The Pioneer SE-50 was a two way design manufactured by Pioneer from 1969 to 1972. It incorporated a 1-9/16" tweeter for highs, and a 3" woofer for lows. The tweeters are controlled by two knobs on one side of each ear cup. The headphones also offered independent volume control of each ear cup for optimum balance of sound. This was controlled by knobs on the opposite side of the ear cups as the tweeter controls.