Clicking when resonance low

[veracohr]

Hi there, I'm hoping someone can help me with this.

My x0x makes a bit of a clicking sound at the beginning of a note when the resonance and cutoff are low. When the resonance is turned up it either goes away or isn't noticeable anymore. It's a hi(ish) frequency sound, so when the cutoff is turned up it gets masked by the normal harmonics of the sound. I'm pretty sure I've heard x0x lines that didn't have this sound, so I don't think it's normal. Curiously, my BassStation Rack does this too, always has, I just dealt with it. However, I figure since I built the x0x, I may be able to fix it (if there's anything to be fixed). I didn't even notice it until I wanted to use the x0x for bass instead of an acid line (gasp!)

This sound has cutoff, resonance and envelope mod at minimum, decay at maximum:

http://www.veracohr.com/audio/x0x-click.wav

[SubStyler]

hi!
your x0xb0x uses the BA6110?
you can try this: get a 1k resistor and a 1µF tantalum capacitor.
solder the positive side of the cap to the base of Q1 and the 1k resitor to the negative side of the tantalum cap. the other side of the 1k resistor to ground.
this should almost eliminate the click.

[veracohr]

Yes I have the BA6110.

What does your suggestion do - filter the envelope feeding the OTA? Any idea why mine does this and others don't?

[antto]

this is the VCA-Gate click, it's present in probably all x0xes and 303s (altho, in the 303s it could be slightly different)
there is a big thread about it in the x0xm0dz section

[veracohr]

Really? Huh. I'll look for that thread. Thanks.

[antto]

viewtopic.php?f=13&t=16764
here it is

btw, in the thread some were talking about other types of clicking too, so watch out
there's at least one other type of click in the x0x and that's the "DC offset" type of click
play some fast pattern, and move the waveform switch in the middle (where it's neither connected to the sawtooth nor the square wave) this now feeds <silence> to the filter and onwards
but if there's DC offset - it would be audiable (low frequency pops)

so don't confuse the different types of clicking
from your audio file - you have just the VCA-Gate click (i have posted a drawing in the thread on the first page showing the click shape)

[veracohr]

I could have sworn I'd posted a reply to this, but:

I started with SubStyler's suggestion and ended up with something even simpler. A 0.56uF capacitor from the base of Q3/Q4 to ground. The easiest way was from the base to emitter of Q3 - the outer two pins. I just soldered the capacitor on the back side of the board (with the components facing down and pots facing up). Works like a charm!