Behringer 110 VCO/VCF/VCA

I bought this to complement my Tonestar2600 in a mini-rack, adding a 2nd oscillator and filter.
The delivery from Thomann was speedy and problem free.
However, upon plugging in the module it soon became clear that scaling in the module was way off (i.e, playing 2 notes an octave apart not producing a clean octave).
The calibration trimmers are located behind the front panel and little documentation was available from Behringer on the issue.
Eventually I found a forum post explaining the procedure, removed the front and calibrated the module.
Now works like a charm and is indeed a very useful addition to the Tonestar.