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RT-AUDIO R2R Multibit “Orpheus” Battery DAC [Review].

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RT-AUDIO R2R Multibit “Orpheus” Battery DAC [Review] English Edition.

by D. Dravopoulos & Hiendnews Team

RT-Audio Design from Bulgaria has developed a new conceptual two-chassis R2R DAC, built around the legendary AD 1865 chip. Like all of their products, this Digital To Analog converter follows a core philosophy: simplicity leads to perfection. Its electronic architecture features a short signal path with no capacitors in the signal path and output transformers in this ‘Orpheus’ model analog output. The DAC operates in NOS (Non-Oversampling) mode without a digital filter, resulting in a sound that is more natural and analog-like (as the company suggests). In NOS mode, phase and time distortions are minimized. After extensive experimentation and research, RT-Audio eliminated unnecessary digital inputs and switches, as they can degrade sound quality. The new battery powered Multibit Orpheus R2R DAC is designed to use only a USB input, equipped with the highest-quality XMOS converter from JL Sounds for superior audio performance. It supports playback of files with 32-bit/384kHz resolution, delivering exceptional quality by removing extraneous bits through software rather than relying on standard hardware delay. They also designed a custom PCB for this DAC, ensuring short signal paths for both digital and analog stages. All electronic components used are of the highest quality, as they state. For the analog low-pass filter (LPF), RT-Audio use output transformers with a 1:1 ratio, which provide low distortion, noise, and phase shift. Additionally, all signal paths are wired with pure silver internal cabling for enhanced sound clarity. That’s how they shake up our home audio world, again!

About four years ago, we discovered that the Orpheus-series digital-to-analog converters from Sofia’s RT-Audio Design paired seamlessly with our systems, leading us to believe that for many discerning audiophiles, this could become a lifelong favorite—all at a price point that doesn’t never-ever exceed 3,000 euros ! The quest for value-for-money superiority has yielded numerous digital champions at unexpectedly reasonable prices. Recently, with the launch of their new Orpheus battery-powered R2R USB DAC, they’ve once again impressed us with exceptional sound quality at around € 2,600 price tag. Although we genuinely regret the significant delay between receiving the unit and publishing this review—over six months… We apologize for the delay, but we believe the wait was ultimately worth it!

As stated also on their official website: “The power supply is crucial for the proper functioning of a digital device and any disruption in its operation can negatively impact sound quality. For this reason, this model utilize a battery power supply with a dedicated low-noise linear charger. The rectifier features SiC Schottky diodes. The DAC section is powered by three low-noise LDO regulators from LT and Texas Instruments. Additionally, the USB converter PCB employs a low-noise LDO with less than 20μV, ensuring galvanic isolation.” – RT designers team.

So… What is an R2R DAC ?

Curious to dive deep into the technical aspects of R2R design philosophy? Check out the following video!

This video covers the R-2R DAC architecture. Digital-to-analogue converters based on an R-2R architecture have the advantage over string DACs in that they require fewer resistors and switch pairs. Presenter: Sabrina Koffler

An R2R DAC (Digital-to-Analog Converter) is a type of DAC that converts digital signals (binary numbers) into analog signals using a resistor ladder network. The term “R2R” refers to the specific configuration of resistors in the ladder, where “R” is the value of the resistors, and “2R” is double the value of the resistors. This setup creates a precise and consistent conversion of digital signals into analog voltages.

Key Components and Functioning:

  1. Resistor Ladder Network:
    • The core component of an R2R DAC is a series of resistors arranged in a ladder-like structure. This network consists of resistors of two values: R and 2R.
    • The resistors are arranged in such a way that each bit of the digital input controls a switch that either connects to a reference voltage (typically the power supply voltage) or to ground.
  2. Binary Weighting:
    • Each resistor in the ladder is associated with a bit in the digital input. The most significant bit (MSB) has the highest weight, while the least significant bit (LSB) has the lowest weight.
    • The combination of switches connected to the resistors creates a weighted sum of the reference voltage, resulting in an analog output that corresponds to the digital input.
  3. Operation:
    • When a digital signal is input into the DAC, the corresponding switches in the resistor ladder network are activated.
    • These switches control the current through the resistors, creating a voltage at the output that is a proportional representation of the digital input.

