Krohn-Hite Model 3550 Variable Filter Delay/Echo Here's a quick demo of

Here's a quick demo of another HE-2150 we posted to our Instagram:

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

and has velcro on the base (please see detailed photos below)

And it’s working: was electronically serviced about 2 years ago but there are some mechanical issues (rocker switches

without any low-port noise distortion since all TS subwoofers have a passive radiator

Krohn-Hite Model 3550 Variable Filter Delay/Echo Here's a quick demo ofThe 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.