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#274120 - 2018-03-11 22:30 G65 generates noise in surround speakers
Registered: 2007-09-17
Posts: 30
Snooky Offline
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Snooky Offline
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Registered: 2007-09-17
Posts: 30
Replaced my trusted G68XV with a new G65 a while back. Shortly thereafter I started remodeling my listening room, which took longer than expected (usually does). But now I'm back up and running. First thing I noticed was a distinct electronic hum in my rear surround speakers. Not loud, but audible. Can't say for sure if this has been the case with the G65 from the start.

First I thought it was faulty cables, interference somewhere in the chain or something wrong with the fairly cheap power amp I use for the surround speakers. But through the process of elimination I'm certain that the G65 is the source of the problems. I've tried different cables, swapped power amp between surround and mains and tested with a Hegel H20 DAC instead of the G65. The noise will only disappear when I disconnect the XLRs going from the G65 to my surround amp, or when I use the H20 instead of the G65.

I also noticed that the G65 can alter the noise emitted depending on the processing it does. When I set the G65 to stereo (ore any DSP mode that doesn't utilize surround speakers) the noise is almost flat. A fairly even but weak permanent beep at about 8k Hz. If I change to a multi channel source the sound changes from even to a series of short beeps at a few different tone levels for 1-2 seconds, before the surround speakers starts playing what they're supposed too and the noise returns to be the same as in stereo mode. It doesn't seem to change when I adjust the volume. And the rear channels are the only ones emitting the noise.

Any one got some idea of what I should try next?

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#274123 - 2018-03-11 23:32 Re: G65 generates noise in surround speakers [Re: Snooky]
Registered: 2009-11-10
Posts: 1,335
CMB Integrations - Bruce Offline
Meridian Partner Working on the ultimate question
CMB Integrations - Bruce Offline
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Registered: 2009-11-10
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Loc: Lexington, South Carolina, USA
Can't tell from your signature what the rest of your equipment and sources are. Do you have cable tv? If so try disconnecting the cable tv cable going to the cable box. If the hum goes away, get a Jesen ISO MAX RF isolation tranformer.


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#274126 - 2018-03-12 06:36 Re: G65 generates noise in surround speakers [Re: CMB Integrations - Bruce]
Registered: 2007-09-17
Posts: 30
Snooky Offline
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Snooky Offline
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Registered: 2007-09-17
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Good suggestion. Unfortunately the noise is there when no sources are connected to the G65.

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#274186 - 2018-03-13 19:31 Re: G65 generates noise in surround speakers [Re: Snooky]
Registered: 2007-09-17
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Snooky Offline
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Snooky Offline
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Registered: 2007-09-17
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Turns out this was not completely true. I forgot to disconnect the network cable running to my HD621. Missed it back there. Will try without it later to see if this is the source of my trouble.

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#274216 - 2018-03-14 16:43 Re: G65 generates noise in surround speakers [Re: Snooky]
Registered: 2007-09-17
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Snooky Offline
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Nope. Made no difference.

Fun observation. When I use the remote to adjust volume on the G65 the humming noise goes from flat to short beeps. Doesn't get louder, it just breaks up to a pulse which is exactly in sync with the changing numbers indicating volume on the G65 front panel.

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#274218 - 2018-03-14 19:49 Re: G65 generates noise in surround speakers [Re: Snooky]
Registered: 2000-05-28
Posts: 8,659
Fiddler Offline
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Fiddler Offline
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Registered: 2000-05-28
Posts: 8,659
Loc: Northeastern, USA
You still have not described the rest of your system.

Since you had a G68X and went to a G65 my guess is you're running Analog. Analog setups are more prone to hum than DSP setups.

I'd try swapping channels around to narrow down the source. Could be just a bad amp.

Also these "DC Blockers" do work in some instances.

Similar to this https://www.amazon.com/gp/product/B008O37LXY


- Fiddler (IMHO)

If you think listening to music is fun, try learning an instrument.
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#274222 - 2018-03-15 00:20 Re: G65 generates noise in surround speakers [Re: Fiddler]
Registered: 2007-09-17
Posts: 30
Snooky Offline
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Registered: 2007-09-17
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Oh.. Sorry. I'm running all analog here, so you guessed right. 7.1 system with Martin Logan front row, and Klipsch surrounds. Velodyne sub.Burmester037 power amp for the front, and Parasound A51 for the rest. XLR to all channels. Only two inputs in use atm. Optical from my TV,since the HD621 has no ACR, and a good shielded cat6 network cable from the HD621 to the G65.

PC, Shield, xbox and bd player all connected to the HD621 with HDMI.

