Bowers & Wilkins CDA-4D

The Bowers & Wilkins CDA-4D is a four-channel power amplifier designed for integrated audio installations. It delivers 125 watts per channel via Class D amplification and includes digital signal processing (DSP). Its 1U form factor and 19-inch rack-standard chassis make it easy to integrate into custom audio systems. The unit can power in-wall speakers from the Custom Installation range and manage two distinct listening zones.

Compact design and efficient Class D amplification

The CDA-4D features a 1U rack form factor (height of 42.5 mm without feet) with a standard width of 437 mm, making it particularly suitable for technical racks where every centimeter counts. With a depth of 310 mm and a net weight of 4.1 kg, it fits easily into tight spaces without requiring special reinforcement.

The amplifier incorporates Class D technology based on ICEpower modules, originally developed by Bang & Olufsen. These modules use switching transistors that operate only in the “on” or “off” position, thereby minimizing energy losses compared to traditional Class AB architectures. This approach achieves energy efficiency above 90%, significantly reducing thermal dissipation. In standby, the CDA-4D consumes less than 0.5 watt, and its universal 100–240 V power supply automatically adapts to different international electrical standards.

Cooling is provided by an integrated ventilation system that keeps components at a stable temperature even during prolonged high-power use. This effective thermal management eliminates the risk of thermal shutdown, a common issue with less well-designed amplifiers.

Power and amplification flexibility

The CDA-4D delivers 125 watts per channel into a 4-ohm load, or 60 watts into 8 ohms. Total available power exceeds 125 watts in continuous use, with peaks reaching 500 watts in transient mode. The amplifier can operate with loads down to 3 ohms per channel (or 6 ohms in bridged mode), offering broad compatibility with different speakers.

Bridged configuration allows two channels to be combined to obtain a 250-watt mono output into 8 ohms. This flexibility is particularly useful for powering a subwoofer or a power-hungry center speaker. A 2.1 setup is also possible: two 125-watt channels for the main speakers and one bridged 250-watt channel for the subwoofer.

Voltage gain is adjustable from 15 dB to 39 dB, allowing the amplifier to be matched to different sources and input levels. The 10 kΩ input impedance ensures compatibility with most preamplifiers and audio processors. The maximum accepted input voltage is 4 Vrms.

Built-in DSP for precise acoustic optimization

The onboard digital signal processing is one of the CDA-4D’s major strengths. This feature allows precise tuning of amplification to the specific characteristics of Bowers & Wilkins speakers from the Custom Installation range. The DSP offers dedicated presets for the brand’s speaker and subwoofer models, including the ISW-3, ISW-4, and ISW-6 subwoofers.

Dynamic EQ for subwoofers automatically adjusts frequency response according to output level, optimizing low-frequency extension while protecting the drivers. Built-in limiters prevent damage from accidental overload. The DSP also enables fine adjustments of phase, delay, and tone control for each channel, facilitating time alignment across the different speakers in a system.

Configuration is done via a web interface accessible over Ethernet. This approach simplifies complex adjustments and allows centralized parameter management. The CDA-4D can auto-sense a signal and switch to active mode, or be controlled via a 12 V trigger input. After 15 minutes without a signal, the amplifier automatically goes into standby to save energy.

Connectivity and multi-zone management

The CDA-4D’s rear panel offers two stereo analog inputs on RCA phono connectors and two digital inputs also on RCA phono. An Ethernet port provides network connectivity for configuration and control. Outputs use 4-way Phoenix Combicon connectors with a 5.08 mm pitch, making speaker wiring easy and allowing quick connects and disconnects.

The zone management system can power two independent zones with different sources. The CDA-4D provides source prioritization functionality: Source 1 can be defined as the main source, Source 2 can take priority and mute Source 1, or both sources can be mixed when Source 2 receives a signal. This flexibility is useful for installations where multiple users may want to control audio simultaneously.

The 12 V trigger system includes a 3.5 mm input jack and a 3.5 mm output jack to pass the signal to other equipment (up to 100 mA). This trigger chain simplifies automation of multi-component systems.

Technical specifications

Main features

• Compact and powerful 4-channel amplifier with 125 W
• Built-in digital signal processor for dynamic equalization
• Fully compatible with the Bowers & Wilkins Custom Installation range
• Full-width 1U rack design, ideal for multi-room installations
• Exemplary reliability and energy efficiency
• Low distortion under 1% and wide dynamic range

Audio performance

• Output power: 4 x 125 W
• Load impedance: greater than 3 Ω per channel, greater than 6 Ω in bridged mode
• DC offset voltage: less than 50 mV
• Frequency response at -3 dB: below 10 Hz up to above 30 kHz, regardless of load impedance
• Response accuracy between 20 Hz and 20 kHz: ± 1 dB
• Dynamic range: greater than 85 dB A-weighted
• Total harmonic distortion + noise at 1 kHz, 500 W, 4 Ω: less than 1%
• Voltage gain: adjustable from 15 dB to 39 dB
• Input impedance: 10 kΩ
• Maximum input voltage: 4 Vrms

Connectivity

• Audio inputs
  • 2 analog RCA phono connectors
  • 2 digital RCA phono connectors
• Network input
  • 1 Ethernet port
• Audio outputs
  • 2 Phoenix Combicon 4-way connectors, 5.08 mm pitch
• 12 V trigger
  • 1 x 3.5 mm jack input
  • 1 x 3.5 mm jack output with maximum pass-through current of 100 mA

Power and thermal management

• Standby power consumption: less than 0.5 W, network wake enabled or disabled
• Mains power: 100 – 240 V ~ 50 / 60 Hz
• Heat dissipation
  • Standby: 0.5 W (1.7 BTU/h)
  • Idle: 38 W (130 BTU/h)
  • Full load: 147 W (500 BTU/h)

Dimensions and design

• Height: 42.5 mm, 55.5 mm with feet
• Width: 437 mm
• Depth: 310 mm
• Net weight: 4.1 kg
• Form factor: 1U for 19-inch rack mounting
• Finish: satin black