Lighthaus

The “Lighthaus” is my attempt at grasping the essence of the excellent high-gain circuit “Openhaus”, while also addressing what I personally find to be unnecessary or less good. One of the main goals was to reduce the component count, noticeably the costly opamps, and trying to use standardized values as much as possible; a stripped down, light-weight version.

– The expression jack and the extra input buffer has been removed.
– The power section has been reworked for standard +9V using a voltage doubler.- The 3-way gain mode switch has been reduced to a 2-way switch so it can be made “stomp-able”.
– The active tone stack that comprised almost half the circuit and was using three opamps has been entirely replaced by an active Baxandall treble/bass section and a matching mid control, using only one opamp (those OPA2604’s are really expensive!).
– The mid voicing and phase switching controls have been removed.

Overall I’m very happy with how it turned out, though I’m still not very happy having to rely on 1N1306 germanium transistors. I would like to find something that’s easier to source, but still sounds great. Suggestions are welcome 🙂

The circuit is a great deal smaller than the (quite large) Openhaus layout I did many years ago, so fitting this in a standard 1590BB was perfectly doable. (Forgive my poor “late at night” photos).

I didn’t get to keep mine many days before it saw it’s way into my friends hands, who is now actively gigging with it. Very happy with that as well, although I will have to build a new one for myself.