Wednesday, 7 July 2010

DIY Quad Slew

Got a spare A-180 multiple and need a simple slew to round off jaggy gates and S&H signals? Then get out your soldering iron and follow this simple schematic from the Doepfer DIY page.



As you can hear, it's great for removing the clicks you get when feeding a VCA with abruptly changing signals:



(before and after)



Filters also benefit from 'softer' control. I built this as a companion to my Plan B M23 ASR, but you could also feed the quad slew with the outputs of a clock divider like the 4ms RCD and take these outputs directly to your VCA. A cheap and small alternative to tying-up four envelopes!

I used a 4k7 resistor and 1uF capacitor, but you could try other values for a more or less rounded result.

Thanks to fonitronik for the suggested values and help!

7 comments:

Anonymous said...

Feine Sache! Besten Dank!

Brian Biggs said...

Nice! Thanks Navs. This is perfect for the clicky horror I get when panning my A134 with the Noisering or S&H.

Brian Biggs said...

Nice! Thanks Navs. This is perfect for the clicky horror I get when panning my A134 with the Noisering or S&H.

Navs said...

Bittesch├Ân!

Let this be an end to clicky horror!

Roy said...

This is awesome. Do you know what resister and capacitor combo it would take to have a longer slew rate (say 20 or more seconds)? I'm trying to get a fade in/fade out from a gate, like a switch or a flip flop.

Navs said...

Cheers, Roy. I'm sure there's a formula to calculate times, but you might be better just experimenting with larger values. There might be some suggestions in this thread: http://www.muffwiggler.com/forum/viewtopic.php?t=18842

jernious said...

cutoff frequency formula:
f=1/(2*PI*R*C)
so bigger values -> lower freq -> more rounding

cheers!