I am trying to use an old amp (marantz pm47 - nominal 40 watts per channel into 8Ω) with a pair of speakers (Kef Coda 7 - nominal 10-70W at 6Ω). Every so often it clicks (the same like the power-up click) and it mutes the speakers. It recovers after an inconsistent amount of time. It doesn't happen just at very loud volume. I am feeding the amp through a jack to RCA cable from a tablet. Any suggestions of what could be the cause and possible solutions?

  • What is actually muting? Or are you simply losing audio with nothing actually actively muting? – AJ Henderson Dec 16 '14 at 19:27
  • Sorry, muting is probably not the correct term. I am just losing any audio from the speakers – Dan Dec 16 '14 at 19:43
  • And I should have mentioned that when it comes back it clicks again – Dan Dec 16 '14 at 19:43

I bumped into this years ago when, as a kid, I though hey, the more speakers the better!! So I connected 3 or four sets of speakers in parallel to the little system. It would often 'click' off like you describe.

It boiled down the the ohm ratings of the amplifier and speakers being entirely mismatched.

Also, check to be sure there isn't a short in the speaker wires.

The 'click' you hear is the self-preservation mechanism of the amp that prevents DC current from reaching the speakers. See this other question...

  • Thanks, that makes a lot of sense. So could this be because I am trying to drive 6ohm speakers with an 8ohm amplifier? I have checked the speaker cables for shorts and all seems OK. Also, can you think of any tests that I could run to determine if it is the speakers or the amplifier that is faulty? – Dan Dec 18 '14 at 20:39
  • Unfortunately, I can't really offer any more in the way of the mechanics of electrical resistance and such. As far a testing, the easiest of course, would be to swap one or the other out. Try a different set of speakers with that amp. Try a different amp with those speakers. – JoshP Dec 19 '14 at 13:21
  • The accepted answer on the question I linked goes into a number of different scenarios in which the amp will 'click' off. – JoshP Dec 19 '14 at 13:24

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