The biggest changes to the ACP88 were in the gate circuit. The ACP8 had a fixed attack (gate opening) timing of 50 microseconds and a variable range attenuation knob. On the ACP88 we scrapped the variable range in favor of variable attack time (10 microseconds to 100ms) and put the range attenuation control on a two position switch ( -60dB or -20dB).
The result is a gate that performs better on a variety of applications because of the ability to slow down the opening time. On the back we added a sidechain for the gate instead of just the gate key. This allows for frequency triggered gating by inserting an equalizer.