Leslie speaker dating
The rotating plate in front of the speaker creates a doppler effect where the frequency is modulated due to redirection of sound waves.
The rotor has two speeds, approx 40Hz (slow) and 340 Hz (fast), which will give either a chorus or a vibrato effect.
Its purpose was to prevent the bass and upper treble from entering the Vibratone.
It doesn’t need bass or upper treble (see speaker chapter below for more information). a Vibrolux Reverb via the crossover filter, the Vibratone get the mids while the main speakers of the Vibrolux Rever gets reduced mids..
The picture below shows a 1964 Fender Vibroverb as the main amp and a 1968 Bandmaster Reverb running the Vibratone.
The Bandmaster Reverb expects a 4 ohm speaker load and we use it with very little reverb, reduced bass and a high treble setting.
The Vibratone consist of a closed back cabinet providing a deep bass response.