Altec built in the wall... once you got used to them, you knew exactly what you had in your mix. They are very comfortable to listen to for long hours.

The 604E is extremely well built and is undoubtedly one of the best constructed and designed compact speaker systems of all time. The original version was introduced in 1941 and it remained in production until the late 90’s, with improvements and modifications along the way.
It was an extremely popular driver for critical monitoring applications. It provided stunningly clear and in-phase sound reproduction. From the 1950's through the 1970's, the various Altec Duplex models were used by more recording and broadcast studios then all other monitor systems combined.
Even in today’s ever expanding market of professional monitors many sound engineers and artist prefer the tried and true sound of the legendary Altec Duplex system.
When mounted in an appropriate enclosure it is an absolute marvel that transcends the limits of what you normally expect from a vintage or modern speaker system. The full range drivers operate in complete harmony, together providing a single point source covering the whole acoustic audio spectrum in a way that recreates the original sound field better than any other system.
Because the high frequency driver is concentrically mounted in the woofer, perfectly aligned both mechanically and electro-acoustically, frequency response and phase response is not affected by nodal-cancellation as found in every normal multi-way speaker system.
Music is depicted with tremendous detail and depth; you hear things on the recording that you never before heard. Voice and instrument are utterly natural. The bass is tight, clean, and thoroughly musical; it dips down to amazing depths.
The highs are smooth and sweet with extreme clarity revealing even tiny details at low volumes; music sounds balanced and articulate. Regardless of what music genre you like the 604E Super Duplex will deliver it accurately.


Power: 35 watts (50 watts, peak)
Frequency Response: 20-20,000 Hz
Pressure Sensitivity: 101dB SPL at 4 ft. from 1 watt* or 116.4 dB SPL at 4 ft. from 35 watts
Impedance: Designed to operate from 8 to16 ohms
Normal LF Cone Resonance: 25 Hz
Voice Coil Diameters: LF: 3 inches
HF: 1 3/4 inches
Horizontal Distribution: 90°
Vertical Distribution: 40°
Magnet Type: Alnico V
Magnet Weight: LF: 4.4 lbs
HF: 1.2 lbs.
Magnet Structure Weight: LF: 20.31 lbs
HF: 6.5 lbs
Flux: LF: 13,000 Gauss

Altec crossover

HF: 15,500 Gauss
Crossover Network : 1,500 Hz dual full section
Terminals: binding posts (4)
Diameter: 15 5/16 inches
Mounting Data: Baffle opening: 13 1/4 inches
Mtg. Bolt Centers: 14 3/8 inches (8 equally spaced at
Depth: 11 1/8 inches
Weight: Drivers: 32 lbs each
Crossovers: 2 lbs each