Advantages of R2R DACs:

  1. Simplicity and Cost:
    • The design is relatively simple, consisting mainly of resistors and switches, making it cost-effective.
  2. Precision:
    • The precision of the analog output is determined by the accuracy of the resistors. High-precision resistors can result in highly accurate DACs.
  3. Scalability:
    • R2R DACs can be easily scaled to handle different resolutions (number of bits) by adding more stages to the resistor ladder.

Disadvantages of R2R DACs:

  1. Resistor Tolerance:
    • The accuracy of the DAC is heavily dependent on the precision of the resistors. Any deviation in resistor values can lead to errors in the analog output.
  2. Power Consumption:
    • At higher resolutions, the resistor network can consume significant power, especially if low-value resistors are used.
  3. Switching Speed:
    • The speed at which the DAC can operate is limited by the switching time of the resistors and the associated parasitic capacitances.

In summary, an R2R DAC is a fundamental component in digital-to-analog conversion, valued for its simplicity and precision, making it widely used in various applications.

Auditions began! Enjoying the Music with Fantastic Companions…

The RT-Audio R2R Multibit DAC Orpheus (as the complete model name) was the second battery powered converter we received for reviewing, from the experienced designers mr. Tsvetan Tsenko & mr. Ivaylo Ratzov duo of Bulgaria. A few years ago, we also had the opportunity to conduct an interview with them, here is the link for further reading: [RT-Audio Design Interview 2020] . Of course, R2R was a welcome new visitor in my home. Taking notes for over five months (!) on various systems, then returning mainly on two of my beloved amp/speakers combinations (scroll down this page to get a snapshot), it enabled my rig to perform sensually. Moneywise and ‘sonicwise’! I consider it a great investment. Yet it did not take longer than seven or eight days between the time switching systems, that I wrote a review headline on my notebook: Category king for smoothness and a talented interpreter of realistic body of musicians! Hell, Yes.

I was pleasantly surprised by how well this DAC held its own on the audio rack, alongside much pricier models of amplification, speakers, and cabling. During extensive wav & flac files playback featuring well-recorded acoustic instruments, I consistently felt that RT-Audio’s presentation preserved the natural volume and character of each. This was especially evident when listening to classic jazz and some live acoustic guitar performances, which I appreciated the most. The sound was constantly full-bodied, though not quite in the same dynamic league as the five-figure digital sources resting beside it—something that seems entirely logical. Nonetheless, I was impressed equally by the solid, woody, and organic bass it reproduced.

Upon revisiting the same recordings, I noted that the RT’s R2R Multibit DAC delivered soundstage width, height, and depth with remarkable authority, along with details. I couldn’t help but smile when I noticed that this model was the most affordable among the mid-priced digital components in my setup. Despite its lower price, exceptional performance was ‘there’ without requiring an expensive audiophile AC power cable, which can often drive up the cost of a digital front-end. The midrange was on the creamy and rich side, and the high frequencies, though not as analytical as the best of today’s 3K category detail & transparency digital champions, were still satisfying.

After some time, I decided to switch out the interconnect cables to see how the unit would respond in different copper or silver models. Unfortunately, this wasn’t a happy experiment, as the RT-Audio DAC clearly shouts it deserves only the best quality cables—specifically, top-notch silver ones. Sonically speaking, this Bulgarian-made model is quite unique. Connected to my beloved Tsakiridis Devices KT-90EH-based single-ended Class-A Theseus integrated amplifier (Ultra/Custom Edition) and various silver or silver-plated interconnects, the sound leaned towards more analytical but still stress-free character. Instruments like the acoustic double bass, violin, and cello had an especially seductive weight and timbre, but also a great sense of space around each. Additionally, when paired as the source with older Conrad-Johnson solid-state amplifiers and the latest two-chassis McIntosh preamplifier, this (also) two-chassis battery-powered overachiever produced a slightly laid-back, yet big and colorful soundstage that carried a subtle touch of romanticism—whether you like it or not. Whether it’s silver or copper in the interconnects.

