The YST-SW315 delivers high power at deep bass frequencies, with excellent stability and low power consumption. This is made possible by the sub's highly efficient PWM (pulse-wave modulation) digital-drive power amplifier. The amplifier achieves superior conversion efficiency by minimizing power loss from the power transistors. It delivers stable audio power while minimizing AC power consumption and heat production. As it requires no output filter coil, it's extremely quiet with low distortion.
Yamaha's patented Advanced Active Servo Technology (Advanced YST) generates incredible bass from small speaker enclosures. This system uses negative-impedance feedback in the amp and a Helmholtz resonator in the speaker to provide strong and accurate bass.
QD-Bass (Quatre Dispersion Bass) technology uses a down-firing driver with square, pyramid-shaped reflective plates to radiate sound efficiently in four horizontal directions. The reflective plates (not used in other brands' down-firing subwoofers) negate any effects caused by the floor surface and reduce resonance between sound waves reflected from the floor and the unit. Most other systems use circular cones, but the YST-SW315 avoids firing sound into the legs of the cabinet by radiating in four directions. Changing the height of the pyramid varies the acoustic load, permitting relatively simple high-cut adjustment and improving bandpass properties. QD-Bass also grants greater freedom of placement, since the sound radiates with equal effectiveness in all directions.
The user-adjustable, continuously variable high-cut filter sets the highest frequency the subwoofer will deliver. It can be set anywhere from 40 to 140 Hz. For instance, if the filter is set at 75 Hz, only frequencies 75 Hz or below will be delivered by the subwoofer. This allows the sub's output to be matched to the lowest reproducible frequency of other speakers in the system and the room's acoustics for a seamless presentation.
The rotary volume control permits the perfect matching of the sub's output to the overall volume of the system. The YST-SW315 has a signal-sensing circuit. When the subwoofer detects an audio signal, it turns its power on. When it senses no signal for several minutes, it shuts itself off.
Yamaha's BASS (Bass Action Selector Switch) tailors the sub's output for video or music at the touch of a switch. Two sets of inputs let the sub accept either line- or speaker-level inputs, while a handy phase normal/reverse switch makes it easy to phase the subwoofer with the other speakers in your system.
Three-way speaker terminals accept banana plug and a variety of other connectors, as well as speaker wire, and the YST-SW315's thick, rigid MDF cabinet reduces vibrations and resonance. The speaker's handsome black-ash finish blends in with room decor and complements many furnishing styles, and it's magnetically shielded so you can place it near a TV or computer monitor without degrading the picture.
What's in the Box
Subwoofer, user's manual, and warranty information.