I recall my brother buying it on mark-down and that Radio Shack had purchased the excess inventory from Panasonic. It was never in the catalog to my knowledge.
Now I see one listed in the Europe for 600 Euros. My how things have changed.
This amp and I have a history - I grew up with it - and recall hearing Derek and the Dominoes Layla on it for the very first time.
I also listened to the news reports in Dallas about the goings on in upstate New York at the Woodstock Music Festival.
There's not much published on the web about this interesting technology and unit from the 1960s in which Panasonic used electro-mechanical feedback from the low frequency driver.
The original manual and schematic were printed with a brown ink giving them a historical look even then.The MF-800 is a newly developed speaker-amplifier combination which uniquely utilizes a new variable ACCELERATION-VELOCITY type motional feedback system. This system features adjustable damping and frequency response in the low frequency range of the speaker by using a differential circuit in the feedback loop.
Panasonic MF-800 Motional Feedback System Amp and Speakers circa 1968.
Panasonic MF-800 Motional Feedback System Feedback Loops
Panasonic MF-800 Motional Feedback System Schematic
Panasonic Model MF-800 Motional Feedback Amplifier with EASB-8M2 Speakers (10MB pdf): http://www.waynekirkwood.com/images/pdf ... Manual.pdf
Update: Apparently Panasonic licensed the Luxman Motional Feedback patent used in the 1962-era Luxman SQ-65.
The Panasonic amp was also called the SA-30 and also known as the National SA-30.