DAC 4.1x IZVOR
Balanced
Available finishes
Fascia - Anodised Aluminium or Black Acrylic
(custom colour fascias on request)
Current models
DAC4.1x IZVOR Balanced
DAC4.1x IZVOR Balanced Signature
IZVOR DAC TECHNOLOGY
Digital playback has never sounded so full bodied,
tonally rich, naturally flowing, and ‘real’.
In 2014, our design engineer Darko Greguras began exploring the possibility of dispensing with the conventional Digital To Analogue converter chip. Instead, his aim was to create a discrete R2R Ladder DAC, using only the finest quality analog circuit components.
Following twelve years of meticulous research and development, we give you the IZVOR DAC, a groundbreaking, breathtaking revelation.
The IZVOR distinguishes itself as the first-ever DAC to use large, hand-soldered resistors rather than the usual surface-mount components typically found in ladder DACs.
Darko was able to fine-tune the IZVOR’s voicing by testing and selecting components from our vast selection of custom options, even going so far as designing an entirely new resistor for the project.
Below is a description of the development process from Darko: -
“The word ‘Izvor’ can have many meanings but one stood out and best reflected the intention behind this project. For me, ‘Izvor’ represented going back to the fundamentals of digital-to-analogue conversion: exploring the engineering essence while staying in harmony with the materials and metallurgy.
This project has been driven for years by a passion to return to the basics, using selected, well-known and refined components to create a harmonious, discrete multibit digital-to-analogue converter.
Why? Because when you apply a carefully balanced group of parts, every step forward yields a fuller, smoother, and richer performance. In much the same way musical instruments are built, the key lies in harmonious and complementary properties.
Sound wise, the goal was to achieve greater contrast and grip, improved authenticity and timing, but at the same time a very composed and lush presentation.
This project did not come without its challenges. The resistors I wanted to use have a tolerance of 1%, which (if used in a conventional way, as other manufacturers do) is insufficient even for 14-bit performance in a discrete segmented DAC. So we had to think creatively and look for innovative solutions.
The technical design target was to stay within the AD1865 DAC chip specification, but to improve on it both objectively and subjectively, especially at very low signal levels. This Discrete DAC was modelled and designed around a segmented structure; 3 bits in the MSB and 16bits in the R2R sections. Particular attention was given to performance below −60 dBFS, where ambience, decays, and subtle details live. Izvor’s settling time was never in question due to a specific choice of the analogue switches and very careful decoupling.
To achieve this, we developed fast I²S real-time compensation and used measurement equipment with reliable 1-ppm accuracy. Corrected values were stored individually on each DAC board, each being effectively unique. This kept my friend and colleague Andrejs very busy!
There is no oversampling and no digital or analogue filtering, only a circular I²S buffer.
We tested everything at DC-level precision using an 8.5-digit laboratory instrument. The final result exceeds the AD1865’s measured dynamic range by more than 4 dB and, subjectively, the way the DAC loads the room feels far closer to an analogue source.
None of this would have been possible without a proper shunt power supply to support such demanding requirements and it was designed, specifically for the DAC, by Andy Grove. It is a solid-state interpretation of our patented Galahad feed-forward power supply, making it possibly to reach −130 dB noise floor.
Was the effort worth it? Absolutely!”
DETAILS
The Audio Note DAC4.1x IZVOR Balanced is one of the most unique digital product available today. It uses our patented and innovative digital circuit, combined with some of the finest components, materials and power supplies possible.
Extensive research into the fundamental properties of the data stream itself have shown beyond doubt that, regardless of the theoretical advantages of the signal manipulation employed in our competitors products, such as higher oversampling, noise shaping, re-clocking or jitter reduction, these corrective measures greatly interfere with the critical time domain requirements of the signal.
Music is a time continuum from start to end which when broken is irreparably damaged, and no amount of clever manipulation can restore it to its original time / frequency / amplitude duration or relationship, regardless of what the theorists may tell you.
As a result, we have developed a way of excluding or bypassing all these corrective measures, to allow the conversion from digital to analogue to be done without any manipulation whatsoever. All we do is reformat the data stream to allow the converter chip to be able to interpolate the incoming information correctly.
