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It looks like the mute pin for the LM4780 is just tied to ground via a 10k ohm resistor, making the amp never mute. Is it possible to instead tie a switch off to the pads to add a mute switch? Or to add a soft start circuit (per the TI manual on the 4780) using a capacitor tied to ground?
Would using soft start eliminate any turn on thump (or is there no thump heard in the default configuration)?
Thanks!
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You could certainly add a mute function, but there are no transients at turn-on or turn-off.
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The Lm47080 is just one part of the entire amp, and it's output is part of a larger feedback loop. You shouldn't mute the LM4780 on its own. In any case as Brian said, it is completely not necessary, there is no thump.
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Rank: Member
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OK, good info - thanks!
On an unrelated topic, if I wanted to run 4 amps in total (2 per speaker for bi-amping) what transformers should I be using? Would two +/-25VAC 600VA transformers cover my needs?
What about a crossover - would I need a crossover if I was bi-amping? And would I want to put it in the input side, or the output side?
Thanks again!
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I would try to use one transformer per amp, but it is ok to share.
600VA should be fine even for two amps so long as you keep the output expectations reasonable. :)
You could do the crossover either way. If you speakers have a split passive crossover for bi-amping then you need only use that.
Otherwise you may want an active (or passive) crossover at the input to the amps.
Cheers!
Russ
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