
My system returned to be quite as before.

And, BTW, I saved 70bucks not buying any ground loop eliminator, transformer or any gizmos of some sort !

Now two questions.

Was the hum there before NanoAVR-DL (when I did not hear it) or is it created by this device?

Does the cable-tv hum influence the measures with REW even when I do not hear it?
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post #2 of 10 Old 07-11-16, 02:58 PM
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Hum fields are always there, sometimes the configuration of your system grounds and shields is such that those fields are allowed to generate 60 Hz noise in the system. There is no one piece generating hum, but one piece that completes a circuit that allows it to become a disruptive factor. You did well diagnosing the cause and interrupting it without bandaids, which work too, but can get expensiive
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post #3 of 10 Old 07-11-16, 03:07 PM
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At LF, there is usually a bunch of noise that you can't hear directly. LF noise is not as audible, but can mess up a soundstage.
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post #4 of 10 Old 07-12-16, 05:40 AM
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Re: HUM at 60hz and NanoAvr-DL

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Does the cable-tv hum influence the measures with REW even when I do not hear it?
Didn't really answer your question before. If the hum is present in your system, as it was BEFORE you executed your ground fix, then you would be able to measure it with REW, and probably hear it too. Depends on the level, LF stuff is harder to hear directly but can make a mess of soundstage & imaging. A quick test: increase your AVR volume to 10 dB above your normal listening level. If you hear ANY noise from your speaker while still sitting at the LP, then you need to fix it, it is messing up your sound. You might not realize it, but when you have eliminated that noise, then you will hear the improvement. With that +10 setting, if you can only hear noise from the speaker when you stand up and put your ear up close, like right up to the tweeter, then most likely your are OK.
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post #5 of 10 Old 07-12-16, 08:43 AM Thread Starter
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Re: HUM at 60hz and NanoAvr-DL

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Didn't really answer your question before. (...)
But now you did ! Thank you again.

Quote:
LF stuff is harder to hear directly but can make a mess of soundstage & imaging.
Since many months I have a right side shift in the sound stage that I could not explained only with the dissymmetry of my fronts placement in my room (left open narrow corridor and right with a side wall).

Quote:
You might not realize it, but when you have eliminated that noise, then you will hear the improvement. With that +10 setting, if you can only hear noise from the speaker when you stand up and put your ear up close, like right up to the tweeter, then most likely your are OK.
I think I will be able to confirm after more listening session. But, since last Sunday I can tell that sound stage has changed probably for the best. Hopefully my brain is not tricking me!
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post #6 of 10 Old 07-12-16, 02:23 PM
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Re: HUM at 60hz and NanoAvr-DL

Thank you for sharing, FargateOne! It's always refreshing to learn through volunteered information. My kinda style, too, where you don't have to sift through pages of posts for the answers you need! And thank you too, Wayne, for your insights into low-level noise.

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post #7 of 10 Old 07-12-16, 05:51 PM Thread Starter
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Re: HUM at 60hz and NanoAvr-DL

My pleasure.
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post #8 of 10 Old 07-13-16, 08:01 AM Thread Starter
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Re: HUM at 60hz and NanoAvr-DL

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AudiocRaver wrote: View Post
(...) A quick test: increase your AVR volume to 10 dB above your normal listening level. If you hear ANY noise from your speaker while still sitting at the LP, then you need to fix it, it is messing up your sound. (...) With that +10 setting, if you can only hear noise from the speaker when you stand up and put your ear up close, like right up to the tweeter, then most likely your are OK.
I did the test yesterday. Usually the main volume of the receiver is at 68-69 (= 69-70 with the SPL meter). AT this volume everything is quiet. I raised the main volume at 77. At LP I still hear a faint hum. If I disconnect the cable again= silence.


Maybe the signal is not completly eliminated but the step-top (cable decoder) is the culprit. If I diconnect the hdmi cable between the cable decoder and CXU= no humm; also if I disconnect the decoder from the wall outlet.

Last edited by FargateOne; 07-15-16 at 07:47 AM.
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post #9 of 10 Old 07-19-16, 10:27 PM Thread Starter
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Re: HUM at 60hz and NanoAvr-DL

And, now on HUM,

thank you again Wayne and Lumen. I continued my research to finally discored that the culprit was a bad hdmi cable. I had one of a different supplyer than the others.
I connect the set-top box and the bd-player and = hum disappered at 95%. I did also what a cable service technician suggested to me today: connect any coaxial cable between your set-top box and your receiver or bd-player to equalize the potential between them. I did it too= hum disappered at 100% in the mid drivers ( so 60hz killed !), remaining a very faint hiss in the tweeters not audible at LP with the main volum at 80db!

And Wayne, you know what : this hum was messing the sound stage image and the sound of every channels!!

Do you think that a new round of measurements is required ?
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post #10 of 10 Old 07-20-16, 04:12 AM
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Re: HUM at 60hz and NanoAvr-DL

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FargateOne wrote: View Post
And, now on HUM,

thank you again Wayne and Lumen. I continued my research to finally discored that the culprit was a bad hdmi cable. I had one of a different supplyer than the others.
I connect the set-top box and the bd-player and = hum disappered at 95%. I did also what a cable service technician suggested to me today: connect any coaxial cable between your set-top box and your receiver or bd-player to equalize the potential between them. I did it too= hum disappered at 100% in the mid drivers ( so 60hz killed !), remaining a very faint hiss in the tweeters not audible at LP with the main volum at 80db!

And Wayne, you know what : this hum was messing the sound stage image and the sound of every channels!!

Do you think that a new round of measurements is required ?
I do not think so. I do not believe that hum at that low level would affect the calculation of filters in Dirac Live.

Good detective work! Now you can really enjoy that system!
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