Ableton Forum

Hi,

I'm new to using Ableton and sound design in general. I've been using Operator a lot and figuring out what all the different knobs are doing. For the life of me, I can't figure out what the envelope in the filter section does.

I thought it would determine the extent to which the filter was applied to the sound -- i.e. a envelope value of '0%' would mean the filter is not applied at all, and '100%' means the filter is applied in full. But changing every ADSR value in the envelope to 0 sounds the same as setting them all to 100.

The filter is turned on and set to a value that does affect the output -- enabling/disabling the filter does have an effect on the sound.

I would greatly appreciate an explanation for why this is happening. Thanks!

The envelope parameter adjusts how much the filter will follow the ADSR curve. If the envelope parameter is at 0%, but you have a low-pass filter engaged at 500 Hz, that's all it will - a static filter that cuts above 500 Hz. I'm going to do my best to explain how it will work in a sort of step-by-step way:

1. Just use one oscillator and choose something rich in frequency content, like a saw wave (Moog D one would be best).
2. Turn on the filter and set it to the lowest point.
3. Go to the filter section and do the following:

- Set the attack to 0 ms.
- Set the Decay to ~ 1-2 seconds.
- Set the Sustain to 0%.
- Set the Envelope to 100%.

4. Hit and hold a note - do you hear what happened? The filter started at the high point of the envelope and filtered out the frequency over whatever length the decay time was set to and ended at the sustain, which at 0%, means it's all the way down to the frequency you set the filter out and thus basically silent. If you move the filter frequency to something like 200 Hz, it will idle there. Alternatively, you can raise the sustain percentage.

From there, you can kind of experiment by changing one parameter at a time. For instance, move the Attack time to 1-2 seconds - assuming the Init parameter is still set to 0 dB - what you'll hear is the filter start at the frequency you have it set to, climb up, and then once it reaches its peak, it will follow the rest of the envelope. You can also use the parameters I laid out and change the envelope to 50% - you'll hear that it has less of an effect.

When I was learning this, it was way easier for me to see it done than trying to understand the concept in writing, so I hope I did an ok job.

This was a perfect explanation -- I totally get it now. The step-by-step example really helped. Thank you!

Peter ~ wrote:This was a perfect explanation -- I totally get it now. The step-by-step example really helped. Thank you!

Good stuff - same basic principles for every other filter envelope on synths, so have fun!