The Baxendall tone control of the Tandberg 3002 preamp, with dual-capacitor HF and LF networks. The "op amp" was  built with discrete components and has three grounded-emitter gain stages plus a PP output stage. A similar "op amp" drives the tone control input. Values sourced from <i>Tandberg Control Amplifier 3002 Alignment Instructions - Kjeller, Norway 1981</i> . The circuit itself was invented by Peter Baxendall in 1952.
<a href="//commons.wikimedia.org/w/index.php?title=User:Retired_electrician&amp;action=edit&amp;redlink=1" class="new" title="User:Retired electrician (page does not exist)">Retired electrician</a>
<span class="int-own-work" lang="en">Own work</span>