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Re: Grounding and hum
alan #264671 06/26/09 04:04 PM
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Alan, I always thought it wasn't at all unusual to have some residual noise when listening up close to a speaker and having the volume up to "listening levels"?


::::::: No disrespect to Axiom, but my favorite woofer is my yellow lab :::::::
Re: Grounding and hum
MarkSJohnson #264680 06/26/09 05:07 PM
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My system is dead silent at listening levels with nothing palying and the system powered up.


Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70
Re: Grounding and hum
MarkSJohnson #264682 06/26/09 05:12 PM
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My EP500 Sub arrived yesterday, which was good timing because I only just finished installing the QS8s that had arrived with the rest of my Epic 80 system on Monday.

Anyway, I switched on the system last night for the first time with everything connected (which was previously working just fine with only the fronts and center speakers) only to find very loud mains hum coming from all the speakers!!!!

Luckily, I had actually read the sub woofer manual before setting it up, so rather than spending hours isolating the problem, I just removed the Chassis Grounding screw, as instructed, from the sub and that solved the problem!!!

It was funny, I was holding onto the screw when we powered the system up again, and both my wife and I had absolutely no confidence that this would solve the problem.

Re: Grounding and hum
jakewash #264725 06/27/09 12:02 PM
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 Originally Posted By: jakewash
My system is dead silent at listening levels with nothing palying and the system powered up.

I'm out of state at the moment, but have to check out my system when I'm home again...


::::::: No disrespect to Axiom, but my favorite woofer is my yellow lab :::::::
Re: Grounding and hum
MarkSJohnson #264742 06/27/09 05:27 PM
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Hi Mark,

With older vintage solid-state gear ('60s and '70s), you'll definitely hear some thermal hiss (not hum) when the volume control is well advanced and your ear is close to the speakers.

You'll also normally hear some thermal hiss on AV receivers on the Phono input (moving-magnet--MM), which adds another gain stage, especially so on a unit that has a moving-coil (MC) cartridge input. The latter adds yet another stage of gain, so unless it's a really expensive low-noise design, you'll almost always have a bit of residual hiss on the MC phono input.

Modern inexpensive stereo or AV receivers may have a bit of thermal hiss when the volume control is near maximum, but you shouldn't have any hum if all the grounding is correct.

Well-designed separates (separate preamp and power amp) should be virtually dead quiet, even at maximum rotation of the volume control and when you're really close to the speakers.

Regards,
Alan


Alan Lofft,
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Re: Grounding and hum
alan #264743 06/27/09 06:06 PM
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 Originally Posted By: alan
Well-designed separates (separate preamp and power amp) should be virtually dead quiet, even at maximum rotation of the volume control and when you're really close to the speakers.

I assume this is without music going through? Otherwise it would become deaf quiet... ;\)


E = MC2 = ((2M80 + VP180 + 4QS8)/(EP800 + EP500))^(ADA1500 x D2v)
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Re: Grounding and hum
EFalardeau #264745 06/27/09 07:40 PM
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Exactly! ha, ha.


Alan Lofft,
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Re: Grounding and hum
alan #264746 06/27/09 08:11 PM
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I would bet the majority of people with ht systems deal with ground loops, interference or other related problems at one point or another. Ground loops seem very common to me (that is atleast my impression). I had to deal with it after adding a second sub. The hum was coming through the subwoofer and not the speakers.

Also at one point I noticed a moving horizontal line on the LCD only when using the xbox 360. It turned out the computer in the next room caused this when it was on while playing the 360.I moved the computer upstairs and the problem was solved.

As of this moment my system has no "noise" and I hope it stays that way but you never know whats going to happen when adding new equipment in the future. These types of problems can be a real PITA.


I’m armed and I’m drinking. You don’t want to listen to advice from me, amigo.

-Max Payne
Re: Grounding and hum
alan #264748 06/27/09 09:17 PM
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Now that you mention it, it's the slight hiss I remember hearing, not the hum. My memory is going quicker than my ears.

Rattle and Hum and all that.


::::::: No disrespect to Axiom, but my favorite woofer is my yellow lab :::::::
Re: Grounding and hum
MarkSJohnson #264761 06/28/09 12:13 PM
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And that memory thing only gets worse.


Jack

"People generally quarrel because they cannot argue." - G. K. Chesterton
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