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.