Altec Model 604-8G is a legendary 15-inch two-way coaxial (Duplex) studio monitor loudspeaker introduced by Altec Lansing in the 1970s. It features an 8-ohm impedance, a 30 Hz free-air resonance, and a high sensitivity of 100 dB SPL, making it a staple of professional recording and broadcast studios.
Design and Specifications
Coaxial Configuration: Combines a 15-inch low-frequency woofer and a high-frequency multicellular/horn tweeter into a single unified frame, allowing point-source sound reproduction.
Frequency Response: Uniformly rated from 20 Hz to 20,000 Hz.
Impedance: Nominal 8 ohms.
Sensitivity: 100 dB SPL (measured at 4 feet with a 1-watt input).
Crossover Frequency: Typically around 1.5 kHz, routing signals cleanly between the large cone and the horn driver.
Enclosures and Integration
Cabinet Size: Often housed in large utility or fine furniture enclosures like the Altec 620 cabinet (roughly 9 cubic feet) to optimize low-frequency performance and tune down into the 30 Hz range.
Modern Updates: Audiophiles frequently pair vintage 604-8G drivers with custom passive crossovers or modern active DSP amplification (such as MiniDSP or Hypex plate amps) to maximize headroom, time-alignment, and room response correction.
