Model D contour generator - is this normal???

[trebmonster]

If I set Attack to zero, Decay to 200ms and Sustain to max, I would expect the contour to immediately hit peak then stay there until I release the key. Instead it reaches peak and decays a bit, say 20% and stays at that level until I release. Compared to a modern ADSR e.g. Voyager, its as if I'm not turning up the S all the way. Is this normal? Thanks

[till]

The original Minimoog envelopes had some "over shooting" at the peak of the attack. But I never measured the levels.