# 1184 quad mixer vca (AKA 1183) **URL:** \ **Category:** KOSMO MODULES\ **Created:** [March 27, 2020, 2:27pm UTC](https://lookmumnocomputer.discourse.group/t/1184-quad-mixer-vca-aka-1183/455 "2020-03-27T14:27:11Z")\ **Posts on this page:** 1\ **Showing post:** 10
**Author:** ![fredrik](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/fredrik/32/682_2.png) [@fredrik](https://lookmumnocomputer.discourse.group/u/fredrik)\ **Post date:** [May 16, 2020, 1:09pm UTC](https://lookmumnocomputer.discourse.group/t/1184-quad-mixer-vca-aka-1183/455/10 "2020-05-16T13:09:13Z")
> [@sebastian](#): > > Can anyone explain this a bit more to me? Not sure where that 2 V comes from – the 3360’s inputs and outputs are current driven with a ±400 uA max range. The input stage matches the datasheet, with an added inverting buffer followed by the datasheet’s 47k that maps ±10 V (20 Vpp) to ±200 uA, which is within range. I don’t see what the diode is doing there; seems to me you could just leave it out… The output is also a little bit odd – output is a ±200 uA current at max gain (1.0×), so you’d expect there to either be a resistor to ground (datasheet uses a 47k to shift back to ±10 V) followed by an inverting buffer, or a straight I-to-V stage (signal directly into an opamp with a 47k feedback resistor), but I guess the two 100k resistors have the same effect? You could probably replace that with a piece of wire and ~~a 47k~~ one 100k if you’re a bit adventurous 🙂 EDIT: You’d have keep the 100k feedback to get the same output voltage. The first 100k doesn’t really do anything, what I can tell (after turning on some more braincells), since the current doesn’t have anywhere else to go but through it. You could probably use any value there. Or a 0 ohm link. --- _[View the full topic](https://lookmumnocomputer.discourse.group/t/1184-quad-mixer-vca-aka-1183/455)._