Note: The original Jürgen Haible website is no longer active but PCBs are being released at http://www.jhaible.com.
I built a Jurgen Haible Triple Chorus in a Dotcom format for a customer and one for myself in MOTM format. The PCBs are the original from Jürgen Haible. He never published a reference diagram for this PCB. This module is unique in that it is powered only by -15V with a current draw of 62mA.
Assembly was straightforward. The MTA connectors for the Out1, Out2, and Out3 had to be trimmed slightly to fit next to the electrolytic capacitors. The two resistors to the right of the Mode switch, and the resistors on each end of the CD4011s had to be shifted to provide room these components. I was able to bend the leads of a 3 pin MTA connector to fit the footprint of the Waveform trimmer. The Mouser Piher trimmers have hexagonal slots which I don't like but these trimmers just get adjusted once. I only used sockets for the BBDs.
MOTM-PCB Mouser BOM
I used 1206 SMT capacitors on the rear.
I ran all of the panel wiring around the bottom so I could "hinge" the PCB to access the rear of the panel. I wired the Shape control so that CW corresponds to no modulation.
I had to trim the Out1, Out2, and Out3 MTA connector dust covers for increased clearance for the electrolytic capacitors.
I thought about buying the MOTM panel from Synthcube but I chose to design my own panel so I could change some labels and jacks to be more intuitive.
FrontPanelExpress HPGL design file
I only have scope images for EQ mode as chorus effect shows up as "jitter" in the waveforms. Bypass mode shows some tilt due to the capacitive coupling of the circuits.
This scope image shows the three individual outputs. The individual Out levels are lower than the Mix Out so their sum is approximately 10V pk-pk.
With a sine input and the In control set to maximum clipping is clearly visible on the outputs.
Backing the Input control down to 6 results in clean output waveforms.
This scope image shows the effect of the EQ with a setting of High EQ=10, Mid EQ=5 and Low EQ=5.
This scope image shows the effect of the EQ with a setting of High EQ=10, Mid EQ=1 and Low EQ=10.
This scope image shows the effect of the EQ with a setting of High EQ=10, Mid EQ=3 and Low EQ=8.