Up for sale, a 1963 Ampeg B-15N Portaflex fliptop amp combo in excellent condition, freshly serviced and loaded with a JBL D140F speaker. The B-15N is one of the most recorded and highly regarded tube bass amp circuits of all time, and this early (third year) example has just been given a clean bill of health from our techs here at Mike and Mike’s Guitar Bar.

As the amp that defined the Motown bass sound and a must-have for studios worldwide, the B-15N is the undisputed king of vintage studio bass tone, with a thumpy sound that is round, detailed, and versatile, bringing out the best in your instrument's natural tonal characteristics. The two channels each have a unique voice, with Channel One being a bit more mellow and smooth, while Channel Two has a touch more grit and bite, also making it an excellent choice for guitar (diming this channel out delivers a particularly nice overdriven roar with a humbucker or P-90 equipped instrument).

The circuit retains the original transformer pair, with a fully recapped power supply and a couple new Sprague caps in the preamp. All but one of the original CTS pots are present, with visible date codes from the 6th week of ‘63. The original plexiglass Ampeg badge is present, illuminating as it should when the amp powers on. The head and cab still connect via the original multi-pin connector, and the amp has been upgraded with a three-prong power cable. The tube complement includes a matched pair of Tung Sol 5881 power tubes, a vintage Westinghouse rectifier, and the original trio of Ampeg by Sylvania 6SL7 preamp tubes.

The speaker is a vintage JBL D140F 15” alnico magnet driver. While Ampeg would include a CTS speaker with the B-15N from the factory (or in some cases an Altec for an upcharge), this JBL is arguably a better option, offering the ideal blend of dynamism, headroom and overall efficiency for a tube-driven bass signal. The original tube chart is intact inside the cab, with the stamped serial number dating to 1963.

This is a well-kept example, with bright chrome plating on the chassis, white silkscreen text, and all of the original knobs present. The original latches are present and the plastic handle for the head tray is MIA. The original blue diamond covering is notably clean throughout, while the trolley is a modern replacement.