Altec 604E Super Duplex
1964 - 1973
The 604E Super Duplex continued the legacy of the world's most famous coaxial speaker. Introduced as an improvement over the short-lived 604D and the 605A, the 604E restored the classic 604 formula while incorporating several technical refinements.
Specifications
| Type | 2-way coaxial loudspeaker (Duplex) |
|---|---|
| Low Frequency Driver | 15" cone with 3" voice coil |
| High Frequency Driver | 416-8A compression driver with 1.75" diaphragm |
| Horn | Sectoral horn with vanes (40° x 90° dispersion) |
| Crossover Frequency | 1,500 Hz |
| Nominal Impedance | 8 Ω or 16 Ω (604E-8, 604E-16) |
| Power Handling | 50W continuous |
| Sensitivity | 98 dB/W/m |
| Frequency Response | 30 Hz - 20 kHz |
| Magnet Structure | Alnico V |
| Weight | Approximately 45 lbs |
Design Improvements
The 604E addressed several issues that had emerged with the 605A, which was poorly received by the market. Key improvements included:
- Restored Full Magnet Structure: The 604E returned to the full Alnico V magnet assembly that the 605A had reduced
- Improved Suspension: Updated woofer surround for better linearity
- Enhanced HF Section: Refined compression driver and phase plug design
- Consistent Manufacturing: Tighter quality control than previous versions
The "Super Duplex" Name
The "Super Duplex" designation emphasized the speaker's professional-grade capabilities. Unlike earlier 604 versions, the E was marketed explicitly to both professional studios and serious home listeners who wanted the same equipment used in recording facilities.
Available Impedances
- 604E-8: 8-ohm version for consumer and professional use
- 604E-16: 16-ohm version for professional installations (allowed easier parallel wiring)
Recommended Crossovers
The 604E required an external crossover. Altec recommended:
- N-1601: Original crossover network
- N-1601-A: Updated version with improved components
- N-3000-E: Later high-power version
Historical Significance
The 604E represents Altec listening to their customers. When the 605A was introduced as a cost-reduced alternative, the market rejected it - customers wanted the full-performance 604 they knew and trusted. The 604E restored that confidence and remained in production until the 604-8G was introduced in 1973.
Many consider the 604E to be the sweet spot in the 604 series - offering classic Alnico magnet construction with the reliability and refinements of 1960s manufacturing.
Related Models
- 604-8G Super Duplex - Successor with further improvements
- 605A Duplex - The intermediate model that the 604E replaced
- 604C Duplex - Earlier version with different horn design