AC DC VCA Quick question

joshco · Joined: Nov 14, 2008 Posts: 48 Location: germany

Hello,
Currently I´m building some VCA´s, theres a DC and a AC Version.
What does this mean in general, are there any differences in sound or in amplification?

Thanks
best regards

yusynth · Joined: Nov 24, 2005 Posts: 1162 Location: France

The AC version is solely dedicated to process audio signals that's why there are capacitors in series with the INPUTS. These capacitors are there to filter out any DC component.

The DC version is more versatile because it can be used for processing either CVs or audio signals.

joshco · Joined: Nov 14, 2008 Posts: 48 Location: germany

Allright, the caps remove the dc signal in the audio material, whereas the DC version is able to amplify DC signals too.
Thank you!

robboten · Joined: Nov 26, 2009 Posts: 22 Location: stockholm, sweden

In the schematic for the simple VCA module there are two stars at the LED and the circuit around it. Does that mean that the LED only works with the AC version? That could explain why I get no light... And if so, is it possible to have light with the DC version as well?

yusynth · Joined: Nov 24, 2005 Posts: 1162 Location: France

If you have installed all these optional components and use it in DC mode then the LED can bright but only for a negative input voltage. The LED circuit was designed for AC only as indicated.

robboten · Joined: Nov 26, 2009 Posts: 22 Location: stockholm, sweden

Ah, I see. Thank you for your reply!

And also a big <3 for all your work on the modules you have published! I just love everything about them! The clearness of the pictures, the easy to follow schematics, the pcb-layouts and the functions. For me as a noob on the field this has helped me understand so much! Build my fourth module today (Noise, VCA, ADSR, S&H) and is so happy about it all! Next up is a mixer or the Steiner VCF. Probably ending up with all of them sooner or later... it's so much fun! So thank you again so much!