For instance, using expensive Audio Note AN-V Silver interconnects, the RT-Audio R2R DAC maintained the same expansive soundstage and buttery-smooth, full-range transparency that initially impressed me. It only slightly lost some of the punch, liveness and brightness that my self-made VdH Fusion interconnects added to the sonic table. The sound remained as rich in the lower frequencies, though the articulation seemed even more refined. Of course, it’s difficult to draw definitive conclusions after moving the RT-Audio DAC from Magnepan 30.7 speakers with solid-state components to the ProAc and Porfyra Audio setups plus tubes. However, what I last heard with the ProAc speakers in my room—paired with different speaker cables and amplification components—came close to rivaling the best, smoothest, and most ‘analogue’ sounding solid-state digital sources available for up to six thousand euros.

Listening to music through -generaly- the RT-Audio DACs with battery supply often brings me such joy that I’ve lost hours of sleep, staying up until the early morning, especially when taking notes on classical music. Cliché or not, it must be stated again: RT-Audio sources can truly relax you with the right setup, seducing you with their stress-free warmth and harmonic precision rightness. The more time I spent with the brand-new R2R battery DAC, the more I was captivated by its lush presentation. I recalled Salvatore Accardo’s legendary performance of Paganini’s concertos for Deutsche Grammophon, including the complete violin concertos recorded with Charles Dutoit and the London Philharmonic Orchestra—a majestic hour-and-a-half of musical brilliance (before switching to heavy metal!). Following that, I played some hot blues albums by Gary Moore and Stevie Ray Vaughan, which also sounded magnificent. I even dared to compare the RT-Audio DAC on the big ‘Maggies’ 30.7 system with the Greek-made Ideon Audio Absolute flagship DAC. That was a bold move, but my curiosity was quickly satisfied. As expected, with a price tag nearly ten times that of the RT-Audio R2R, the Ideon excelled in analysis and soundstage detail. Its sound was what we call more vivid & natural, creating a vast and seamless soundstage with impressive dynamic range, making the flagship planar loudspeakers more precise, lively, and detailed than any other competitor. In comparison, the RT-Audio R2R’s reproduction of the violin and orchestra was sweet and organic—enough to captivate any audiophile or music lover who’s content with, let’s say, 85% of the detailing and resolution of a five-figure solid-state digital to analog converter. Switching to blues and electric guitar masters, the R2R presented the recordings with impressive body and soundstage height, though with less attack and drive then the ultra talented ones. The lushness and tangible size of musicians playing right in front of you was aesthetically remarkable, so you can expect your favorite live and rock recordings to sound massive and never sterile.

Moving to Elgar’s Cello Concerto ripped from XRCD format, a highly dramatic and powerful piece that demands a system capable of handling complex dynamics, the RT-Audio R2R managed it -again- smoothly. However, it -again- couldn’t quite match the performance of flagship models in spatial information. While maintaining its tonal and harmonic character with slightly more colored and lush sound than the Ideon’s Absolute model, RT placed me mid-hall in the concert, with the orchestra seated well behind the speakers in a deep and wide relaxing soundstage. This is another aspect that I always adore when experiencing a concert hall performance. There wasn’t a hint of added brightness; in fact, I would categorize it among the slightly darker-sounding digital sources. At this point, let me be clear: The USB cables significantly impacts the DAC’s performance. While I’ve traditionally preferred Supra USB cables for their excellent value, this time the Nordost Blue Heaven USB cable revealed the highest level of precision and vividness. Pricier digital sources may have offered more tonal shades and sharper, more vivid textures, but listening with the RT-Audio felt more like riding in a luxurious Mercedes-Benz rather than a Lotus (sometimes on rough roads). If you’re looking for a more dynamic presentation and want to extract every last bit of resolution the R2R can deliver, I recommend switching to silver or silver-plated interconnects without breaking the bank, like those USB & RCA from Nordost or old-trusted Van den Hul mid-range line, as we did. This brings you one step closer to perfection.

