The Technics 7 was the prototype for the linear-phase series developed to address phase issues in multi-way speakers. The most characteristic feature of the Technics 7 was its unique design based on linear-phase theory. Excellent sound localisation was achieved with flattened sound-pressure frequency response and phase frequency response by arranging the sound source centres of all the units in one straight line as seen from the side, as well as staggering their positions somewhat in the forward and reverse directions in order to provide correction. Also, placing the units as close together as possible along with arranging them vertically in a row achieved excellent directional characteristics. The speaker system included a 35-cm cone woofer for low frequencies and a 12-cm midrange for the midrange frequencies. In addition, a 3.2-cm dome tweeter using a ferrite magnet was employed for the high frequencies. With flat phase characteristics both theoretically and as measured, the Technics 7 greatly influenced later speakers as the world's first linear-phase speaker.