Here is what Mike says…

’This model of Roberts radio was made between 1969 - 1977.

It's now fitted with a new hand wired amp circuit based on the classic Ruby Amp by Runoffgroove.

Features original Volume-On/Off switch, tone control and Rola speaker.

Powered by internal 9v battery or external 9v standard pedal power type supply (centre negative, sleeve positive).

This amp gives you a wonderful vintage sound and character that makes modern amps sound soulless in comparison.‘