The Funktion One 21SW152-8 is a 21-inch subwoofer built for high-output low-frequency reinforcement in professional systems. Key figures to keep on file: 2000 W power handling, 30–120 Hz frequency range, 136 dB max SPL, 8 ohms impedance, Speakon NL4 connector and input, 760 × 580 × 580 mm dimensions and 68 kg weight. For distributors and rental companies, these numbers define amplifier pairing, cabinet logistics and truck-pack planning more than any marketing claim, so confirm them against the unit in front of you rather than a listing alone.
Condition grade A on a used subwoofer should mean the cabinet is structurally sound and cosmetically clean for its age, with no soft corners, no separation at the joints and no evidence of water ingress. Inspect the driver cone and surround for tears, creasing or re-coning marks, check the grille and mounting hardware, and look closely at the Speakon NL4 panel for cracked plastic or loose pins. Because the 21SW152-8 is a heavy 68 kg box, also check the handles, feet and any rigging or stacking points for stress cracks. Distributors who also stock smaller boxes can apply the same inspection routine to our used JBL EON1500 buying guide before requesting test reports.
Ask for a test report before committing. The listing states tested on request, so request a sweep across the 30–120 Hz band at moderate level and listen for voice-coil rub, chuffing or mechanical noise that a quick tap test will not reveal. Confirm the impedance reads close to 8 ohms on a meter and that both NL4 pins are wired correctly. For rental fleets, a short bench check of every unit is cheaper than a failure in the field. Planners building a festival subwoofer system design around the 21SW152-8 should match cabinet counts and amplifier channels to the 2000 W, 8 ohm rating before finalising the truck pack. Distributors weighing this cabinet against other high-output options can compare inspection criteria in our used K Array RedLine subwoofer buying guide before requesting test reports. Buyers comparing output options should ask for a bench test report on the used K Array RedLine 12 subwoofer just as they would for the 21SW152-8.
For overseas distributors and system integrators, plan shipping around the real 68 kg per cabinet and the 760 × 580 × 580 mm footprint; pallet counts and freight class follow from those figures, not from guesses. Confirm amplifier compatibility for 2000 W handling and 8 ohms before you quote a package, and state clearly whether the price is FOB or otherwise. Venue owners buying single units should confirm the sub matches their existing processor presets and crossover settings. For nightclub subwoofer installation, venue owners should confirm the 760 × 580 × 580 mm footprint fits the intended floor or stage position and that processor presets match the existing system. Rental companies needing a lighter dual-driver alternative can review the used JBL SRX828S dual 18 subwoofer as a complementary cabinet for smaller rooms. Rental companies sourcing cabinets alongside amps and processors can browse our second hand pro audio gear for matching system components.
Finally, treat grade A as a starting point, not a warranty. Ask for photos of the driver, the connector panel and the cabinet edges, and get the test result in writing. OxGears lists the Funktion One 21SW152-8 with tested-on-request status, so build that check into your purchase approval rather than assuming it. Clear condition notes and a documented bench test protect both sides of a B2B deal. Operators fitting a nightclub bar PA system should confirm the 21SW152-8 footprint and processor presets against the room before ordering multiple cabinets. Studios kitting out a control room alongside the PA purchase can also review used Barefoot MicroMain27 monitors for reference monitoring.
Questions about this unit or about shipping to your country? Contact us for condition photos, test results and a quote. Integrators matching amplification to a subwoofer package should confirm compatibility on the used Barefoot Sound amplifier before quoting a full system.
Questions about this unit or about shipping to your country? Contact us for condition photos, test results and a quote.
The Funktion One 21SW152-8 is a high-performance 21-inch professional subwoofer driver featuring a rugged cast-aluminum basket and high-power magnetic circuit design, suitable for large-scale live events, nightclubs, and fixed installation systems. The unit is clean in appearance, with an intact grille, and has passed functional testing.
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