Fender Studio Bass Amp, date this please

From ampwares.com:

Model/Circuit Number:
Years of Production: 1977 – 1980
Era:
Configuration: Combo
Controls: Black Forward facing with white labels
Knobs: Black skirted w/ chrome center, numbered 1 – 10 (EQ knobs numberd -5 to +5)
Faceplate

• Front: Power Sw, Standby Sw, Pilot Lamp – In, In, Vol, Treb, Mid, Bass, Presence – 1850 Hz, 1000 Hz, 390 Hz, 180 Hz, 80 Hz – Output
• Rear: Speaker Jack, ? Jack, Hum Balance Adj, ? Jack, Output Tubes Matching Adj, Fuse (3A)

Cabinet

• Dimensions:
• Hardware:
• Handle: Black Strap Handle
• Feet: Casters
• Corners: Corner Protectors

Covering Material

• Tolex/Tweed: Black Tolex
• Grill Cloth: Black Acoustic Foam with White Trim

Logo: Grill mounted, raised, chrome & black script
Weight:
Speaker

• Size: 1 x 15
• Impedance: 8 ohms
• Model: Electro Voice(For more info, check out the Jensen Replacement Speakers)

Effects: Active EQ
~Watts: 200 watts
Tubes

• Pre amp: 2 x 7025
• Power: 6 x 6L6GC

Bias: Fixed Bias
Rectifier: Solid State

Comments: Active EQ: 12AU7