Stompbox aficionados will know all about the JRC4558 chip/ integrated circuit residing in Electro-Harmonix's latest dirt box, the East River Drive.
It's found at the heart of some classic overdrive pedals: the Ibanez TS-808 Tube Screamer being the prime example. EHX apparently had lots of requests for a pedal based around a JRC4558, so the East River Drive has been designed to fill that gap. Like the Tube Screamer, the pedal also uses symmetrical clipping.
The ERD can operate as a boost with drive at a minimum; the tone knob dialling in extra top-end presence.
After that, the drive knob brings in a very natural overdrive sound from just breaking up to a medium raunch. So is it a Tube Screamer clone? Well, side by side with our TS-808, we found it very similar in scope, albeit with slightly less of a hump in the midrange.
Whatever its provenance, this is a very natural overdrive for adding some dirt to a clean amp or taking a driven amp to another level.