Why another Moog Ladder Filter? There are many decent implementations out there in the SDIY domain. Any reasons beside the joy of making something yourself? Well, I wanted to have some features that are not found in this combination elsewhere. First of all I wanted to get rid of loosing gain when the emphasis / feedback is turned up. And I wanted to bring all filter poles out. This means 6dB, 12dB, 18dB and 24dB outputs (Discussed in my next post). As a side effect off the gain corrections I got the emphasis voltage controlled as well. The feedback loop can be opened so you can bring in some filtering or what ever you want in the feedback loop. The exponential circuit can be stuffed with discrete transistors or LM394 as well. And this circuit is temperature compensated with KTY81-110.
Moog Ladder Filter with LM394
The PCB is made for use with ordinary (matched) transistors and with matched pairs like LM394.
Moog Ladder Filter with discrete Transistors
The schematic:
Moog Ladder Filter schematic
Some closeups:
Moog Ladder Filter LM394 closeup
Moog Ladder Filter with discrete transistors closeup
Moog Ladder Filter temperature compensation with KTY81-110 and discrete transistors
Moog Ladder Filter temperature compensation with KTY81-110 and LM39