Cyrus 40 PSU

The Cyrus 40 PSU is an external power supply designed for 40 Series components. It incorporates a microprocessor that communicates with these components to optimize their electrical configuration. The unit features five independent digitally regulated power supplies, engineered to enhance hi-fi system performance.

A powerhouse of technology in a compact chassis

The 40 PSU comes in the signature black anodized aluminum chassis of the 40 Series, with identical dimensions to other components in the range (88 x 220 x 365 mm). This aesthetic uniformity allows seamless visual integration into your system. Despite its discreet appearance, the enclosure houses a high-capacity toroidal transformer and sophisticated circuitry, totaling 9.4 kg—a weight that reflects the quality of the internal components.

The rear panel reveals the complexity of the device with its proprietary multi-pin connector that routes the five distinct power rails to the host device via the supplied multi-core umbilical cable. This single connection is enough to establish bidirectional communication between the PSU and the connected device. A mini-USB port enables firmware updates, ensuring your investment remains compatible with future system developments.

The onboard microprocessor is the brain of this power supply. It analyzes the connected device’s needs in real time and dynamically adjusts output parameters to maintain optimal power delivery. This built-in intelligence fundamentally differentiates the 40 PSU from traditional passive power supplies, enabling constant adaptation to the variable demands of the audio circuit.

Five power supplies for optimal circuit separation

The technical core of the 40 PSU is built around five independent power supplies, each designed for a specific role. A high-capacity logic supply delivers stable current to digital circuits, maintaining +5V DC in standby as well as during operation. This absolute stability ensures flawless operation of processors and digital clocks.

Two fixed-voltage supplies power sensitive analog circuits. The first goes from 0V in standby to +24V DC in operation, providing perfectly regulated voltage to preamplification stages and control circuits. These supplies use specially selected low-noise regulators to keep residual noise at a practically imperceptible level.

The two variable supplies deliver the system’s knockout punch. Capable of providing an adjustable regulated voltage from +10V to +45V DC, they adapt to the specific needs of each connected device. These supplies also offer two unregulated modes (+45V or +56V DC) to deliver massive power reserves to amplifier output stages. This flexibility allows the 40 PSU to adapt perfectly to the unique electrical characteristics of each 40 Series product.

The physical and electrical separation of these five power supplies eliminates crosstalk between digital and analog sections. Each supply operates in its own isolated domain, with separate grounds and individual shielding. This isolation pushes the signal-to-noise ratio to heights rarely achieved in this price range.

Tailored sonic transformation for each device

With the 40 AMP, the external power supply takes over the entire preamplification section, allowing the internal supply to focus exclusively on the DAC section. The power amplifier rails receive a substantial injection of clean energy that significantly stiffens their behavior. The amplified signal then tracks the input with surgical precision, revealing micro-details previously masked by background noise.

When the 40 CD is connected to the PSU, its master clock is powered by an ultra-stable source, drastically reducing jitter—those tiny timing variations that blur digital accuracy. The CD drive’s motors, notorious sources of electromagnetic interference due to constant speed changes, receive a dedicated and isolated power supply. This externalization reduces overall noise inside the player’s chassis.

Separating the DAC’s analog and digital power supplies limits the transfer of high-frequency noise between these critical sections. The 40 CD’s internal power supply focuses on the converter’s digital section while the 40 PSU handles the analog stage. This division of labor translates into noticeably improved timing accuracy, tighter control of low frequencies, crisper, more controlled transients, and a more stable, deeper stereo image.

For the 40 ST, the PSU simultaneously powers the DAC’s analog side and the BluOS network module. This setup provides these critical sections with cleaner, more stable power than is available internally. The new levels of detail revealed transform the listening experience: instruments and voices gain definition and presence, creating more space around each sound source. The soundstage widens and deepens, offering a holographic presentation of the music.

Simplified installation and connection

Setting up the 40 PSU is disarmingly simple. The supplied umbilical cable connects securely between the PSU and the compatible host device. Once the connection is established, the host device automatically detects the presence of the external power supply and instantly switches to this superior power source. The host device’s display visually confirms activation of the external PSU.

No manual configuration is required: the 40 PSU’s microprocessor communicates with the connected device to identify its specific needs and automatically configures the appropriate output voltages. This onboard intelligence eliminates any risk of configuration errors and ensures that each device receives exactly the power it needs to operate optimally.

Physical placement of the PSU deserves consideration. While the umbilical cable allows some flexibility, placing the PSU a reasonable distance from other components minimizes potential electromagnetic interference. Natural convection provides sufficient cooling, with the aluminum chassis acting as a passive heatsink. The unit operates in complete silence, with no fan or mechanical noise.

Technical Specifications

Key features

• High-capacity external power supply for all Series 40 products
• Embedded microprocessor for optimized digital power management
• 5 independent power rails for analog and digital circuits
• Reduced noise, improved jitter, and enhanced sonic precision
• Increased power and stability for 40 AMP, 40 CD, and 40 ST
• Elegant Series 40 design, seamless system integration

Electrical specifications

• Low-voltage supply: +5 V DC (standby and operational)
• Fixed-voltage supply: 0 V (standby), +24 V DC (operational)
• Variable supply: 0 V (standby), +10 to +45 V DC regulated, +45 or +56 V DC unregulated
• 5 independent power supplies routed to the device for maximum optimization

Connectivity

• Multicore umbilical cable to the host product
• Mini USB: firmware updates

Construction and design

• Brushed black anodized aluminum chassis, Series 40 design
• Identical dimensions and weight to the range for perfect integration

Dimensions and weight

• Dimensions (H x W x D): 88 x 220 x 365 mm
• Weight: 9.4 kg

Sound improvements by host product

With the 40 AMP

• Delivers clean, stable power to the amplification section
• Improves input signal tracking, increasing transparency and detail
• Powers the preamp for enhanced precision
• Reduces the load on the internal DAC for greater robustness and sonic authority
• Result: more weight, better attack, precise note control, and optimized timing

With the 40 CD

• Powers the master clock to reduce jitter
• Powers the CD motors, reducing circuit noise
• Separates the DAC’s analog and digital power supplies to limit noise transfer
• Result: improved timing accuracy, sharper transients, tighter bass, and enhanced soundstage

With the 40 ST

• Powers the DAC’s analog stage and the BluOS network module
• Provides a cleaner, more stable supply for the network player
• Result: more detail, greater depth, holographic soundstage, and better-defined instruments and vocals