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#382126 - 08/25/12 11:19 PM Re: Amplifier hum [Re: grantlyt1]
JohnK Offline
shareholder in the making

Registered: 05/11/02
Posts: 10623
The transformer could be burned out by lengthy operation at that power. What you would "blow" would more likely be your hearing in that case. The M80s are slightly above average in sensitivity and use about 1 watt for a comfortably loud average level. Brief peaks use a lot more, but are unlikely to need more than about 100 watts, which your 875 can easily handle.

Enjoy the music, not the equipment.

#382129 - 08/25/12 11:49 PM Re: Amplifier hum [Re: grantlyt1]
Gr8_White_North Offline

Registered: 07/12/09
Posts: 2231
Loc: Whitehorse YT
Which ground loop isolator did you get.
DOG is GOD spelled backwards.
What others think of me is none of my business.
M80 V3 MY GLOSS Cherry

#382130 - 08/26/12 12:03 AM Re: Amplifier hum [Re: Gr8_White_North]
grantlyt1 Offline

Registered: 08/25/12
Posts: 8

#382142 - 08/26/12 02:38 PM Re: Amplifier hum [Re: grantlyt1]
SirQuack Offline
shareholder in the making

Registered: 01/29/04
Posts: 13571
Loc: Iowa
try unplugging the sub from the wall outlet.
Anthem AVM60 Outlaw 7700 Emotiva A500 Epson 5040UB

#409051 - 12/24/14 09:25 AM Re: Amplifier hum [Re: SirQuack]
Strider53 Offline

Registered: 04/11/12
Posts: 154
Loc: Detroit
I realize this is a well beaten subject but I have a hum present in my Theatre and have not been able to eliminate it.
If I unplug the Sub from the outlet the hum is gone. Plugging the sub into a different circuit/outlet did not remove the hum. Removing the grounding screw from the Amplifier plate on the back of the sub did not help, there is an Axiom audio ground isolator in line for the cable box.
I do not use XLRs for connections.
Am out of ideas!
Any thoughts on how to proceed?

thanks, Jeff
ps- Happy Holidays

#409053 - 12/24/14 10:28 AM Re: Amplifier hum [Re: grantlyt1]
Serenity_then Offline

Registered: 03/28/14
Posts: 1565
Loc: PEI, Canada
Assuming your sub cable is decent and not vaccum abused:

Any recent changes in back of your reciever? Cables shorting perhaps? HDMI and other connections ok? Definitely seems like a stray signal or filtering issue somewhere in the chain.

I had a similar issue develop over time using an extended sub cable joined with an rca butt connector. Got grumpy with time.

I would do a hard shutdown (unplug your receiver) and reterminate if issue persists. Failing that, call axiom.

Best of luck. smile

Edit: can you run a cable direclty from your bluray/dvd/cdplayer to the sub to rule out a huge chunk of the signal chain. Even an ipod on batteries connected directly would be a good elimination test. Make you turn the sub volume off first and slowly turn up if you connect a device with no variable output. Really loud! laugh been there!

Edited by Serenity_Now (12/24/14 10:36 AM)
Trevor. Cold turkey. Thanks guys. Cheers.

#409058 - 12/24/14 12:18 PM Re: Amplifier hum [Re: grantlyt1]
exlabdriver Offline

Registered: 09/07/11
Posts: 1727
My hum was caused by my 'Cable TV' System - very, very common.

For trouble shooting, try disconnecting it at the 'F Connector' where it first joins your system.

My previous Velodyne Subs hummed until I made a jumper cable to kill it. With my EP800s, unscrewing the ground screw worked - much easier...


#409063 - 12/24/14 12:43 PM Re: Amplifier hum [Re: grantlyt1]
MatManhasgone Offline

Registered: 05/06/14
Posts: 986
Loc: Lost in the great wide yonder
I had a hum between my Axiom LFR1100 DSP and my Anthem MCA5 amp. Even with nothing else hooked up (no source) it gave a hum. Fixed it by moving to XLR cables.

it is in the way that the ground is isolated, and Axiom did it a different way than the Anthem people and thus caused the hum. You might find it's the same with your new receiver.
Anthem: AVM60
Axiom: ADA1000, LFR1100, VP180, QS8, EP500, M3, M3comp
AudioSource: Amp One/A

#409071 - 12/24/14 02:45 PM Re: Amplifier hum [Re: MatManhasgone]
Strider53 Offline

Registered: 04/11/12
Posts: 154
Loc: Detroit
So I disconnected the coax cable from the Comcast cable box, no change, unplugged the cable box, no change in the hum.
Found a 3 prong to 2 prong electrical adapter in my tool box, put it in place and no hum, none what so ever, nada, zilch, nicht!
Lucky me, back to COD or the Nut Cracker Suite.
Thanks for the suggestions!

#409073 - 12/24/14 03:49 PM Re: Amplifier hum [Re: grantlyt1]
exlabdriver Offline

Registered: 09/07/11
Posts: 1727

It is really good for one's mental health when hum finally disappears...


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