VCA click or no click switch

This is copied from the bhajis garden forum. It is Olivier response to a question about the clicky VCAs.

"The fix involves soldering a capacitor between two circuit points. The best way to do it is to solder wire on the corresponding pads, and connect them to the capacitor that smoothes out sharp edges on the envelope signal. You can even put a switch to enable/disable it.

The clicks occur with extreme settings - release time set to 0 ; or VCA receiving a gate signal instead of an envelope ; or square LFO on the VCA. You don’t have to use those settings in the first place. I personally like super fast envelopes, and love it when my SH-101 clicks (eg when disabling the envelope on the VCA and using the gate instead). The fix adds a response time to the envelopes that makes them a bit less punchy, that’s the price to pay to stay in the click-free zone."

I’m planning doing the wired switch option once I get and start putting together my shruti.

Thanks for reposting this!

The mod consists in soldering a 10uF or 4.7uF cap between one of the points in yellow in this image:

And a point connected to the ground. The sharp edges of the envelope will be dumped into the capacitor. The higher the capacity, the slower the envelope will become.

test in progress now here, i will post my feeback in some minutes :smiley:

cool. maybe a sound clip or two?

It’s delicious with a 4,7 uF! I put a switch too :wink: too smooth with the 10uF, but i found that with the 4,7 the env are speed enough, very nice for the arpegiator with short note.

I’m going to install this switch but first what Volts should the 4.7 uF capacitor be? and is the orientation of the cap: possitive to the yellow point, negative to a ground point?

You’re not going to apply high voltages to this capacitor, at max 5V - so the voltage rating shouldn’t matter much as long as it is above 5V - and for electrolytic caps this capacity the lower I’ve seen is 15V!

Positive to the yellow point, negative to the ground…

Perfect. Thank you.

The switch is in and it does sound nice.

sorry noob question… but I’m afraid to screw things up:
I’d like to apply this mod, but I’m not sure where to find a ground point on the circuit… could somebody tell me a good point where to solder the negative point of the cap?
thanks a lot!


that’s how I did it…

perfect! Thanks a lot!

I like the clicks… it reminds me of my beloved MicroWave 1;

See: “Q: Why do some synths produce clicks?” ( http://faq.waldorfian.info/faq-browse.php?product=mw )

Added the cap with a switch! works fine, thanks a lot!

I added the the cap/switch combo too (4.7 uF electrolytic) - definitely helps with the pops/clicks. Seems to also truncate a bit of the release of the gate? Anyway, it’s a nice feature, and I’m glad I put the switch in too, so I can revert to “stock” sound as well.

Alternatively, setting the VCA attack to around 10 virtually eliminates the click.

That’s interesting glitched - for me I have found many instances where the click seems independent of the envelope settings… what sort of pushed the issue of me trying this mod.

i’m finding the vca quite clicky on my shrutHi. do the same pins between the 3379 on the filter board (3379 board in my shruthi) and the atmega on the control board still apply here?

Try replacing the 22nF cap connected to the VCA line by a 100nF.

roger that! thanks olivier. thats c5 right?