G65, power amps and HD621 are powered through an IsoTek Aquarius AC "purifyer".

Since the hum wasn't there when i used my G68xxv, I'm pretty sure the G65 is the culprit here. I'm not sure if a flaw in the processor makes It create that noise, or if it's just more sensitive to an outside disturbance than the 68 was.

Last thing to check is power connections i'll give that a try later.

Edited by Snooky; 2018-03-15 06:17.
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#274227 - 2018-03-15 09:35 Re: G65 generates noise in surround speakers [Re: Snooky]
Registered: 2001-05-23
Posts: 2,718
Gianni Offline
Great Green Arkleseizure
Gianni Offline
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Registered: 2001-05-23
Posts: 2,718
Loc: North London, United Kingdom
Originally Posted By Snooky
G65, power amps and HD621 are powered through an IsoTek Aquarius AC "purifyer".
I would be inclined to eliminate the IsoTek by unplugging the various components and by trying the components plugged directly into wall sockets.

Not suggesting that the IsoTek is doing anything wrong but it is a variable that should be eliminated.

Where are you based for further intel on what your electrical system is like?


Wonderful perfect quadraphonic sound with distortion levels so low as to make a brave man weep smile
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#274247 - 2018-03-15 16:41 Re: G65 generates noise in surround speakers [Re: Gianni]
Registered: 2007-09-17
Posts: 30
Snooky Offline
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Snooky Offline
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Registered: 2007-09-17
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Agreed. Tried without the IsoTek. With no other components than the G65 and the surround power amp plugged directly into the same wall outlet I still get humming. Using the Burmester instead of the Parasound to power the rear channels significantly reduces the noise, but it's still there.

I live in Norway, and my huse is hooked up to an IT electrical system.

I'm still convinced that this is related to noise from the electric mains, which for some reason only becomes audible through the G65 and only in the rear surround channels.

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#274249 - 2018-03-15 16:51 Re: G65 generates noise in surround speakers [Re: Snooky]
Registered: 2001-05-23
Posts: 2,718
Gianni Offline
Great Green Arkleseizure
Gianni Offline
Great Green Arkleseizure

Registered: 2001-05-23
Posts: 2,718
Loc: North London, United Kingdom
Originally Posted By Snooky
I live in Norway, and my house is hooked up to an IT electrical system.
That means you are running a European voltage/frequency at 230v/50Hz which helps to know.

What is an "IT electrical system"?

Are there any other devices plugged into the electrical system? I once had a 562V that, even when switched off, would pick up and transmit hum from a fridge in another room into the system - most audibly at the rear because that was closest to my ears.


Wonderful perfect quadraphonic sound with distortion levels so low as to make a brave man weep smile
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#274254 - 2018-03-15 18:29 Re: G65 generates noise in surround speakers [Re: Gianni]
Registered: 2007-09-17
Posts: 30
Snooky Offline
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Snooky Offline
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Registered: 2007-09-17
Posts: 30
Originally Posted By Gianni
What is an "IT electrical system"?

Are there any other devices plugged into the electrical system? I once had a 562V that, even when switched off, would pick up and transmit hum from a fridge in another room into the system - most audibly at the rear because that was closest to my ears.
IT system as opposed to TN or TT. Not ideal for hifi because of poor earthing, but more reliable in the sence that it won't blow fuses at unstable currents. Better explained here .

I agree. There is something somewhere in the house which is creating a disturbance that only the G65 pic up. And the IsoTek has no effect, so that was probably just a waste of $$.
The hunt continues...

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#274256 - 2018-03-15 21:34 Re: G65 generates noise in surround speakers [Re: Snooky]
Registered: 2007-09-17
Posts: 30
Snooky Offline
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Snooky Offline
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Registered: 2007-09-17
Posts: 30
Finally found the culprit. A fairly new Samsung LED TV in a different room on the same floor. When I unplug its unearthed power cable my rear speakers stop humming immidiately. Plug it in and the noise returns. Reversing the cable has no effect. A ground loop is out of the question since the TV is not connected to anything except internet over wifi.

Still think it's strange that the G65 is the only unit that picks up this interference. My old G68 and the Hegel I tried was unaffected. But still it's obvious that the TV generates RFI on the power lines, and must be dealt with. The so called filter from IsoTek makes no difference what so ever. Seems pointless. Seriously doubt other "hifi" power filters will do better.

Suppose I could get a dedicated mains line just for my gear. But this problem could just as easily have it's source in a component which is a part of that setup, and a dedicated line for each component isn't realistic.

Aside from selling the TV, what would be a sensible solution? Perhaps an industrial RFI filter, or an online ups?,

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