A-101-2v

Vactrol Low Pass Gate (Vintage edition)

A Lowpass Gate (LPG) can be a low pass filter, a VCA or a combination of both. This means both the harmonic content and volume can be controlled simultaneously which resembles the behaviour of many instruments: the louder, the more harmonics.

The A-101-2's mode of operation is set with a switch: Left position is low pass, right is VCA and the combo mode is in the center. Alternatively you can activate the modes with gate signals which is the reason for two gate inputs; this is very interesting in combination with clock dividers or trigger sequencers.

Gate 1 high & gate 2 low = Low pass mode
Gate 1 low & gate 2 high = VCA mode
Both Gate 1 & 2 high = Combo mode
The A-101-2 has an aggressive sound, compared to other LPGs and it's resonance goes up to self-oscillation which not many LPGs offer. The oscillation is rather dirty and far from being a sine wave .