Ampeg Portaflex

B-15N

The Portaflex is a line of amplifiers for electric guitars and bass guitars created by Ampeg. Originally designed by Jess Oliver, the main characteristic of the Portaflex is that the head of the amplifier is stored inside the cabinet and flips over when being used. The Portaflex line has many different configurations.

SB-12

Ampeg manufactured the Portaflex SB-12 model amplifier from 1965-1971. This lightweight (67 pound) cabinet incorporated the flip-top design of other larger Portaflex amplifiers of the time. Although the SB-12 isn't as well known as the more powerful B-15, it is still highly sought after by musicians who use it mainly for studio recording.

The 'SB' in SB-12 stood for string bass; the '12' indicates the diameter of the speaker in inches. It contained a single-channel, 25-watt tube amplifier and a single Jensen speaker. Unlike bulk of the Portaflex line of bass amplifiers, the SB-12 was designed as a universal amplifier. It incorporated two separate inputs, one labeled "Bass" and the other "Instruments".

Gallery

• 
  Portaflex B-15N (1960s)
• 
  BT-15 (1966/1967-?) transistor amp head
• 
  Portaflex B-15N (1970s)
• 
  Portaflex PF-350 class-D amp head

References

• Zachary Fjestad (August 17, 2010). "Ampeg B-15N Portaflex". Premier Guitar. Much like all of Ampeg's amps, the B-15 underwent constant change, and the B-15 was replaced by the B-15N in 1961. In 1962, Ampeg updated the B-15N with a solid-state rectifier called the B-15NB and introduced their famous "blue check" vinyl covering to their entire amp line. Ampeg went back to a tube rectifier and changed to a printed circuit board in 1964 (B-15NC). This model lasted until mid 1965, when they introduced the B-15NF with fixed bias tubes and a single-baffle cabinet. (see Ampeg B-15-N image)
• Gregg Hopkins; Bill Moore. "Solid-State in the Garden State". Ampeg: The Story Behind the Sound. Musical Instruments Series. Hal Leonard Corporation, 1999, 288pp. p. 118. ISBN 9780793579518. At the 1966 summer NAMM show, Ampeg displayed a line of solid-state amplifier. ... they were officially offered in a separate catalog in 1967. Seven models were listed, all of them two-channel Portaflex amps with volume, treble, and bass controls for each channel. These amps also featured an "electroluminescent" control panel, which would glow, without using light bulbes, to backlight the controls. ... {{cite book}}: Cite has empty unknown parameter: |1= (help)
• Clint Stiles (stiles72). "Ampeg BT-15C" (photo gallery). photobucket.com.{{cite web}}: CS1 maint: numeric names: authors list (link)
• "Ampeg: Portaflex Series - PF-350". Ampeg. RMS power output: 350W @ 4 ohms / Preamp: Solid-state / Power amp: Class D

Further reading

• Pagán, Eduardo Obregón, "Motown Amp", History Detectives, PBS. July 25, 2012