Buchla 291 Dual Voltage Controlled Filter

This is the first module towards a Buchla 200 clone: The Buchla 291 dual voltage controlled filter. Using Mark Verbos’ PCB design (scroll down to “Buchla Bandpass Filter”) I made some minor adjustments and etched the PCB.

Buchla 291 - PCB based on design of Mark Verbos

After soldering the PCB I started designing the front panel in Front Panel Designer using a picture of the original front panel for reference.

Buchla 291 - Designing the front panel

I’m using 16mm Alpha pots for the front panel, banana jacks and 3.5 mm jacks. I had the basic layout pretty fast but tweaking until everything was right took a bit longer. To be absolutely sure everything would fit I decided to make a prototype front panel using scrap wood so I could see if everything would fit like I thought it would. I printed the design and drilled the wooden panel.

Buchla 291 - PCB and front panel prototype

Then I mounted the front panel components. The 3.5 mm audio jacks didn’t fit as the wood I used had a thickness of 5 mm and the jacks can only be mounted on panel with a maximum thickness of 2 mm.

Buchla 291 - Front panel prototype

And everything fits! Time to order a professionally silk screened front panel.

Buchla 291 - assembled prototype

To be continued…


  1. snaper

    Any chance for an FPD file for this filter?

  2. Hi,

    Where did you get that blue PCB?