Tempest Recipes: Cowbells

February 21, 2012

I’ve got a fever, and the only prescription is more cowbell… ūüėČ

The 808 cowbell is highly distinctive and surprisingly easy to recreate. Synthesizing it’s basic form provides a launchpad into the realm of Agog√īs, Glockenspiels and other idiophones.

Just to remind ourselves: 808 cowbell

It’s spectrum at peak:

808_Cowbell_Spec

Our basic 808 cowbell recipe is taken directly from the manual for the Waldorf Attack VST Рitself a great drum synth (and synthesis reference).

The TR-808 Cowbell is made of two square oscillators, one oscillating at 540Hz, the other oscillating at 800Hz. The attack phase of the envelope is emphasized heavily to create the strong click. Afterwards, the summed signal is sent through a band pass filter and an envelope that stops abruptly

Tempest easily has these specifications, so we’re in gravy. This is where a spectrum analyzer saves the day,¬†because it helps us to visually tune the oscillators to the required frequencies.

More practically, we can proceed as follows:

  • Start with an¬†square in Osc1 (pulse@50%). Leave wave reset off.
  • Key Follow should also be OFF for this example. Although the end result might be played chromatically, we may prefer to have more control over pitch tracking.
  • Tune it’s fundamental down to 540HZ or thereabouts (D#6). By¬†just¬†listening,¬†you’ll know when your’re in the general vicinity.
  • Now set Osc mix to 0/100, letting only Osc2 to be heard. Similarly, tune it’s square wave to the 800HZ region (G#6, keytracking OFF). Detune them a little.
  • Mixing Osc1 back-in reveals the basic tone you need. We’re almost there already:

Listen: Tempest Cowbell basis

Changing the balance between Osc 1 and Osc 2 gives different flavours, as does pitching both Oscs up and down, alone and together. Notice that the 808 spectrum shows the 800Hz peak as most pronounced.

One ingredient we lack is the perceptible movement in the sound itself. There is some extra chaos that we haven’t quite nailed yet. But then we’re using pulse waves, so we can generate some interest with Pulse Width Modulation (PWM). So…

  • Set LFO1 destination to OSc1/2 Pulsewidth, set rate to about 30 and bring-up the amount. A value of about 30 sounds¬†right¬†to me, but play with it.
  • Change the pulse widths manually in relation to one another.¬†Instead¬†of modulating both pulses, try just one at higher LFO rates/amount.

By now we know we have the 95% of the basic tone, but not the shape.

The Amp envelope is the key setting here. Looking at the 808 waveform is instructive. The sound clearly has a short but significant attack phase before descending into a logarithmic long release.

808vsTempest1_cowbell

As we know from the manual, Tempest’s envelope segments can be re-shaped through modulation.

  • First try setting the Amp envelope decay to 100 so we have a nice long tail to play with. Now in ModPaths we map the Amp Envelope to it’s own decay and apply¬†some¬†positive¬†modulation.¬†This bends our envelope inwards like the picture above. The difference can be subtle, so tweak around and see what’s happening.
  • Increasing Amp attack just a little. It may seem unintuitive, but you can re-shape the transient which can be quite effective sometimes. ¬†Try increasing the Attack slowly upwards and listen for the changes and possibilities. When using several envelopes, varying their attack time just slightly can give really interesting results.

OK then, all very well so far? We haven’t touched the filter yet, and we need it to reduce the brightness

  • Keeping resonance at zero, close down the filter cutoff until the sound is quite muffled, then increase the cutoff envelope amount. Increase the attack slightly to align with the Amp attack, increase the decay and bend it’s envelope segment as we did for the Amp envelope. Also, bring-up the high-pass filter to cut-out the lowest frequencies.

Getting the envelopes right on your bandpass can take¬†some¬†time, but there’s¬†a fair¬†amount¬†of tweaking possibilities from here. You¬†could¬†try:

  • A little Filter FM and/or Amp Feedback provides more beef. The feedback in¬†particular¬†can really fatten the attack, making it sound almost block-like. Modulate these with envelopes.
  • Modulate the highpass filter to make it cut the sound off abruptly (as suggested by waldorf’s description).
  • Drastically altering the pitches in relation to one another and layering-in digital samples.
  • Remember that in¬†initialized¬†patches, the Amp envelope is slightly open already, and the Amp velocity control is on full (127). We probably don’t need such dynamic range here – a cowbell is hardly the most nuanced of instruments. So turn the Amp¬†velocity¬†amount down to about 10 and set the Amp envelope amount up to 100. This makes the sound consistently louder.

Idiophones can and are usually played chromatically, but if we go to 16 Tunings mode, each pad will sound the same. Remember we turned keytracking off? When it’s on it makes sure that each keypress will be one semitone higher or lower than it’s¬†nearest¬†neighbours. ¬†But we¬†can apply our own desired level of keytracking in the ModPaths menu, and not just to pitch. The ModPath source to use is ‘Note Number’. You can now assign your own intervals between keys – a setting of + 127 mapped to pitch corresponds to Keytracking turned on (and thus one¬†semitone¬†intervals). At +64 there is one-half semitone intervals and it’s starting to get weird already.

If you do decide to leave oscillator keytracking on by default, you will need to tune the oscillators differently. For interesting results, try activating Oscillator sync and tracking only one of the oscillators at a time. When in sync, Osc2 defines the pitch of the note.

Whether this is useful to you is moot – the option is there, and¬†should¬†be closely¬†inspected¬†for the¬†sound¬†design possibilities. Personally I feel I’ve only scratched the surface, so from here you’re on your own for cowbell sounds. But I think you’ll be OK. ūüėõ

Finally – do I need to say it? A touch of reverb will really make these sounds shine.

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4 Responses to “Tempest Recipes: Cowbells”

  1. Nic Says:

    Thanks for taking the time to drop some awesome knowledge ;D


  2. Helpful information. Fortunate me I found your site unintentionally, and I am surprised why this twist of fate did not
    took place earlier! I bookmarked it.

  3. Leo Says:

    Found your blog some days ago… The best way to express what i want to say is : I just cant stop reading your Tempest posts.

    Thank you for making it public.


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