Detail

Audio Note (UK) DAC4.1x digital-to-analog converter is designed specifically for sonic performance rather than technical specifications, and meets all Audio Note (UK) Level 4 standards:—

Pure Class A operation

Zero negative feedback

Single-ended circuit topology

Vacuum tube rectification

Material and Component Quality

Extensive research into the fundamental properties of the data stream itself demonstrates—beyond doubt—that regardless of the theoretical advantages of signal processing techniques employed in competitors’ products (such as higher sampling rates, noise shaping, re-clocking, or jitter reduction), these corrective measures significantly interfere with the signal’s critical time-domain requirements.

Music is a temporal continuum extending from beginning to end; once it is disrupted by intermittent breaks, it cannot be restored—and no matter what theorists may tell you, no amount of clever manipulation can return the music to its original temporal, frequency, or amplitude relationships.

As a result, we developed a method to eliminate or bypass all these corrective measures, thereby enabling the digital-to-analog conversion to be performed without any additional processing. All that was required was to reformat the data stream so that the converter chip could correctly interpolate the incoming information.

In other words, Audio Note (UK) DAC4.1x employs no oversampling, jitter reduction, noise shaping, or re-clocking. By eliminating the digital filtering required for oversampling, all filtering is performed in the analog domain—where it is easier to maintain excellent wideband phase-frequency and dynamic coherence characteristics. It utilizes the top-grade Analog Devices AD1865 18-bit stereo converter chip, simply because we found it to offer the best sound quality available (yes, even better than the 20-bit version!).

Filter interface coils/transformers utilize top-quality 80% nickel Super Mu-Metal cores. A specially designed procedure—complementing the Audio Precision System 2 test bench—is used to match the air gaps of the two filter coils in each channel across the entire frequency range, ensuring a deviation of no more than 0.1 dB between them.

DAC4.1x Balanced features an upgraded output stage derived from M6 ​​Line preamplifier, utilizing 5814a and 6463 dual-triode tubes. It is coupled via an output transformer wound with Audio Note (UK) copper wire on a high-quality B-C core. With a step-down ratio of 33:1, this output transformer delivers not only an exceptionally wide frequency response but also a near-optimal dynamic transfer function. The analog outputs employ premium-quality RCA and XLR connectors, supporting both unbalanced and balanced operation.

DAC4.1x Balanced Signature utilizes a pair of 5687 dual-triode tubes, featuring an output stage derived from M6 ​​line preamplifier. It is coupled to an output transformer wound with Audio Note (UK) copper wire on a High-B C-core. With a step-down ratio of 33:1, this output transformer delivers not only an exceptionally wide frequency response but also a near-optimal dynamic transfer function. The analog outputs employ top-quality RCA and XLR connectors, supporting both unbalanced and balanced operation.

To power this impressive assembly, we combine a dual-rail power supply with dual-stage filtering and tube rectification. This approach not only ensures excellent isolation between the digital circuitry and the power supply but also facilitates a short, clean, and well-isolated analog signal path. The digital power supply is an ultra-low-noise, shunt-regulated design.

The quality of the internal components in this chassis is unlike anything seen in consumer or professional equipment. Audio Note (UK) capacitors and tantalum film resistors are used extensively throughout the circuitry. The analog stage filter inductors and internal wiring are all constructed using Audio Note (UK) wire.

Technical specifications

RCA 75-ohm S/PDIF Input

XLR 110-ohm AES/EBU

Output impedance 600 ohms, balanced or single-ended.

Reference output: 1.5V RMS (balanced) / 3.2V RMS (balanced signal)

Channel balance less than 0.2 dB

Vacuum tube 1 x 5814A

1 x 5687WB (balanced) / 1 x 6463 (balanced signal)

1 x ECL82

1 x 6X5

Unit weight: 22 kg

Unit dimensions: 145mm (H) x 450mm (W) x 425mm (D)

Digital Systems: 18-bit Analog Device AD1865N

44.1 / 48 / 96 kHz input capability

Notice

Due to Audio Note (UK)’s ongoing research and development program, specifications are subject to change without notice.Due to Audio Note (UK)’s ongoing research and development program, specifications are subject to change without notice.