Pioneer PD9700 analogue stage question


2008-01-10 10:46 pm
Hi. I was just curious to know, do R577 & C567 (see schematic) form a (12KHz) low pass filter? The stage is described as 'Buffer & de-emphasis' & I wondered if this was intended to actually filter the audio signal rather than decouple digital/RF noise.

Thanks, Paul


  • Output stage.JPG
    Output stage.JPG
    71.4 KB · Views: 61


Paid Member
2007-09-15 8:14 am
The whole opamp stage forms what's called a "multiple feedback" filter and is inverting at DC. The opamp is configured as an integrator (C565) and it's performance is hugely opamp dependant. That may be one reason why the stage uses FET's to boost output stage current delivery.