A 3-way/4-drivers active pair o' boxes of the... rare kind.
From Revox's last actively successful period, made to be powered by the B252 version of the B251 integrated amp or used in passive mode with the B251. Probably as expensive as a new 300SL motor, this, however, was Revox's small set !
Powered by 3 separate 100W amps, with the two bass drivers working with a resonator and the bass power amp compensating for the impedance variations of the moving coils.
The mid driver is the main man, spreading its response over 4 octaves and accompanied by an eddy-current magnet system correcting for distortion. The high driver is made of Titanium.
I believe the "bass blend" knob is to change the slopes of the network.
Has anyone ever used these ?