Compressor questions

[Mark Hammer]

Nice. Some good insight there..


However there are always more questions.

Re the rolls ducker.

http://www.rolls.com/pdf/M_DU30b.pdf

How does it attenuate? Which parts. The J113s?

Would removing the mic pre have a significant effect? Or is it kinda tied to the other inputs?


Or is it a similar method to what PAIA did with theirs?

http://www.freeinfosociety.com/electronics/schemview.php?id=1092

I'm a long way from done wasting my time with some mods and stuff but I have much to learn.

Cheers
Rich

The answer is Yes.  The J113s are used as voltage-controlled resistors to attenuate the line signal coming in from J2C and J2D.  One can either eliminate everything leading up to, and including R9, so that only J2A/J2B line in signal does the ducking, or use the mic pre-amp and eliminate the line in to have voice do the ducking of the other line-in signal.

Note that duckers work in sort of reverse from gates.  The signal coming in J2C/J2D passes through undisturbed, with Q1/Q2 maintaining maximum off resistance so that there is no attenuation.  When the announcer speaks into the mic, or some other line-level signal is fed in through J2A/J2B, Q1/Q2 are turned on and their drain-source resistance drops, attenuating that signal.  This is what normally allows an announcer to talk over music on the radio, and have the music come back up after they shut up.

The mic preamp is fed to the envelope-follower section comprised of U3A/3B, but also fed to P1, whose mono output is fed to both U2A/2B via R16/R17.  That is both line-ins are maintained in stereo, while the mic in is used in mon but output via both channels.

[Kipper4]

I had a feeling that it was something like that.
Thanks Mark.

[Kipper4]

Heres a theoretic redraw of the Paia Stereo Ducker (ducker only)

[Juan Wayne]

Feedback closes the stable door after the horse has bolted.
Feedforward closes the door before the horse is stabled.

If you're not already a teacher, you should be one. I could have used one like you back when I was studying. I got a shitty washing machine example. We all felt somewhat redeemed when the guy lost a tooth in class. That's how much we hated him.