Invisible Series
AT | ST Series
ST21
ST21
Subterranean
The ST21-4 is a 21" subterranean subwoofer designed for high SPL bass output in outdoor environments. It features a powerful 21" transducer, optimized for maximum excursion and SPL, delivering exceptional low-end performance for outdoor audio applications.
Key Features
- All-copper toroidal transformer (70V models)
- Direct burial, compression bandpass subwoofer design
- Marine grade
- Available in a selection of standard or custom colors
- TAA Compliant
Specifications
SKU | Color
ST21
Speaker Woofer
(1) 21" (534mm) Aluminum
Frequency Response (+/- 3db)
18Hz - 120Hz
Sensitivity
91dB (2.83V/1m)
Enclosure
Aluminum
Nominal Impedance (Ohms)
4 Ohms
Dimensions (WxHxD)
24.0" x 24.0" x 24.0" (609.6mm x 609.6mm x 609.6mm)