[sdiy] Vactrols

Tim Ressel timr at circuitabbey.com
Fri Jul 1 19:12:53 CEST 2016


Silonix, one of the few remaining makers of vactrols, is now called Luna 
Optoelectronics and is carried by Digikey. Their vactrols are way 
cheaper than the originals, although they are different beasts all 
together. Still, if one is hell-bent on a vactrol design you still have 

Now, I know Cool Audio still makes 5C3s. I did a side by side comparison 
between 10 'real' vactrols and 10 Cool Audio vactrols, looking at 
response times. There was a big enough difference that the Cools would 
now work for us. But they do work, don't get me wrong. Also I have heard 
a story about Cool shipping wrong parts and not making it right. Plus 
the whole $2000 minimum order is rather unfriendly.

btw that testing also brought me to the realization that vactrols suck. 
Yes I know, heresy. But in terms of unit to unit consistency, no love. 
In my VCA design I had to add trimmers so I could get the gains consistent.

--Tim Ressel
Circuit Abbey
timr at circuitabbey.com

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