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Delta 25 4FS

Powered Twin 15" Flying Subwoofer with a 4 Ch, 6KW System Powerplant
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Product at a Glance

The Delta 25 4FS is a twin 15” High Output Subwoofer that provides a powerful and extended low frequency response with ample headroom. It’s optimal enclosure design allows for very low port compression and delivers a tight and accurate bass response which is ideal for touring & high performance installation applications.

The Delta 25 4FS houses an ultra long excursion 15” ultra low distortion driver. A 4” voice coil ensures a linear excursion of 20mm at a steady magnetic force. The Delta 25 4FS can be integrated into flown arrays or ground stacked systems with the Alpha 428LA Line Arrays. They can also be coupled with upto 3 x Alpha 425 FS for a Subwoofer Stack.

The amplification, networking & signal processing are housed within the Delta 4S system power plant, which includes 4 channels of Class D amplifications - 1 channel for the subwoofer itself and 3 channels to power additional Line Array or Subwoofer Systems.

The Delta 25 4FS was primarily designed as a low frequency extensions woofer with the LFE-GS preset. There is also a LMB-F preset for use as a flying subwoofer with the Alpha 428LA. With the options of a cardioid or omni-directional presets, the Delta 25 4FS is suited for touring and install applications where high precision, optimal dispersion control and deep bass is needed.


Painstakingly Perfect Production

Over the years, craftsmanship has been closely linked with small scale individualistic production. Back in 1972, we started the same way. As we grew in scale & size, it was difficult to build each speaker individually, but quality control was of utmost importance as so switching to a general assembly line was simply not an option. So we wrote up a code, one quite like enigma, to ensure quality control. We selected the right partners, got the right tools, and in cases where those weren't available, we invented them. We grew slower than most as our aim was to last longer than most. 

Tech Specs



Frequency Response (-3 dB)

31Hz - 150Hz

Frequency Range (-10 dB)

26Hz - 150Hz

Amplifier Power for Subwoofer

1500W Continuous, 3000W Peak

System Amplifier Power

1500W @ 8 Ohms (3 Channels)

Maximum SPL

138 dB Peak (LFE-GS Preset)


Coverage Pattern

Omnidirectional, Cardioid Presets Available.


Preset Selection Button, System Gain Potentiometer


Marine Birchwood Cabinet, Premium Grade


Powder-coated durable grill with acoustically transparent foam

LF Driver

15” Ultra Low Distortion Woofer, 4” Voice Coil, 800W AES.

Input Connectors

2 x Neutrik XLR, 2 x Neutrik PowerCons & 2 x Cat-6 Control Inputs


British Acoustics' Signature Brown Finish

Mounting System

Integrated 4 point Rigging System with Lock-n-StockTM Mechanism

AC Power Input

Universal power supply 100 - 240 VAC, 50 - 60 Hz









57 Kgs

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We have a growing network of channel partners

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