Question about behaviour of Polivoks vs. everything else

I’ve had a Polivoks Shruthi for quite awhile and there’s something I have always wondered about. Watch this 20sec video:


Here are six Shruthis, with the Polivoks being the one sounding the Bb. They are all playing the same patch. Notice the thump? The PV is the only one that does this. I can often edit the patch, adding a bit of release to the filter env usually helps, but sometimes nothing I do gets rid of the thump completely.

I was just wondering if this is the expected behaviour from this filter board?

One of your tines is loose. Just open up your EP and tighten it up. You may want to make sure the dampener isn’t stuck on it either.

Whew! I was actually going to try a bigger hammer.

Sound a bit like some DC voltage is coming thru ?

How could I tell?

Do you have a scope? It actually sounds like a DC-blocking cap is not doing its job, and the signal that hits the VCA has a big DC offset so the envelope signal bleeds through.

I don’t have a scope, should I just replace a cap or two? I didn’t build this one. Maybe it’s time to consider getting a scope…

Anybody wanna chime in here? Which caps are the DC blocking caps?

The 4.7u or 3.3u ones.

C24, C25, C27, C1 the Bipolar 4,7µ - Are they really bipolar?

Thanks, I’ll check. I’m beginning to realize I am either bipolar or have been put into this world with reversed polarity.

Do you have an Aunty Phase in your family?

This one is cool and it’s DIY. Good for most things synth…

yewtreemagic, I have all sorts of oddness in my family.mmarsh, that’s quite inexpensive, is it actually good enough!?

I use it all the time :slight_smile:

That’s a great kit! I need one of those.

It’s been pointed out elsewhere, but it does bear repeating: this little scope is inexpensive and cool, but will only handle audio frequencies. For analog audio stuff, it’s perfect.

Checked C24, C25, C27, C1 the Bipolar 4,7µ – they are really bipolar and correctly oriented. They also look okay, no rounded tops or anything to indicate any problems. Should I replace them anyways?

I did, seems a bit better but still not quite right.