A4 MKII Filter Oscillation for Kick Drums

I’ve been eyeing the A4 MKII lately, particularly for use as a drum synth. Had an excellent jam with it at a friend’s house recently and found it a lot more satisfying for drums than the AR, which I had for a while before selling. When synthesizing kicks, I was mostly using the triangle waveform and fine tuning with the filters, which sounded fantastic, but i couldn’t manage to create satisfying filter envelope kicks (i.e. without using the oscillators) like I can on my Pulse 2, which allows me to get cleaner sine/808-style kicks. This raised a couple of curiosities that A4 MKII users/filter experts might be able to shed some light on.

First, I noticed that the ladder filter doesn’t self oscillate nearly as strongly or consistently as the multimode filter. This seems to make it unsuitable for filter kicks, which is a bit of a shame as it would be lovely to be able to do this and then further tailor the kick with the multimode filter thereafter. I’ve never had a piece of gear with a ladder filter; is this weak self-oscillation a trait inherent to ladder filters in particular? I don’t have access to the unit anymore, so do any A4 MKII owners know if using the oscillator feedback function would allow the ladder filter to self oscillate enough for synthesizing smooth siney kicks? The multimode filter didn’t show much promise for filter kicks either, particularly since the overdrive comes before it in the signal chain and doesn’t allow me to get the emphasis I need without having to neighbor to the next track.

Unless I just need to spend more time getting to know the A4’s filters and their envelopes, I assume the CV-output-to-external-input trick is probably the only way to get a good sine kick out of it, which is probably preferable in the long run since it doesn’t eat up any track space. In short, do any A4 MKII owners have much experience using the filters for this purpose?

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Thanks! I read this thread a while back and messed with trig note lengths during my original jam to try and get more pronounced behavior from the multimode filter. It was giving me great 909 style kicks but still not the clean 808-style sine I’m looking for. It’s probably a matter of finessing it a bit more, I’ll see if I can give it another visit.

Still curious to know if using the oscillator feedback function will let me get stronger self-oscillation from the resonance of the ladder filter. Might as well just investigate next time I get my hands on the unit.

The Recipe is here @d_hansen

You should find a lot of article in this thread regarding the LOWEND and Analog Four techniques, i was about to finish definitively the booklet it’s for Christmas 2018

Also Umonox have an interesting way of modulating the behavior regarding notes … definitively a tutorial to watch and understand


My experience is that you can get punchy kicks with resonant filter 1 and resonant peak or highpass filt2 boost of the low end but the resonance of filt 1 has to be turned to maximum which introduces some noise. Can be nice though.
But filter 2 has more range for self resonance.
I like a combination of pitch modulated triangle osc and resonant filter 2.
Using an “single cycle” exponential lfo for the modulations
Have to check it with feedback

Talking about A4 mk1 btw.

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Excellent, that first vid seems to get closer to a proper sine kick than I was able to, particularly around 9:40. I’ll take note of how the envelopes are being set there. The Umonox vid will be very useful for basslines indeed. Will read through the thread for LOWEND, thank you!

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Ah yeah, next time I should try using the LFOs rather than the dedicated envelopes and seeing if it yields a noticeable difference for the filter.


My memory is feedback blurs the sound and takes the punch out of it.

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To get more sine sound from a tri osc you can also try Keytrack = 32 for filter 1, freq around 53, set by ear.


feedback is pretty unpredictable. depends on osc volume, resonance, overdrive etc. small adjustments - big changes in sound. It can add a lot of low end but i only tried for bass sounds


Interesting, is this to attenuate the partials proportionately to pitch?

Makes sense, and I imagine it would only add more partials and take me even further from a sine.

Totally, reducing harmonics, much closer to a sine.

Oh yeah, I was using the filter to reduce partials to bring the triangle closer to a sine before, but how come the keytracking?

The idea is to follow root note with keytracking to keep fundamental frequency. With my A4, it works with filter 1 set to 53, keytrack 32, after a calibration (not especially necessary). Can be done with filter 2 too.

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Also you can use OSC 1 for transient part and OSC 2 or Filter Self-resonance for Punch and Tail
or a combination of everything… A kick is not just a sinewave where you use pitch envelope to get the clicky beginning part + the Punch you can separate in two elements or 3 etc… (Like Layering Sound Design)

You can use a SAW for the clicky part (fairly short it’s a transient around 10ms) even introduce FM LFO on this part for some Kick definition (to taste), just assume a good mixing between the 2 Layers

And LFO + (or) ENV to shape things and get proper timing. You can also plug your A4 through computer and passing the signal through Bram S(M)excoscope and Spectrum (so you can tame visually your transient (clicky part) and get a very well designed kick that way…

s(M)exoscope is now in 64bits

Good startpoint for the fundamental are :
808 Kick : G0 \ 909 Kick : A0

Click duration : around 10ms
Punch duration : around 100ms
Tail duration : to taste
Pitch envelope can go to 2/4 octave higher for the Pitch modulation (duration : to taste but generally fast…)


Ah I see, that had never occurred to me. Great tip.

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