Steiner PCB - Stooge panel assembly help

Abby Normal · Joined: Feb 20, 2010 Posts: 66 Location: USA Audio files: 2

Hello, I'm finally getting around to building my rev. 1 Steiner filter (after 7 years!). Back then, I bought a Stooge panel for it which has the following control pots:

Frequency
Resonance
HP In
LP In
BP In
AP Mix (Wet/Dry)
FM1
FM2

For a schematic reference, here's a link to the Steiner page on Ken's site:

http://www.cgs.synth.net/modules/cgs35_syntha_vcf.html

The schematic indicates the pot values for Freq. and Res. For all of the other panel pots, can I use 100K linear pots?

I plan to wire the FM 1 input via a 100K lin pot, and then directly to the PCB CV input. For the FM 2 input, I'm pretty sure that I should add an additional 220K resistor from the FM 2 pot wiper to the base of the 2N2222. Is this correct?

For the AP In (Wet/Dry) pot, I have NO CLUE. Can anyone help with this please?

For the AP input jack, I read that this should be connected to all three inputs. I also read that it should only be connected to the LP and HP to form a "true" all pass (flat) response. The person who wrote that stated that connecting the BP input would result in a peak at the cutoff frequency (which makes sense). Since my panel has input level pots, I plan to just turn the BP input pot down for a "true" response, but would like the capability of raising the BP level for something unique. How did everyone else wire their all pass input?

Thanks for any help/comments. I hope someone has the same panel that I do. I'd be curious to hear how your panel is wired.

Thanks again!

Mongo1 · Joined: Aug 11, 2011 Posts: 411 Location: Raleigh NC

Hi Abby,
I don't have this board, but nobody else has answered so I'll give it a try....

Abby Normal · Joined: Feb 20, 2010 Posts: 66 Location: USA Audio files: 2

Thanks so much for the reply Gary. I was thinking that the AP Mix pot would have one side connected to the AP input jack, and the other side of the pot would be the "stock" filter output, and the wiper of the pot would be the new filter output. Problem with that is that the Mix pot would have to be set to WET if using the other inputs (not the AP In) to hear anything.

I did read on someone's website that additional CV inputs might need a buffer circuit.

I'll have to think about this some more....