Compared to our reference and resident DAC, the Porfyra Audio, which costs up to €7,000, the RT-Audio Battery R2R DAC offered a distinct listening experience. The Porfyra, a limited edition design featuring 2x6SN7 tubes and inspired by the Audio Note DAC philosophy while utilizing ESS-Sabre chipsets, excelled in several areas. It provided sharper image focus, richer tonal color, greater clarity and detail in the high frequencies, and a slightly deeper soundstage. Both DACs positioned the soundstage behind the front plane of the ProAc and Magnepan loudspeakers. However, the RT-Audio Battery R2R stood out in terms of image size, smoothness, and a mellowness that led to a completely stress-free listening experience, as expected from a well-designed battery-powered DAC. The Porfyra tubed DAC (Greek-made), though in the next price & performance league, could appeal to more audiophiles by offering greater insight into a great music production while maintaining higher resolution. It achieves this without sacrificing the size and immersive soundstage typically associated with tube equipment. In terms of overall sound quality, I could easily live with either. Despite the Porfyra Audio being 2.5 times more expensive, offering more harmonic richness and bloom, the RT-Audio was warm, rich, and relaxed, stable when switching from classical and operatic works to rock. It created a beautifully woven tonal palette, only surpassed by our two more expensive DACs nearby.

On Stevie Ray Vaughan and Albert King’s electric guitar masterclass, the RT-Audio played album after album with impressive tonal accuracy and nuanced detail. Its bass was tight, though not the most taut, with very good solid imaging for its price category. When I switched to operatic highlights from Mozart’s TELARC recordings of The Magic Flute, The Abduction from the Seraglio, and Don Giovanni, the RT-Audio maintained the same relaxed, cohesive, and well-balanced presentation. It offered admirable depth, height (often the most challenging), and width in the soundstage field. Every overture and solo vocal performance was captivating, making it difficult to stop listening. I was able to listen to nearly three hours of classic operas without feeling bored. This is a crucial advantage, especially for extended listening sessions. Despite its somewhat slower transient response and slight laid-back character, it never lost its engagement or musicality, which are very important factors when assessing a stable ‘musical’ performance. As for the epilogue, RT-Audio models may soon have a new distributor and showroom in Athens, which is exciting because we truly admire their work and, most importantly, their sound.

Conclusion

Over an unexpectedly lengthy reviewing period, I noticed that I frequently jotted down adjectives like “big-sounding,” “glamorous,” and “attractive” in my listening notes because of the Orpheus R2R Battery DAC pairing with the magnificent older Conrad-Johnson solid-state amplifiers or recent single-ended Class-A Tsakiridis Devices Ultra models. Consistently presenting the musicfull essence to my ears, mind, and heart. The partening amplifiers didn’t add any ‘contra’ personality or coloration, so the RT-Audio Design DAC sounded seductive because music itself can be seductive and glamorous.

This converter is all about elegance, finesse and boldness, ejecting the last iota of the analytical and bright characteristics. This model’s sound delivers boundless joy. I recognize that I’m experiencing something exceptional when the equipment I’m testing prompts me to listening music free from any stress or harshness. This is especially remarkable given the friendly cost of a 2-chassis battery-powered 2024 model priced close to 2.600 euros (add shipping). So, this is exactly what the RT-Audio design has achieved this year with their new DAC & (don’t forget to mention) also battery-powered Phono-Stage. These are intriguing times.

RT-Audio Design R2R Multibit Battery DAC Orpheus Price: ~2.600,-€ + shipping

Currently on display & auditions at :

Διαθέσιμο προς επίδειξη στην εταιρεία :

ΗΧΟΕΠΙΛΟΓΗ

 

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