Power On Mute for PLH

FYC · 3rd April 2007, 10:20 AM

Have anyone built the PLH amp? Should we expect there can be a power-on pulse to the speaker?

I am planning to build one, and is not sure if I should include a Power On Mute or not. If I do so, will it hurt the MOSFET if the mute circuit is a NC relay short circuit of the output to GND? I prefer to use this instead of a NO relay open connecting the output to speaker as I want to avoid signal passing thru the relay contacts.

Any advices?

norb · 3rd April 2007, 06:18 PM

Having built the A75, to my surprise it didn´t show any audible thump-sound at turn-on or turn-off. Within the first second of switching on, DC offset is max. 1,5 V, and it´s a soft shaped curve. I too disliked the idea of a relay in the loudspeaker-path, so i first tried without.

If you include a NC relay you may put a resistor in series, something like 1 to 6 ohms for limiting current.

Anyway, plan on including it and keep us informed if you needed it or not.

Norbert

Nelson Pass · 3rd April 2007, 07:10 PM

I don't recall a thump, but you can short the output if you
like - the Cap will protect it.

FYC · 4th April 2007, 08:08 AM

Thanks

3rd April 2007, 10:20 AM	#1
FYC diyAudio Member Join Date: Jan 2001 Location: Hong Kong	Power On Mute for PLH Have anyone built the PLH amp? Should we expect there can be a power-on pulse to the speaker? I am planning to build one, and is not sure if I should include a Power On Mute or not. If I do so, will it hurt the MOSFET if the mute circuit is a NC relay short circuit of the output to GND? I prefer to use this instead of a NO relay open connecting the output to speaker as I want to avoid signal passing thru the relay contacts. Any advices?

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3rd April 2007, 06:18 PM	#2
norb diyAudio Member Join Date: Mar 2007 Location: Germany	Having built the A75, to my surprise it didn´t show any audible thump-sound at turn-on or turn-off. Within the first second of switching on, DC offset is max. 1,5 V, and it´s a soft shaped curve. I too disliked the idea of a relay in the loudspeaker-path, so i first tried without. If you include a NC relay you may put a resistor in series, something like 1 to 6 ohms for limiting current. Anyway, plan on including it and keep us informed if you needed it or not. Norbert

3rd April 2007, 07:10 PM	#3
Nelson Pass The one and only Join Date: Mar 2001	I don't recall a thump, but you can short the output if you like - the Cap will protect it.

4th April 2007, 08:08 AM	#4
FYC diyAudio Member Join Date: Jan 2001 Location: Hong Kong	Thanks

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