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Grandmother envelope question: just me?
MUFF WIGGLER Forum Index -> General Gear  
Author Grandmother envelope question: just me?
Hi Everyone,

There's something strange about my Moog Grandmother envelope & I'm wondering if others have found the same thing. It seems that when the sustain is set at 100%, it isn't possible to have a zero attack and decay. Whatever I use it to control (internal to the Grandmother, or external), there's always a moderate attack and medium-quick decay even with those controls set to zero. If I dial the sustain back to about 75%, this effect mostly goes away and the controls behave as expected, but I can't do simple ASR anymore.

Have other people found similar things with their Grandmothers? If so, is there a workaround that I'm missing? I do have an email correspondence going with Moog support, but they haven't said anything substantial yet so I thought I'd ask here as well. Thanks...
I don't have a Grandmother to test with, but some envelopes can drive with high sustain which would perhaps push it above level expectations and then you'd get this effect. I have only read about that, not experienced it.

What happens if you back the sustain off a few degrees at a time? Is there a point where you have apparent unity gain without an A/D envelope shape?

Great question-- really excited to know more about this!
I just put in mine on the oscilloscope after reading this. What I found was that neither the attack nor the release curves depend on the sustain position. Naturally the release is shorter from a lower sustain voltage as there is less voltage to "release from". But it always follows the same exponentialish curve. Interestingly the decay seems to exponentially decay to the sustain value at a rate proportional to the difference between the peak and the sustain voltage. Which means the time it takes to decay to sustain is roughly constant and the initial rate depends on the sustain voltage.

Also attack and decay are significantly faster than release. My scope gives me (to or from peak voltage):

    Attack: 1.5ms
    Decay: 1.9ms
    Release: 36ms

Attack is linearish while decay and release are exponentialish
Thanks for the replies. On mine, the behaviour is normal unless I have it set to zero attack, zero decay, full sustain, zero release. From that position, there is about a 500ms attack, and about a 100ms release. I tried luketeaford's idea, but it didn't help much. If I leave things set as above, and then set the sustain to about 80%, the attack goes away (i.e., starts to match the setting of zero on the knob). But if I then turn the attack knob up, the attack comes in but the envelope also respects the lower sustain level, so I can't do simple ASR without the drop at the decay phase.

P.S. I'm testing all this with filter self-resonance as the only sound source, and a bit of envelope applied to the filter. But I also tried it using the Grandmother envelope to the exponential FM on my DPO, with the same results. So whatever's happening is definitely with the envelope signal rather than being some aspect of the Grandmother filter response.

In any event, maybe Moog will have something to suggest...
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