Hey all,

I'm the owner of a Marshall MC412A 4x12 and just today at band practice it seems to have kicked the bucket. I figured it was just a speaker that blew or something, but after i switched the setting from Mono to Stereo on the back plate, it works just fine with one set of speakers. It works on both the 16 and 4 ohm jacks when in stereo as well, which is extra puzzling and then when I turn it back to Mono, neither jack produces any sound or it is very very quiet until i turn the volume past 9 o clock which is when it decides to not put out any sound at all. Is this an issue with the jack plate assembly or something else? Was just wondering if anyone else ran into the same problem. 

Thanks in advance.
You probably have a loose wire in the cabinet. Have you considered looking inside?

Probably a bad idea to run the volume up to 9 on the amp if you know there's a good chance you don't have a load connected.
I would wager that a wire fell off.

+1 to dspellman
WTLT 2014 GG&A

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