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Detailed specifications for the PSW3500 speaker unit, including frequency response and sensitivity.
Component list for the Switched-Mode Power Supply (SMPS) circuit PCB.
Component list for the Pre-Amplifier and Power Amplifier PCB assemblies.
Detailed schematic diagram of the pre-amplifier section.
Detailed schematic diagram of the power amplifier section.
Detailed schematic diagram of the Switched-Mode Power Supply (SMPS).
Detailed specifications for the PSW3500 speaker unit, including frequency response and sensitivity.
Component list for the Switched-Mode Power Supply (SMPS) circuit PCB.
Component list for the Pre-Amplifier and Power Amplifier PCB assemblies.
Detailed schematic diagram of the pre-amplifier section.
Detailed schematic diagram of the power amplifier section.
Detailed schematic diagram of the Switched-Mode Power Supply (SMPS).
The KEF PSW 3500 is a powered subwoofer designed to enhance the low-frequency audio experience in a home entertainment system. Its primary function is to reproduce deep bass sounds, adding impact and realism to music, movies, and games. The subwoofer is an active system, meaning it has a built-in amplifier specifically matched to its driver for optimal performance.
The core function of the PSW 3500 is to extend the bass response of an audio system beyond what main loudspeakers can typically achieve. It features a closed-box, downward-firing design, which helps to distribute bass evenly throughout a room and can make the subwoofer less sensitive to placement.
The subwoofer incorporates a comprehensive signal processing section, starting with input buffers for both left and right channels, as well as a dedicated LFE (Low-Frequency Effects) input. This allows for flexible integration into various audio setups, whether a stereo system or a multi-channel home theater.
A key feature is its variable low-pass filter, which allows users to adjust the crossover frequency from 40 Hz to 140 Hz. This enables seamless blending with different main speakers, ensuring that the subwoofer only handles the frequencies that the main speakers cannot reproduce effectively. For dedicated home theater applications, a fixed LFE input is provided, bypassing the variable crossover and allowing the AV receiver to manage the bass management.
The PSW 3500 also includes a phase adjustment control, offering a range from 0 to 180 degrees. This feature is crucial for optimizing the subwoofer's integration with other speakers, preventing phase cancellations or reinforcements that could lead to uneven bass response. By adjusting the phase, users can ensure that the subwoofer's output arrives at the listening position in sync with the main speakers.
To further tailor the sound, the subwoofer is equipped with a bass boost function, specifically designed for 40 Hz at +6 dB, and a shelf EQ. These controls allow users to fine-tune the low-frequency output to suit their personal preferences and room acoustics. A 250 Hz low-pass filter and a high-pass filter set at 18 Hz are also part of the signal path, contributing to the overall sound shaping and protection of the driver.
The internal amplifier is designed to deliver substantial power to the subwoofer's long-throw driver. It includes a current amplifier stage and incorporates protection circuits for overcurrent and offset, safeguarding both the amplifier and the speaker from potential damage. A limiting circuit is also present to prevent distortion at high output levels.
Power management is handled by a switched-mode power supply (SMPS), which is known for its efficiency and compact size. The SMPS provides the necessary voltage rails for the amplifier and control circuitry. The subwoofer also features an auto on/off function, allowing it to automatically power on when an audio signal is detected and enter standby mode when no signal is present, contributing to energy efficiency and convenience. Alternatively, a manual on/off switch is available for direct control.
The PSW 3500 is designed for user-friendly operation and integration into various audio environments. Its flexible input options, including left and right channel inputs and a dedicated LFE input, make it adaptable to both two-channel music systems and multi-channel home theater setups. The inclusion of a volume control, along with the variable low-pass filter and phase adjustment, provides comprehensive control over the subwoofer's output and its blend with the main speakers.
The "Music/Cinema" bass boost feature offers a quick way to adjust the bass character to suit different content. For music listening, a more subtle bass enhancement might be preferred, while for action-packed movies, a more pronounced boost can add to the cinematic experience.
The LED display provides visual feedback on the subwoofer's operational status, making it easy to monitor its activity. The auto on/off feature simplifies daily use, as the subwoofer will automatically activate when needed and power down when idle, eliminating the need for constant manual intervention. An IR receiver is integrated, suggesting the possibility of remote control operation, which would further enhance convenience, allowing adjustments from the listening position.
The downward-firing design of the driver means that the subwoofer's output is less directional, potentially making placement less critical and helping to integrate the bass more smoothly into the room's acoustics. The inclusion of a DC fan indicates active cooling for the amplifier, ensuring stable operation even during extended periods of high-power output.
While the manual primarily focuses on parts lists and schematics, certain aspects imply design considerations for maintenance. The modular construction, with separate PCB assemblies for LED indicators, SMPS, and pre-amp/power amp, suggests that individual sections can be serviced or replaced if necessary. This modularity can simplify troubleshooting and repair processes, potentially reducing downtime and repair costs.
The detailed parts list, including specific component types and locations, is invaluable for technicians performing repairs. It allows for precise identification and sourcing of replacement parts, ensuring that the subwoofer can be restored to its original performance specifications. The schematic diagrams provide a clear understanding of the circuit operation, aiding in fault diagnosis.
The presence of heat sinks for power components, along with a DC fan, indicates a design focused on thermal management. Proper cooling is essential for the longevity and reliability of electronic components, especially in a high-power amplifier. Regular cleaning of the fan and heat sinks to prevent dust buildup would be a recommended maintenance practice to ensure efficient cooling.
The use of standard connectors and wiring assemblies, as indicated in the parts list, simplifies the process of disassembling and reassembling the unit for service. The inclusion of various washers and screws also points to a design that allows for secure assembly while facilitating access for maintenance.
Overall, the KEF PSW 3500 is engineered as a robust and flexible powered subwoofer, designed to deliver powerful and controlled bass. Its internal architecture, with dedicated signal processing, a powerful amplifier, and efficient power supply, is geared towards high-performance audio reproduction, while its user-centric features aim for seamless integration and convenient operation within a home audio system.
Audio Specifications| LF Drive Unit | 300 mm |
|---|---|
| crossover frequency | 40 Hz - 140 Hz |
| frequency range | 30 Hz - 250 Hz |
Power| amplifier power | 300 Watts |
|---|---|
| maximum output (SPL) | 110 dB |
| magnetic shielding | Yes |
Weight and Dimensions| weight | 22.5 kg |
|---|---|
| dimensions | 450 x 600 x 395 mm |
