The Rikstone C50 is an AB class combo amplifier with fixed bias. 
The amplifier part is based on the VOX AC50. 

Technical data:

Inputs: 2 x Normal and 2 x Brilliant
Output: 8 Ohm
Controls: GAIN, BASS, TREBLE (Normal channel)
GAIN, BASS, TREBLE (Brilliant channel)
MASTER VOLUME (common)
Tubes: 4 x 12AX7, 2 x EL34
PT: 230V/360V/250mA/6,3V/4,3A
OT: A transformer for EL34 pair
Rectifier: Diode bridge
Speaker: 2 x 12" Eminence Guitar Legend
Schematics: PowerSupply
PreAmp
PowerAmp