Premier Guitar

Ampeg B-15N Portaflex

August 17, 2010
Hey Zach,
I’ve got an Ampeg B-15, serial number 0137XX, and I suspect it is from the mid 1960s. Can you tell me a little about my B-15 and what it is worth today? Also, do you know of where I could get a replacement Lucite plate?

Pittsburgh, Pennsylvania

Hey Art,
Ampeg’s B-15 is one of my all-time favorite amps, not only because of its fantastic tone and universal application, but also because of its unique design and versatility. While Ampeg founder Everett Hull didn’t reach the success that Leo Fender achieved, they were two of the most innovative men in the guitar industry between the 1940s and 1960s. Hull created an upright bass pickup by mounting a transducer on an extended peg that was inserted into the body of the bass. Hull received a patent for his amplified peg (Ampeg) design in November 1947 and began manufacturing them in New Jersey with his new partner, Stanley Michael.

Shortly thereafter, Hull and Michael went their separate ways and Hull moved Ampeg to Manhattan where he slowly began building amplifiers and developing the Ampeg name. Ampeg introduced a variety of guitar, bass, and accordion amplifiers throughout the 1950s, and in mid-1956, he hired Jess Oliver, who became Hull’s right-hand man through most of the 1960s and is mainly responsible for designing the Portaflex. Ampeg was always trying to perfect the tone of their amplifiers and Oliver began experimenting with designs such as a double-baffle porting system and a closed-back reflex cabinet. Oliver also borrowed a design from an old sewing machine where the unit would flip out of the cabinet.

The first Portaflex amp was formally introduced in 1960 as the B-15. The double-baffle porting system gave the amp what Hull described as “the creamiest tone.” At the time, combo amps were the norm, with all components housed in a single cabinet, but heat from the electronics often caused the amp to overheat and made the speaker fail. Separate head and speaker cabinet systems, often referred to as piggybacks, became a solution in the early 1960s, but it also negated the portability of the combo. The Portaflex addressed both of these issues, as the electronics were mounted on the top panel that could be flipped over. In transit, the electronic components were flipped down and housed inside the cabinet. For playing, the head was flipped up and exposed. Four latches secured the top to the cabinet and the top was entirely covered so it matched the cabinet regardless of which position it was in. With Ampeg’s Portaflex design, users didn’t have to worry about their amp overheating while they were still able to transport it relatively easily. In fact, Ampeg offered a heavy-duty four-wheel dolly for these amps that became standard equipment on later models.

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.

According to the serial number 0137XX, your amp was built in 1965, which would make it either a B-15NC or B-15NF. Your B-15N has either a 25-watt (B-15NC) or 30-watt output (B-15NF), one 15" speaker, a six-tube chassis with two 6L6 power tubes, and two channels with three inputs and Volume, Treble, and Bass controls for each channel. One of the coolest features of the B-15N was the Lucite Ampeg panel that illuminated when the amp was turned on. This panel sat in the middle of the head and it could be custom ordered with the user’s name engraved on it.

There are a few things to note about Ampeg production from this time. Hull was not a fan of rock ’n’ roll music and never designed an amp for this genre. Therefore, power ratings were very conservative and Ampeg discouraged users from increasing volume to the point where they distorted. In fact, most amplifiers had accordion inputs throughout the 1960s, and Ampeg amps were never really marketed to rock players until Hull left the company in 1968. Ampeg went through numerous ownership changes over the next two decades with Unimusic taking over in 1967, Magnavox in 1971, and MTI in 1980.

St. Louis Music bought Ampeg in 1985 and finally returned some stability and respect to the brand. The company also reissued the B-15N Portaflex with blue check covering in 1995. Ampeg was purchased by LOUD Technologies in 2005, and in 2010, they introduced the new Heritage Series that is produced in the US.

The B-15N has held relatively steady in the used market and is currently worth between $1200 and $1500 in working condition. Gregg Hopkins of Vintage-Amp Restoration reproduces these Lucite plates for the B-15 and can even personalize it with your name. Given its cool features and history, the Ampeg B-15 is definitely treasure.

Source: Ampeg—The Story Behind the Sound by Gregg Hopkins and Bill Moore.

Zachary R. Fjestad
Zachary is the author of the Blue Book of Acoustic Guitars, Blue Book of Electric Guitars, and the Blue Book of Guitar Amplifiers.
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