Krohn-Hite Model 3550 Variable Filter Delay/Echo It had suffered the usual

It had suffered the usual battery damage - this has been repaired and a new battery fitted

Input is on a mini-jack socket

manual and PSU

Use both knobs with both hands and create your own filter effect

The top edge have some paint damage and have been re-painted in black

Krohn-Hite Model 3550 Variable Filter Delay/Echo It had suffered the usualThe Krohn Hite 3550 Variable Filter is a multifunction filter that offers band pass, band reject, low pass or high pass operation in a single piece of equipment. The mode of operation can be selected by a front panel switch. The cut off frequency is continuously adjustable from 2 Hz to 200 kHz.