Quantum Line Source

About the Quantum Line Source

Introduced in 1976, the Infinity Quantum Line Source QLS-1 is a flagship 4-way, line-source loudspeaker system designed for audiophiles seeking extremely wide bandwidth and high output with low distortion. It uses a vertical array of EMIT (Electro Magnetic Induction Tweeter) units extending high-frequency response to 32 kHz, a line of six 1.5-inch (38 mm) dome midrange drivers operating from 600 Hz to 4 kHz, a dedicated midbass coupler covering 200 to 600 Hz, and a 12-inch (30 cm) Infinity/Watkins dual voice-coil woofer handling bass from 18 to 200 Hz. The full system is a 4-way, nominal 4-ohm design with a rated frequency response of 18 Hz to 32 kHz (+/-2 dB) and crossover frequencies at 200 Hz, 600 Hz, and 4 kHz, and is recommended for amplifiers in the 100-500 W per channel range. Physically, each QLS-1 tower stands about 167-168 cm tall, 38-46 cm wide, and 38-46 cm deep, and weighs roughly 80-90 kg. The front baffle carries multiple EMIT tweeters arranged as a true line source, while at least one EMIT is rear-firing, creating a dipole-like radiation pattern that adds depth and spaciousness to the soundstage. The Quantum Line Source is widely regarded as one of Infinity's most important classic designs, noted for its clarity, powerful and extended bass from the Watkins woofer, expansive imaging, and highly detailed high-frequency performance.