Hello Michael,

    Indeed, all four amp blocks have the same erratic components.

    And since I like to tweak a bit, this gave me the opportunity to add the gain control connection,

    It’s a pity that the corners of the white covers are glued and so the tabs break off.

    With a few small drops of glue, the cover can easily be reinstalled after the modification.

    I also made a few measurements this evening.

    Without external capacitor, the gain is about 180.

    With a capacitor of 100uF, the gain is a whopping 1200 !

    I believe that this amp module has a lot to offer.

    This is great for amplifying very weak audio signals like in project 89 of the legacy manual.

    And with the higher gain, even a tiny whisper from about 1 meter, the meter needle moves a lot. Even the background noise is readable !

    So, I hope that readers who have the malfunctioning amp module will find their way to this thread. It’s an easy fix to do.

    And even good working amp modules will perform better with the gain control connection.

    I will publish a circuit tomorrow which blends new and legacy parts !

    Till then !