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Do It Yourself

My Modular Synth




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SEM Filter


Following the change in Double side pcb instructions move to V2.

We never have enough different filters. So here is a copy of the SEM filter from Oberheim, no changes except some active components easier to find. I heard from here purist telling me this AOP and this OTA will not give exactly the same sound etc .... I am part of those who don't want to push the ball to far and I am not sure the purits hears wil make a difference.angry

This type of flter allows to get in the same time Low pass, High pass, Band pass and Notch.  I just add a reversed CV input.

Find underneath the elements for making it.

For the setup first there are 2 trimmers for offsetted the output. 1 trimmer to adjust the tracking, as this filter will not self oscillate I put for 1 Volt input 18mV at the NPN base.

The last one is to adjust the full scale of the frequency pot.

                       V1               V2


Pcb :                             

Layout :                          

BOM :                              

Wiring :          

Picture :                                 

Creation date : 19/07/2014 - 16:19
Last update : 19/05/2018 - 18:33
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