The 715, 815, HL-722, and HL-822 are all deviations of the same “guts” – each model simply bearing a different cabinet. The service manual and parts are the same for all four models.
This model was designed to be used with a combo preamp for portable organs and keyboards. It features both a rotary channel and a full range stationary channel.
It is a Pro-Line “portable” version of the HL-722.
Some specimens appear to have been built with no grill cloth and no silver accents, making it more of a plain Tolex covered box in appearance.