unusual hum from MC2102

[Masterlu]

If it’s still there, Call a Priest, lol

[mcpaf76]

this is an odd one lol

[Stahle]

Speakers humming with nothing but jumper cables hooked to them, I would start to wonder if someone was playing a prank on me.

[TOGA]

Originally Posted by Stahle

It sounds like this thread should be titled “unusual hum from JBL” because if I’m reading this correctly, the amplifier is not causing this. What a strange issue. Definitely keep us posted.

It was too late because I discovered this many hours after I posted. I think I found it during trying another output tap. That once SC out from the amp it was still hum.

And I cannot edit topic. Haha.

Toga

[TOGA]

Update :
12 hours past after I disconnected speaker from amplifier and speaker cables.
It is still humming. So there must be some energy source inside the crossover.
At first, the MC2102 was about 4 feet from PS Audio P15, and ATI AT6007 with huge transformer, so I thought may be that magnetic field
From all those huge transformer was coupled into Mac output transformer, the way we wirelessly charge the phone. I shut down P15
And ATI but it did not help. There is no large transmission tower or HV power line nearby.
I can explain the hum that it is very similar to phono preamp hum when we crank up the volume with out playing the turntable, but at a much lower level.
I hate it when it happened on Friday or Saturday because helps usually come from a time zone that is 12 hours behind. I expect to see
Some answer from JBL on my Tuesday morning.

Toga

[TOGA]

Originally Posted by Masterlu

If it’s still there, Call a Priest, lol

Where did the teak veneer on that JBL come from I started to wonder. Lol

Toga

[TOGA]

Tonight will try these.
Demagnetizing.
IMG_5272.jpgIMG_5266.jpg

[Formerly YB-2]

Any florescent or other lighting near the speakers?

[audioquest4life]

Turn off and remove the listening device or transceiver buried inside the speaker, LOL. . This sounds like some form of inductance interference or something else. Quite strange for sure. Time to do some serious testing isolating the drivers independently. If you can, disconnect the crossover cables from the drivers. This may be very difficult depending on the way the speaker is designed.

I was somewhat joking about the electrical interference. If you have a test tool that can or know someone who can measure RFI/EMI, that might prove useful. Priest is also a good recommendation��

[Charles]

Originally Posted by Masterlu

If it’s still there, Call a Priest, lol

Toga, in a situation like this I would want to know if my reference system had developed hum.

I checked my system. No hum. Hum is weird. I always expect when I turn my system on to be "business as usual" but your experience brings back my struggles with hum. Your system is "perfect", then next day you have hum. You have two systems. Check your reference system for hum.

Best

Charles