Tempest Recipes: Donk Bass

January 15, 2013

That familiar hollow ‘thwank’, mainstay of a gazillion garage records. Nevertheless a great foundation for our own, less cheesy variants.

  • Start with a square wave on Osc2 and set Osc mix to 0/100 so we only hear Osc2.
  • Use a 12dB filter with cutoff at 40 and a modest amount of resonance to start – say 30 also. Set filter keytracking to 15 or thereabouts. (To access this parameter, on the filter screen press the right arrow. The parameter is called LP KEY>FREQ).
  • Now use the Filter envelope to get our ‘twang’. Perhaps a decay of 60 and amount of 20-30. A pinch of velocity control – but not too much as we want to keep the filter fairly subdued. Bend it if you wish.
  • To give more volume, change the amp envelope amount to 32 and reduce it’s velocity sensitivity to 64 also (in general a nice compromise, I find).
  • You could also try adding a little pitch envelope – but short and barely noticeably to give the attack more interest.

Now we’ll apply some FM. Fellow fans of FM synthesis will know that the most pleasing sounds pop out when the frequency of the modulator(s) is at integer ratios of the carrier’s frequency. As we detune the frequency of the modulators we hear first a vibrato effect on the carrier. As we detune further we are led into to the familiar clangorous tones that only FM can do. Well, the same principle applies on the Tempest, although less dramtically. Nevertheless useful to know.

Even if you don’t understand FM, you can easily hear this difference. Osc1 is our modulator (which we don’t hear) and Osc2 (or more correctly, the filter input) is our carrier – what we hear. So…

  • ..put another square wave in Osc1 and set it’s pitch to one octave above Osc2 (C5 if you left Osc 2 at at default). Now turn-up the Filter FM (Audio mod) about half way. The sound should become perceptibly more hollow. Play with the filter and it’s envelope until you get the sound you want – in my case a bouncy bass where the harsher frequencies are still filtered out.

Now if you change the frequency of OSC1, one semitone at a time, you will notice the tone becoming less ‘pleasing’ and more metallic at certain ratios, but seems to ‘fit’ at others. Lots of scope for experimentation here. In particular where controlling the pitch and volume of Osc1 with envelopes should open the door to plucks and various weirdness. Next time….

For now, back to our bass. We could apply a little feedback to beef-up the sound. As you have probably already discovered yourself, velocity-sensitive sounds with feedback can give some loud and potentially damaging surprises if a pad is hit too hard. So for setting Amp feedback I first switch-on ‘Fixed’ level’ for the pad. In this way I know I am hearing the maximum feedback level at all times and thus it can be set more precisely. Usually just a small amount is sufficient.



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