Infra-sub large scale subwoofer



Infra-Sub unit with a single 21” long excursion woofer capable of very high electro-acoustic transduction efficiency (excellent integration of the various domains: electrical, mechanical and acoustic).
The world’s most compact and lightweight subwoofer with extremely high SPL (147 dB peak @ 1 m).
Deep, very clean infra-low frequencies (23 Hz), thanks to an impulse response with a very small ripple.
Highly ingenious acoustic design that ensures top performance: a hybrid waveguide indirect radiation system able to completely recover low frequency sound pressure emitted from the rear of the unit’s 21” woofer.
The internally braced cabinet ensures utmost sturdiness, free from harmful sound “colouring” due to resonance; an optional trolley with sturdy smooth-running wheels facilitates transport, even on relatively uneven surfaces
Built to be used alone or in multiples, with the utmost reduction of footprint in relation to output and SPL achieved.


LAB 21 HS is a loudspeaker system suited to high-quality sound reinforcement of infra-low frequencies. It comprises a NdFeB 21” long-excursion woofer magnet (6.5″ voice coil). Loading is a hybrid waveguide indirect radiation system able to completely recover low frequency sound pressure emitted from the rear of its 21” woofer, which means an increase in sensitivity of 6 dB SPL.

In other words, with the same input voltage, this system gives an additional 6 dB over the entire low frequency band compared to the same speaker used in a closed cabinet and, on average, an additional 3 dB compared to what the same speaker would give at low frequencies if used with a horn-loaded, reflex or band-pass system. The fact that the sound is generated by two masses of air moved by a single diaphragm, greatly benefiting attack velocity in the transitory frequencies, results in deep, very clean low frequencies.

Intended as a complete system, the LAB 21 HS ensures very high electro-acoustic transduction efficiency, thanks to its excellent integration of the mechanical and acoustic domains. The coordination of these aspects, along with the dedicated amplifier (Outline T Eleven), enables the maximum energy transfer and output power control fully respecting input signals’ dynamics.

LAB 21 HS has a frequency range at -10 dB of 23 Hz to 165 Hz (maximum crossover frequency suggested: 100 Hz). Among the optionals available, a trolley ensures fast handling and efficient protection of the front of the enclosure against impacts. The black finish is in special high quality wear and weather-resistant paint. Sixteen strategically positioned integral handles facilitate handling.


FREQUENCY RESPONSE (-10 dB) 23 Hz – 165 Hz
AVERAGE DISPERSION Quasi-omnidirectional
IMPEDANCE 4 Ω (min 4.3 Ω)
POWER – WAES 2000 (8000 peak)
MAX SHORT-TERM SPL @ 1 m* 147 dB SPL (half-space)

* calculated using +10 dB crest-factor signal


LOUDSPEAKERS AND LOADING 1 x 21″ NdFeB woofer, hybrid waveguide indirect radiation system
WEIGHT – SINGLE UNIT 125 kg (275.5 lb)
DIMENSIONS (Net) Height: 726 mm (28 19/32″)
Width: 1126 mm (44 11/32″)
Depth: 820 mm (32 9/32″)


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