I reverse engineered a Doepfer A130-8
which consists of 8 VCAs with 3 summing outputs (actually a great module as it is!) and added an extra pcb panel to it with a flatcable connector so that I can inject signals in it from another module I’m working on without having to use the jacks. The 2 Doepfer PCB’s (the green ones) are held together by 3 connectors. I used these connectors to put my pcb (black) in between the 2.
i finished it but not tested yet, and i built the stripboard version from @EddyBergman , not sure if it’s exactly the same.
what is the use of the trimpot on your circuit ?
or maybe you can add directely a trimpot on resonance potentiometer to control the way .
I forgot the beginning of a stripboard in a corner : I finished the Megamodule.
I also finished the PCB part of the Dual Quantizer but I am missing 5 resistors of 1K !!! to finish it completely for now.
LOL , you sir are on a roll today thanks for the chuckles 
I’ve found that more people have problems to get this design to work properly. In his video on the Yusynth Steiner Parker filter, Markus Fuller speaks of playing about with some resistor values before he got it to work:
The feedback part of the filter is implemented differently in the 3 versions I found on the yusynth site. Given that the ‘improved’ version is giving me problems, I will try one of the others.
on his website Yves Usson made an update for the resonance in 2012.
he said :
“This is my new version of the Steiner-Parker VCF VCF. This time I tried to improve the design to correct some problems with the original circuit: remove the crackles of the resonance potentiometer (complete redesign of the resonance circuit), tame the chaotic behavior of self-oscillation. "
but that was in 2012 (1 nov) ! is that @THOGRE bought an old version still in stock ? or there is a problem with all ?
he speak also about the resonance pot, you can use a reverse audio pot or a linear but with a 100k resistor :
and here for settings :
Start by adjusting the trimmers halfway.
Adjusting the CV rejection (trimmer T2)
Set the audio potentiometer to 0.
Set the cut-off potentiometer halfway
Inject into the CONTROL # 1 input a square wave (LFO or VCO) at a frequency of 50H and set CONTROL LEVEL # 1 to maximum.
Connect the output to an amplifier or oscilloscope, you should hear low frequency sound or see modulation on the screen.
Adjust T2 so as to minimize (and if possible eliminate) this low frequency sound. IN principle if the transistors have been matched correctly then the setting of T2 should be close to halfway.
Adjustment of V / OCT tracking (trimmer T1)
Connect a CV / GATE keyboard or an adjustable source to the V / OCT jack.
Set the resonance to self-oscillation.
Adjust the 2K trimmer so that you get V / octave tracking. This should be possible over 3 octaves.
I got the PCB as a gift from a friend, but he has the same problems, I also considered the matter with the 100k resistor on the potentiometer.
all the information in my post come from YU website, so it’s for the PCB.
and on the boom i see it’s a 47K or 50K reverse audio curve for resonance pot .
in a french forum :
YU :
“For R18 it is 4.7K a priori but if you refer to the diagram this resistor is marked with a double asterisk and on the diagram this double asterisk is referenced “this resistance value can be modified to adjust the resonance range”, in other words, the value of this resistance is not fixed and it is up to whoever makes the filter to determine the value corresponding to his wishes in terms of self-oscillation of the filter.”
maybe use a trimpot instead of R18
Interesting discussion, maybe one of you should create a new topic for it? Otherwise I’m afraid it’ll be very hard to find later on if I ever build one…
Maybe we should really open a new thread like @analogoutput analogoutput says, I used a potentiometer for R18. or I have pin sockets to quickly change the resistor.
Ha, a double layer vero board! I’ve not seen that before on this forum.
This is PLUMROOLZ.
KOSROLZ is based on this circuit 
Voltage controlled Rolz - verso and inverso inputs - exponential convertor x multi-vibrator circuit - tempo pot controls the expo - and feeds voltage into the multi-vibrator to sort of adjust the “rate” of the rolz. - I guess you could say it adjusts the delay time between the charge and dump of the caps.
I had a small brain wave this morning and built a little platform for my sequencer box. Now the Keystep can go directly in front of it, and still have a place for the cables on the back to go.
The box on the right will have 1/4 outputs connected to the Keysteps’ rear pitch, gate, mod, and sync outputs; And some 1/4 > 1/8 converters.
nice , like the " patch bay " idea much easier than dragging the keystep out every time you need to change something .
But i´m not the first one i´m pretty sure @Doolang did the same with his Steiner Parker Filter.
First module tested, the TWIN T Kick Drum, which I made in a stripboard version.
This module is to replace a simple Drum Kick in my case 2. it was very limited, no tune …
Maybe just a little thing to know, the Decay increase and decrease also a little the Tune in this module.
Let me guess, the most time consuming part of the build was putting the nut on the bolt? 
I was not the right size, I tried to cut one with a saw and afterwards impossible to fit the nut in the thread , one other bad test … so I left it long,and she didn’t bother
