Yamaha KS-SW100 Keyboard Amplifier

Yamaha KS-SW100 Subwoofer — Deep, Clean Bass for Arranger Keyboards

This purpose-built compact subwoofer was designed to extend the low-frequency response of arranger and stage keyboards from Yamaha. Where built-in keyboard speakers run out of depth on bass-heavy styles, this dedicated sub lets the keyboard's main drivers focus on mids and highs. The result is a fuller, more balanced performance at home or in small venues.

Inside the cabinet sits a 20 cm (8") cone driver powered by 100 W of dynamic amplification, reaching down to 28 Hz. The manufacturer pairs that hardware with two proprietary bass technologies to keep the low end tight. For keyboardists who feel their PSR or arranger setup is missing weight, this sub is the targeted solution.

Yamaha-Only Bass Technologies Inside a Compact Cabinet

What separates this subwoofer from generic home-theater units is two proprietary technologies normally reserved for higher-end audio products. The Twisted Flare Port uses a flared, gently twisting shape to diffuse the air vortex at the port edge, eliminating the chuffing noise that plagues small bass-reflex designs. Combined with Advanced YST II, which dynamically optimizes effective speaker impedance through ANIC circuits, the cone stays under tight control even during demanding bass passages.

Specs That Translate Into Real Low-End Weight

The numbers on the spec sheet matter because they directly determine how the sub behaves in a real keyboard rig. Higher dynamic power means more headroom for transients, while a wider frequency response ensures the sub reaches the deepest fundamentals of synth basses and kick samples.

• Driver: 20 cm (8") cone — large enough to move serious air while keeping the cabinet compact enough for tabletop or floor placement beside a keyboard stand.
• Dynamic power of 100 W at 5 ohms provides the headroom needed for punchy bass transients without compression at performance volume.
• Frequency Response: 28–200 Hz — reaches the deepest audible fundamentals and hands off cleanly to the keyboard's main speakers above 200 Hz.
• Bass Reflex Port: Twisted Flare Port (Yamaha proprietary) — reduces port turbulence for cleaner, tighter low-frequency reproduction.
• Advanced YST II: Yes — servo-controlled cone movement for stable, accurate low-range response.
• Line Input: 1 (single connection) — plug straight into the keyboard's subwoofer or line output without extra adapters.
• Dimensions (W x H x D): 291 x 292 x 341 mm — fits easily beside a keyboard stand or under a desk.
• Weight: 8.5 kg — light enough to reposition between rehearsal room and stage.

Built for Arranger and Stage Keyboard Players

This instrument is the right choice for keyboard players who own a compatible PSR or arranger model and want the low-end weight their built-in speakers can't deliver. It is officially compatible with the PSR-A5000, PSR-SX900, PSR-SX700, PSR-SX600, PSR-E473, PSR-EW425, PSR-A3000, PSR-S975, PSR-S970, PSR-S775, PSR-S770, PSR-S670, and PSR-EW410.

Home players will appreciate how the sub transforms practice sessions, giving drum loops and bass styles the physical impact they lack on small built-in drivers. Live performers in small venues benefit from the 100 W dynamic power, which keeps bass lines audible without overpowering the main mix.