Description

Aries Cerat Kassandra Signature Limited Edition DAC

The Kassandra Signature Limited Edition represents the highest level of digital conversion within the Kassandra series from Aries Cerat. Designed as the ultimate statement in digital replay, it pushes the boundaries of what is possible in digital-to-analogue performance.

From the earliest stages of Aries Cerat’s development, it was clear that a true state-of-the-art digital source was essential. Designing world-class amplifiers, loudspeakers, and preamplifiers requires a source component capable of revealing every nuance of the musical signal. The Kassandra platform was created to fulfill that role, combining the tonal richness and musical flow of the finest analogue sources with the resolution, speed, and dynamic range that only advanced digital conversion can provide.

The Kassandra Signature Limited Edition takes this philosophy even further. With a dual-chassis architecture, a massively upgraded power supply system, and an expanded converter array, it represents a no-compromise approach to digital audio design.

Design Philosophy

The Kassandra Signature Limited Edition was developed as the ultimate evolution of the Kassandra converter platform. Building upon the already exceptional Kassandra Reference design, the goal was to push performance significantly further by rethinking the architecture and incorporating technologies from other flagship Aries Cerat components.

A two-chassis configuration was adopted, similar to the company’s Limited Edition amplifier designs. Separating the power supply from the main converter chassis provides additional space and electrical isolation, allowing the engineers to implement far more sophisticated power supply technologies. Many of these techniques were derived from the flagship Aries Cerat Impera Limited Edition Preamplifier, particularly in the design and regulation of the power supply.

The result is a digital source designed without limitations, representing the highest expression of the Kassandra concept.

R2R Ladder DAC Architecture

At the core of the Kassandra Signature Limited Edition is a pure ladder DAC architecture. This design converts digital information using a precision resistor network controlled directly by the incoming data stream. Because the signal is converted without additional processing stages, the result is an extremely direct and natural form of digital-to-analogue conversion.

Unlike many modern DAC designs, the Kassandra avoids delta-sigma conversion and digital filtering, which can introduce unwanted artifacts that affect tonal realism and musical flow.

Instead, Aries Cerat selected the classic Analog Devices AD1865N-K converter chip, widely regarded as one of the finest sounding R2R devices ever produced. The chip features simple data handling logic and does not perform internal signal processing, allowing engineers to fully control how the conversion process is implemented.

To achieve unprecedented performance, the Kassandra Signature Limited Edition uses twenty-four R2R converters per channel, for a total of forty-eight converters operating in parallel.

Running converters in parallel offers several important benefits. It improves linearity, reduces noise and distortion, increases dynamic range, and enhances channel separation. By averaging the resistor tolerances across multiple networks, this architecture achieves extremely precise conversion accuracy while delivering a more natural and dynamic sonic presentation.

Jitter Control and Super Clock Technology

Precise timing is critical in any digital conversion system. Even extremely small timing errors can degrade clarity and affect musical realism.

The Kassandra Signature Limited Edition uses a number of advanced techniques to minimize jitter throughout the digital signal path. Carefully designed driver circuits and optimized digital line terminations prevent signal reflections and overshoot that can introduce timing instability.

The digital circuits are also isolated from power supply noise through an extensive filtering network consisting of thirty-five LC filters using RF chokes and high-speed capacitors. These filters effectively eliminate jitter originating from power supply fluctuations.

At the heart of the timing system is Aries Cerat’s proprietary Super Clock technology. This precision clock directly controls the refresh signal of the R2R converter network, ensuring that the digital data is converted with exceptional accuracy.

The Super Clock also reclocks the asynchronous USB controller and the S/PDIF receiver, synchronizing incoming signals before they reach the conversion stage. With this internal clock architecture, there is no need for an external word clock input, and jitter performance is reduced to femtosecond levels.

Transformer I/V Conversion

The R2R converter chips operate in current output mode, meaning the signal must be converted into voltage before it can enter the analogue stage.

Rather than relying on op-amps or simple resistor networks, Aries Cerat employs a custom transformer-based current-to-voltage conversion stage. This specially designed transformer converts the differential current output into a single-ended voltage signal while preserving the integrity of the musical signal.

Transformer I/V conversion offers superior transparency and dynamic capability compared with conventional conversion methods.

Tube Output Stage

After I/V conversion, the signal is amplified by a single-ended tube output stage derived from Aries Cerat’s amplifier and preamplifier designs.

The stage uses the highly regarded E280F super tube, connected in triode configuration for optimal linearity and low noise. This tube is known for its excellent transconductance and stable operating characteristics.

The triode is coupled to a large-core step-down output transformer and powered by an oversized choke-regulated power supply. This configuration allows the circuit to respond effortlessly to wide dynamic swings in the music signal while maintaining extremely low noise levels.

The step-down transformer also lowers output impedance to approximately 40 ohms and allows a maximum output swing of 30 V peak-to-peak.

Power Supply Architecture

One of the most significant upgrades in the Kassandra Signature Limited Edition is the massive power supply system.

Key elements include five large toroidal transformers and more than three Farads of total system capacitance. The system also incorporates extensive local decoupling through seventy-six tuned LC filters.

A pseudo-battery power supply architecture isolates the analogue circuitry from the power grid, significantly reducing noise and improving stability. Xenon gas rectifiers are used for the tube power supplies, further enhancing regulation and sonic purity.

This extremely robust power supply ensures stable operating conditions for every stage of the converter system.

Technical Specifications

Digital Section

• Converter architecture:
  24 R2R converters per channel using Analog Devices AD1865N-K chips (48 total)
• Current-to-voltage conversion:
  Transformer I/V conversion with custom wideband transformers
• Clock system:
  Internal Super Clock with triple regulated supply
• Voltage regulation:
  Eight discrete ultra-low-noise regulators for the converter banks

Power Supply Section

• Five toroidal transformers
• Over 3 Farads total system capacitance
• 76 tuned LC filters for extensive decoupling
• Pseudo-battery power supply system
• Xenon gas rectifiers for tube power supplies

Input & Output Section

• Gain stage:
  Transformer loaded tube output stage using E280F tube
  5:1 / 10:1 step-down transformer with double choke filtered supply
• Output range:
  RCA: 30 Vpp output at 0 dB (10 Vrms)
  5 Vrms output at −6 dB setting
• User selectable output:
  10 V @ 50 ohms
  5 V @ 12 ohms
• Outputs:
  2 × RCA
  2 × balanced XLR outputs
  True balanced output architecture
• Floating RCA output switchable for ground loop resolution
• Output impedance:
  50 ohms (balanced and single-ended)
  12 ohms at −6 dB setting

Digital Inputs

USB input supporting up to 24-bit / 384 kHz

Additional inputs:
AES/EBU, S/PDIF, BNC (others available on request)

Jitter attenuation down to femtosecond level

Physical Specifications

Dimensions:
540 mm W × 530 mm D × 165 mm H

Weight:
120 kg total

Source: https://aries-cerat.com/kassandra-signature-limited-edition-product-page/