Dual 21" Subwoofer

Large format Dual 21" Touring subwoofer with truly professional finish, materials equivalent size and cost to conventional dual 18", with 50% more output power and fast accurate response even at high crossovers, for any touring or high SPL or infra extension subwoofer application.


The goal of BASSO2121 is to bring that world-class touring subwoofer performance in a package equivalent in size, weight and set-up requirements to most standard dual 18″ subwoofers available in the market today, providing tour sound companies with a cost-effective solution for professional touring set-ups and top subwoofer performance for sound productions and installations of any size, complexity and budget.
BASSO2121 mounts IDEA 21″ woofers, with 4″ dual voice coils, 1600 W power and superlative mechanical and thermal specifications housed in two separated chambers within the enclosure closed by 8 radial large bass-reflex ports. This construction allows a direct radiating bass reflex (with less phase alignment issues when working with line array systems) and the back-pressure inside each woofer chamber to be discharged through the ports symmetrically from the axis of the voice coil and the woofer chassis. This keeps the cone excursion linear, reducing distortion, power compression and improving tone definition at the crossover point and long term reliability. But just as importantly, with this positioning and assembly, the ports become part of the structural reinforcement of the cabinet required to withstand the massive air pressure changes and the mechanical stress while keeping the total size relatively compact.
Like All Idea Loudspeakers BASSO2121 is built with the necessary structural strength and finish quality required for durable touring use. The high quality 18 mm birch plywood enclosure coated with Idea custom paint solution and a 2 mm steel front grille will keep your equipment safe and brand new after hours of heavy touring.


  • Compact Dual 21″ Direct Radiations design
  • Rugged and durable 18 mm birch plywood construction and finish
  • Premium European High Efficiency custom IDEA Transducers
  • 4 Ohm Passive
  • Dual Neutrik NL4 connectors
  • Durable Aquaforce paint, available in standard textured black or white, optional RAL colors (on demand)
  • 36 mm pole cup and four integrated handles


  • Main system for Regional Touring and Rental Companies
  • FOH for high SPL venues and clubs
Enclosure design Bass Reflex
Transducers 2 × 21”
Power Handling (RMS) 3.2 kW
Nominal Impedance 4 Ω
SPL (Continuous/Peak) 136/142 dB SPL
Frequency Range (-10 dB) 20 – 80/95/120 Hz
Frequency Range (-3 dB) 24 – 60/75/100 Hz
Dimensions (W×H×D) 1200 × 600 × 950 mm
Weight 129.5 kg
2 × Neutrik speakOn NL-4 in parallel
Parallel signal
Cabinet Construction 18 mm Plywood
Grille 2 mm perforated weatherised steel with protective foam
Finish Durable IDEA proprietary Aquaforce paint coating process
Handles 4 integrated handles
Feet/Skates 4 skates (H/V)
Installation 36 mm Pole mount socket
Accessories 35 mm Pole (P-21336)
Casters (WH-04)

* Specifications may be subject to change without notice.


Spare Parts

  • S21-41-8 | Woofer 21″
  • R-S21-41-8 | Membrane for woofer 21″