What tubes does the Ampeg SB-12 Portaflex - Normal use?

The Ampeg SB-12 Portaflex - Normal uses 2× 6EU7 preamp tubes and 2× 6V6GT power tubes.

When was the Ampeg SB-12 Portaflex - Normal produced?

The Ampeg SB-12 Portaflex - Normal was produced 1959–1971.

Ampeg SB-12 Portaflex - Normal preset

Verified · 83/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The Ampeg SB-12 Portaflex was a compact tube bass amplifier introduced around 1959, featuring the iconic flip-top design where the amp chassis pivots into the sealed cabinet for easy transport. It produced approximately 15 watts from a pair of 6EU7 and 6V6 tubes, driving a single 12-inch speaker in an acoustically tuned cabinet. The SB-12 was specifically engineered for upright and electric bass, offering the punchy, focused low-end that defined Ampeg's bass amplification legacy.

Years produced: 1959–1971
Made in: USA
Wattage: 15W
Channels: 1
Preamp tubes: 2× 6EU7
Power tubes: 2× 6V6GT

Tags: american.

Schematic-derived preset files for 16 Fractal and Line 6 modelers: Axe-Fx II/XL/XL+, Axe-Fx III, FM3, FM9, and the full Helix family (Floor, LT, Rack, HX Stomp, HX Stomp XL, Native).

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