Originally Posted by porschedrifter
I've noticed the 608 will give a single click noise (not through speakers, the click noise you hear when powering off or on AVR) about 10 minutes or so into being on, for no reason, no source change or anything, just while playing music with no user input at all.
My z2 is set as z2, not fw or fh. Center is turned off.
Is this a normal thing?
The click is for a reason, as I have posted before the 608 has an energy saving feature where it can run the output stage DC rails at 2 different voltages depending on how much power is being called for. Mine halves the idle wattage draw when that relay clicks from high to low, and yes the delay is roughly 10 minutes.
If you slowly turn the volume up after the high-low click you will hit a certain level (not a certain number) and it will click again as it switches back to high.
Look at it this way, if you are only sending 1 watt to an 8 ohm speaker on a 100 watt receiver you are sending it 2.83 volts AC, 100 watts @ 8 ohms is a 28.3 volt AC sine wave, to "slice" that sine wave out of symmetrical DC rails you need a rail voltage of at least 41 volts DC, HT mags stereo wattage test comes out to about 46 volts DC, and the service manual says 54.5.
As you can see slicing 2.83 volts AC out of at least 46 volts DC will cause lots of heat, IE 1 watt goes to the speaker and ~18 watts goes to the heatsink.
To combat this the 608's output stage lowers the rail voltages when the full wattage capability isn't required.