# Dual VCA / Mixer / Crossfader / Panner **URL:** \ **Category:** KOSMO MODULES\ **Created:** [September 24, 2024, 8:50am UTC](https://lookmumnocomputer.discourse.group/t/dual-vca-mixer-crossfader-panner/7552 "2024-09-24T08:50:26Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Krakenpine](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/krakenpine/32/3263_2.png) [@Krakenpine](https://lookmumnocomputer.discourse.group/u/Krakenpine)\ **Post date:** [September 24, 2024, 8:50am UTC](https://lookmumnocomputer.discourse.group/t/dual-vca-mixer-crossfader-panner/7552/1 "2024-09-24T08:50:26Z")
I designed a simple dual VCA with AS3360 chip. Basically it’s just two VCAs, but there is also a third output that that sums the other outputs and third CV input, which controls channel 1 directly, but channel 2 as inverted. So, you can put two signals in and with that third CV select which one is coming out from the mixed output. Or put one signal in, as input 1 is normalled to input 2, and use outputs 1 and 2 and use this to pan signal. My main application for this is to mix two outputs of an oscillator module and/or two separate oscillators. Or this overkill of two #1222s and three of these dual VCA:s to have any combination of both of their square and saw waves. And then a seventh VCA for “normal” VCA function. Anyway here’s schematic: ![image](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/f/8/f8c8a3eae8756c3b43d0add53b420396ebf752db.png) And KiCad-files (no gerbers, but you should be able to export them, and remember to add your own funny picture in the middle of the front plate): > **[krakenpine-synthing/dual-vca-kosmo at main · Krakenpine/krakenpine-synthing](https://github.com/Krakenpine/krakenpine-synthing/tree/main/dual-vca-kosmo)** > > Synth modules? Contribute to Krakenpine/krakenpine-synthing development by creating an account on GitHub. I like goblins: ![IMG_20230605_215627](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/6/2/623857cafa3d1100af2a874efd0768d7beccab6a.jpeg) And here’s a video where I ramble about this: [![](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/c/d/cd96a27ac622de196712a72d3d37efca3a363aa5.jpeg "DIY Kosmo modular synth dual VCA module") ](https://www.youtube.com/watch?v=iGI92x8AyZQ) Disclaimer, I haven’t actually build that version 1.0, I did a previous iteration that had couple of bugs that I corrected on the pcb and hopefully fixed properly in the schematic. ---
**Author:** ![Sandelinos](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/sandelinos/32/27423_2.png) [@Sandelinos](https://lookmumnocomputer.discourse.group/u/Sandelinos)\ **Post date:** [September 24, 2024, 1:21pm UTC](https://lookmumnocomputer.discourse.group/t/dual-vca-mixer-crossfader-panner/7552/2 "2024-09-24T13:21:01Z")
I saw your video yesterday but forgot to leave a comment. Great that you’re on this forum as well. The mixed output and the crossfade / pan CV input are great features and I’m totally going to steal them whenever I make my next VCA. I see one mistake in the schematic. Those diodes `D5`, `D6` that you want to clip off negative CVs aren’t having any effect because you’re taking the output from the wrong side of the 10k resistor. PS: It’s nice to see fellow finnish people making synths ---
**Author:** ![Krakenpine](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/krakenpine/32/3263_2.png) [@Krakenpine](https://lookmumnocomputer.discourse.group/u/Krakenpine)\ **Post date:** [September 24, 2024, 1:43pm UTC](https://lookmumnocomputer.discourse.group/t/dual-vca-mixer-crossfader-panner/7552/3 "2024-09-24T13:43:59Z")
Well yeah, that’s a mistake. I’ve built enough distortion pedals that I should know better. Technically I wouldn’t want to have 10k and 100k resistors in series as that would affect the gain. 1k resistor would be within other tolerances of that gain, but then -10 volt CV voltage would have extra 10 mA of current draw. But I really can’t say is that a lot in a larger scheme of things. Or maybe it is if I measured correctly that without input signal this module takes about 40 mA current from the +12V and 25 mA from -12V. So maybe I correct the schematic and change the 100k resistor to 90k? ---
**Author:** ![Sandelinos](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/sandelinos/32/27423_2.png) [@Sandelinos](https://lookmumnocomputer.discourse.group/u/Sandelinos)\ **Post date:** [September 24, 2024, 1:48pm UTC](https://lookmumnocomputer.discourse.group/t/dual-vca-mixer-crossfader-panner/7552/4 "2024-09-24T13:48:50Z")
90k is not a standard resistor value so it might be hard to find. You could replace the 10k with a 22k, and the 100k in the opamp feedback path with a 120k and that would keep the relationship pretty close while using commonly available standard resistor values. ---
**Author:** ![Krakenpine](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/krakenpine/32/3263_2.png) [@Krakenpine](https://lookmumnocomputer.discourse.group/u/Krakenpine)\ **Post date:** [September 24, 2024, 2:55pm UTC](https://lookmumnocomputer.discourse.group/t/dual-vca-mixer-crossfader-panner/7552/5 "2024-09-24T14:55:51Z")
Standard resistor values is something I need to remember to take into consideration. I’ve always had a luxury of a nearby electronics shop that has even all the non-common values.