The Monitor Audio IWA-250 is the dedicated active amplifier module at the heart of Monitor Audio's IW-SUB-S and IW-SUB-T in-wall subwoofer systems. Housed in a slim, heavy-duty 1U rack-mount steel chassis, it delivers 250 W into 4 ohms to power one or two IWS-10 in-wall subwoofer drivers — providing the deep bass foundation for a custom installation cinema or multi-room audio system without a freestanding subwoofer cabinet.
Class D Amplification and Switch-Mode Power Supply
The IWA-250 uses a Class D power stage driven by a switch-mode power supply (SMPSU). This topology delivers high efficiency with minimal heat dissipation — the unit is described by Monitor Audio as cool running — making it well suited to rack installation in confined equipment bays where thermal management is critical. Protection circuitry guards against DC short circuit, over-current, and thermal overload conditions.
DSP Control and EQ Presets
An integrated DSP handles all filtering and control functions in software, providing precise and reliable operation. Three front-panel EQ presets — Music, Movie, and Impact — allow the system to be optimised for different programme material without additional outboard processing. A phase switch provides 0° and 180° options for matching the subwoofer's output to the room's acoustic conditions. An enclosure switch on the front panel calibrates the IWA-250's drive characteristics for use with the IWS-10 either with or without the IWB-10 pre-construction back box — accommodating both sealed and open-back installation configurations.
Inputs and Trigger Control
The IWA-250 offers three signal input paths: a stereo RCA pair, a single-ended RCA LFE input, and a balanced XLR LFE input — covering the full range of AV receiver and processor output configurations. Input impedance exceeds 20kΩ across all inputs. A 3.5mm 12V trigger input allows the amplifier to be switched on and off directly by an AV receiver or system controller. Alternatively, the IWA-250 includes auto-sensing activation: it powers up when a line-level signal above 3.5mV is detected and enters standby automatically after approximately 15 minutes without an input signal. Standby power consumption is less than 0.5 W, meeting ErP (Energy-related Products) certification requirements.
Installation and Compatibility
The 1U rack-mount form factor allows the IWA-250 to sit neatly in a standard equipment rack alongside source components and control systems. Speaker outputs are provided via two sets of push-type binding terminals, supporting single or dual IWS-10 driver configurations. The IW-SUB-S system uses a single IWS-10; the IW-SUB-T system uses two drivers for larger installations.
| Power Output | 250 W (into 4 ohms, <1% THD+N) |
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| Amplifier Class | Class D |
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| Power Supply | Switch-mode (SMPSU) |
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| Frequency Range | 25 Hz – 120 Hz |
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| Crossover Frequency | Variable, 40–120 Hz @ 24 dB/Oct |
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| Inputs | Stereo RCA, LFE (RCA), Balanced LFE (XLR), 12V Trigger (3.5mm jack) |
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| Input Impedance | >20 kΩ |
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| Speaker Outputs | 2 × push-type terminals |
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| EQ Modes | Music, Movie, Impact |
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| Phase Control | 0° / 180° |
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| Auto-Sensing Threshold | 3.5 mV (line level) |
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| Standby Power | <0.5 W (ErP certified) |
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| Idle Power | <10 W |
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| Max Power Consumption | 200 W |
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| Dimensions (H×W×D) | 43.7 × 432 × 263 mm (1U rack mount) |
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| Weight | 4 kg |
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