APOLLO PREAMP DRIVE MK. I
5
BUILD NOTES
Setting feedback trimmer
The WIIO circuit contains a global feedback loop similar to the amplifier it’s based on. A 200k resistor
and 470n capacitor send the output from the third stage back to the point just after the gain control
between the first and second stage, which reduces the gain, cuts some of the top end, and makes it feel
more “amp-like”.
The Apollo Mk. I adds a trimmer in series with the feedback resistor, allowing the feedback to be varied
to taste. Global feedback does several things at once with the gain, EQ and compression
The stock position is between 1-2:00 on the trimmer and this should be the starting point for any builds.
From there, adjust it up or down and see if you like what it does.
If you want to omit this control, jumper the outer pins of the trimmer and use
200k
for R15.
