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The Roland TR-03 has an 'Envelope' Parameter. I know many different kinds of Envelopes exist which are made to adjust different parameters:

  • Amplitude
  • Pitch
  • Low-/High-Pass Filter
  • ...

Question 1: What kind of 'Envelope' is it in the TR-03?

At second, a classic envelope has 4 Phases: Attack, Decay, Sustain and Release (ADSR). Other Machines provide 4 knobs to adjust these 4 Phases. One for each Phase. But on the TR-03 there is only 1 knob for the Envelope.

Question 2: What does the Envelope knob do on the TR-03?

Owner´s Manual is located here, but it doesn´t answer my questions: https://www.roland.com/global/support/by_product/tb-03/owners_manuals/

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    Actually, a classic (as in from the 70s) envelope usually is not a fully ADSR envelope. Most of the older synths have simpler envelope generators and/or controls. For example, the Minimoog Model D has just attack, sustain, and decay controls. The decay time and release time are the same, unless release is turned off entirely.
    – Todd Wilcox
    Jun 27 '18 at 11:42
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It's a re-creation of the original TB-303. There are two envelope generators, but only one of them is connected to the control you are asking about. The envelope knob controls the amount of the filter envelope that is sent to the filter cutoff frequency.

The attack time of the filter envelope is fixed. I haven't found exactly what it is, but one place suggested it might be 3ms.

The decay time of the filter envelope is controlled by the Decay knob, but the knob is partially bypassed on accent steps.

The Envelope knob controls how wide the filter sweep is. At least on the original 303, even if you turned the knob all the way down, there was still a bit of filter sweep. Accented steps are also affected differently by the Envelope knob, in that there is a boost to the maximum cutoff frequency of the envelope, helping to make the accent steps sound louder.

This page has a great analysis: http://www.firstpr.com.au/rwi/dfish/303-unique.html

Quoting:

For both normal and accented notes, the [filter] EG affects the filter frequency via the [Envelope] pot. However the circuitry does not allow this effect to be turned down to zero even when the pot is fully anti-clockwise.

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  • Thank you very much for your detailled answer. Perhaps could you draw an image with an x/y-Axis that contains the sweep and point out what happens with the sweep, when the knob will be turned left/right? That would help me (and the community) to understand it easier.
    – Simon
    Jun 28 '18 at 8:49
  • @Simon The envelope knob controls the height of the graph. That's it.
    – Todd Wilcox
    Jun 28 '18 at 13:06
  • I have added an image to you answer. Can you please review if it is correct?
    – Simon
    Jun 29 '18 at 6:30
  • @Simon It’s very misleading as to the actual shape of the envelope.
    – Todd Wilcox
    Jun 29 '18 at 13:22

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