1970 AMPEG B15-N
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1970 B-15 characteristics: Black painted steel chassis bolted onto the lid, aluminum front control panel with "blueline" silkscreened graphics, two channels with normal and bright input jacks, black plastic tone adjustment rocker switches, round black D shaft knobs with silver tops, CTS potentiometers, black plastic polarity and power switches, small round red power light, two large black transformers, black tube cage protecting the tubes and capacitors, metal standby switch on the back panel left side, fuse, two prong power cord and outlet, serial number stamped into the back of the chassis, white Linden New Jersey logo silkscreened onto the back of the chassis, schematic, vinyl handles on top and sides of speaker cabinet, 4 pin XLR speaker cable and Switchcraft jack, 4 chrome lid latches, vinyl covering, metal "a" bullseye logo positioned on the silver grille cloth, 15 inch CTS speaker, matching dolly with wheels.
Ampeg 1970 serial numbers started around 93000. However, Ampeg serial number dating is undocumented and very difficult. Some examples of 1970 serial numbers are 09405x and 10251x. For more precise dating cross reference the serial number with the amplifier's transformer, potentiometer, capacitor and speaker codes.