In other words, the Audio Note (UK) DAC4.1x IZVOR Balanced has no oversampling, no jitter reduction, no noise shaping and no re-clocking. Having removed all of the digital filtering that is required for over sampling, all filtering is done in the analogue domain where it is easier to retain good, wide band phase-frequency and dynamically coherent behaviour.
DESIGN AND COMPONENTS
Once the audio signal exits the IZVOR discrete R2R Ladder DAC module, it is fed into a pair of our in-house designed and manufactired copper / copper filter-interface transformers. The air gaps in the two filter coils are matched across the full frequency range to within 0.1dB of each other, using a specially designed program to supplement an Audio Precision System 2 test rig.
The two versions of the DAC4.1x IZVOR Balanced feature an upgraded version of the M6 preamplifier line stage, using a 5814a (ECC82/12AU7a) and a 5687, both of which are dual triode valves. These are coupled to the output transformers, which are wound with Audio Note (UK) copper wire for the primary and secondary With a 33:1 step-down ratio. These output transformers not only have exceptionally wide frequency response, but also just about the absolutely best dynamic transfer function possible. The analogue output provides both single ended / RCA and balanced / XLR connections.
The DAC4.1x IZVOR Balanced features a dual-channel power supply with double-choke filtering and valve rectification. This technique not only provides excellent isolation between the digital circuitry and power supply, but also provides well-isolated short and clean analogue signal paths.
For the DAC4.1x IZVOR Balanced Signature, we chose to use a version of our patented Galahad feed-forward power supply, as used on our M6 preamplifier.
This PSU features full valve rectification, regulation and voltage stabilisation. This technique not only provides excellent isolation between the digital circuitry and power supply, but also provides well-isolated short and clean analogue signal paths.
The digital power supply for both modles is an exceptionally low noise, shunt-type, designed specifically for the DAC, by Andy Grove. It is a solid-state interpretation of our Galahad feed-forward power supply, making it possibly to reach a −130 dB noise floor.
Some of the superior quality components used in the DAC4.1x IZVOR Balanced include: -
IZVOR Module; 1w non-magnetic Nichrome resistors
Audio Note (UK) 0.5 Watt and 1 Watt non-magnetic Tantalum resistors
Audio Note (UK) copper foil signal capacitors used in critical areas
Audio Note (UK) Standard and Kaisei NP electrolytic capacitors used in critical areas
In-house designed and manufactured copper / copper interface transformers
In-house designed and manufactured copper / copper SHiB core output transformers
In-house designed and manufactured BA I-E mains transformer
In-house designed and manufactured I-E PSU choke
Some of the superior quality components used in the DAC4.1x IZVOR Balanced Signature include: -
IZVOR Module; 1w non-magnetic Nichrome resistors, silver lead-outs
Audio Note (UK) 1 Watt non-magnetic Tantalum resistors
Audio Note (UK) copper foil signal capacitors used in critical areas
Audio Note (UK) Standard and Kaisei NP electrolytic capacitors used in critical areas
In-house designed and manufactured copper / copper interface transformers
In-house designed and manufactured copper / copper UHiB core output transformers
In-house designed and manufactured I-E mains transformer
In-house designed and manufactured I-E PSU choke
Technical Specifications
INPUT
OUTPUT IMPEDANCE
REFERENCE OUTPUT
CHANNEL BALANCE
VALVE COMPLEMENT
UNIT WEIGHT
UNIT DIMENSIONS
DIGITAL SYSTEM
NOTE
RCA 75 Ohms SPDif
XLR 110 Ohms AES/EBU
600 Ohms, Balanced or Single Ended
3.2V RMS
Less than 0.2dB
1 x 5814a
1 x 5687
1 x 6X5
1 x ECL82
1 x 5651 (Signature version only)
22 kg
145mm (h) x 450mm (w) x 425mm (d)
18-Bit IZVOR DAC module
44.1 / 48 / 96KHz input capability.
Due to Audio Note (UK)'s ongoing research and development program, specifications are subject to change without notice.
