The Dayton Audio SA240 Subwoofer Plate Amplifier is a 240-watt amplifier designed for high-quality sound reproduction in both home stereo and home theater systems. It is engineered to provide years of reliable performance with a comprehensive set of features for optimal subwoofer integration and protection.
Function Description:
The SA240 serves as a dedicated amplifier for passive subwoofers, providing the necessary power and signal processing to integrate a subwoofer into an existing audio system. It accepts both line-level and speaker-level audio inputs, offering flexibility for connection to various sources such as pre-amps, home theater receivers, or full-range amplifiers. The amplifier features a variable low-pass crossover, phase control, and an auto-on/off circuit, allowing for precise tuning and seamless operation with main speakers. The SA240-B model includes an additional bass boost feature (6dB @ 30Hz) for enhanced low-frequency impact.
Important Technical Specifications:
- Rated Power Output:
- 150 watts RMS into 8 ohms @ 0.1% THD
- 240 watts RMS into 4 ohms @ < 1.0% THD
- Based on one-third power duty cycle
- Signal to Noise Ratio: 90 dB A-weighted
- Efficiency: 66%
- Input Impedance: 12K ohms
- Bass Boost:
- SA240: None
- SA240-B: 6dB @ 30Hz
- Low Pass Adjustment: 40 Hz - 180 Hz (4th order, 24 dB/octave slope)
- Phase Adjustment: 0° (NOR) or 180° (REV)
- Dimensions: 9-13/16" W x 9-13/16" H x 5" D
- Enclosure Cutout: 8-1/2" x 8-1/2"
- Power Requirements: 115/230 VAC, 50 Hz/60 Hz, 400W
- Weight: 12 lbs.
Usage Features:
- Input/Output Connections:
- Low-Level Inputs (Left/Right): RCA jacks for standard line-level inputs from a pre-amp or home theater receiver. These inputs combine stereo signals into mono. For mono sources or LFE outputs, a "Y" cord is suggested.
- Low-Level Outputs (Left/Right): RCA jacks that pass the low-level input signal through without alteration, allowing for daisy-chaining to other amplifiers.
- High-Level Inputs: Binding post type jacks for speaker-level inputs from a full-range amplifier. A mono signal is derived from stereo inputs to feed the subwoofer amplifier crossover.
- High-Level Outputs: Binding post type jacks to pass signal from the full-range amp to the main L/R speakers. This output is active only if high-level inputs are used and includes an internal 6 dB/octave 125 Hz high pass filter.
- Power Input: IEC grounded type power jack with an integrated fuse holder. The unit is factory-set for 115V operation with a 5A, 250V fuse. For 230V operation, a 2.5A, 250V fuse and a separate power cord are required (not included).
- Output Lead for Subwoofer Driver: A rear-mounted lead (approx. 20" long) with color-coded insulated quick disconnects (.250" red for positive, .205" black for negative) connects the amplifier to the subwoofer driver.
- Controls/Indicators:
- Gain Control: Matches the amplifier's input sensitivity to the source output, acting as the "volume control" for the subwoofer system.
- Frequency Control: Establishes the highest frequency the subwoofer will reproduce (40-180 Hz, 24 dB/octave slope). For LFE outputs from home theater receivers, it should be set to maximum (180Hz) to bypass the internal low-pass filter.
- Power LED: Illuminates green when the amp is "On" or in "Auto" mode with an input signal. Turns off in "stand by" mode without an input signal. Turns red if the protection circuit detects a short circuit or thermal overload.
- Power Switch: Three modes: "On" (always on), "Off" (always off), and "Auto" (enters "stand by" mode and activates when a signal of ~10mV or greater is detected, returning to standby after 10-15 minutes without a signal).
- Phase Switch (NOR/REV): A two-position switch (0° or 180°) to compensate for acoustical and electrical differences between the subwoofer and main speakers, aiding in system integration.
- Voltage Selector Switch: Allows selection between 115V and 230V operation. The unit is factory-set for 115V. Users must change the fuse to 2.5A, 250V for 230V operation.
- Protection Circuits: Comprehensive internal protection against shorted speaker loads, thermal faults, and overload conditions ensures extreme reliability.
- Soft-Clip Circuitry: Provides clean output even with demanding program material, improving headroom and protecting woofers.
- Hum Reduction: Designed to minimize hum, but in rare cases, hum may occur due to grounding issues or cable TV systems. Solutions include ensuring all audio components are on the same electrical circuit, disconnecting coaxial feeds, or using a coaxial line isolator/transformer.
Maintenance Features:
- User Serviceability: The manual explicitly states: "TO REDUCE THE RISK OF ELECTRIC SHOCK, DO NOT REMOVE COVER (OR BACK). NO USER-SERVICEABLE PARTS INSIDE. REFER SERVICING TO QUALIFIED SERVICE PERSONNEL."
- Fuse Replacement: The IEC power input houses an integrated fuse holder. The unit is supplied with a 5A, 250V fuse for 115V operation. For 230V operation, a 2.5A, 250V fuse is required.
- Cleaning: Clean only with a dry cloth.
- Ventilation: The unit should be operated in a well-ventilated area with a minimum clearance of 2 inches from ventilation openings. Avoid installing near heat sources.
- Power Cord Protection: Protect the power cord from being walked on or pinched, especially at the plugs, convenience receptacles, and where it exits the unit.
- Safety Warnings: Includes standard warnings regarding electric shock hazard, not opening the unit, and not exposing it to rain or moisture. It also states the unit is "NOT SUITABLE FOR IN-WALL MOUNTING."
- Warranty: Dayton Audio products are warranted for one year against manufacturer defects in materials or workmanship. The warranty does not cover incidental or consequential damage, or damage from defective or improper use (e.g., burnt voice coils, overheating). Non-warranty service is available by contacting the company.
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