The MUTEC REF10 is an audiophile reference master clock generating 10 MHz signals with industry-leading low phase noise (i.e. jitter) to significantly improve digital playback systems. As the conductor of your digital audio orchestra at home, the REF10 will inspire you with unheard-of clarity, graceful dynamics, and pure music. It is the most flexible, most compatible 10 MHz clock on the market allowing you to spend less time worrying about integration and leaving you with more hours to enjoy blissful playback.

Unlock a more dynamic, more transparent sound stage with exceptional spatiality and level of detail, free from any digital blur. For all music enthusiasts reaching for the pinnacle of signal purity, audio quality, and clock precision, the REF10 is the must-have expansion to conduct your digital playback chain.

Features:

• Audiophile 10 MHz reference generator with industry’s lowest phase noise
• Improves and enhances compatible DACs, audio re-clockers, music servers, and master clocks
• Engineered around a handcrafted, ultra-low phase noise OCXO made in Germany
• Generates a very high slew-rate square wave signal for superior lock precision compared to the sine wave signals used by competing brands
• Provides simultaneous reference outputs with 50 and 75 Ω impedance for maximum compatibility with clocks and DACs by other manufacturers
• Eight galvanically isolated, individually switchable BNC clock outputs
• Revolutionary, sub-Hz optimized, lowest noise power supply for every circuit section
• Integrated, highest-quality international linear power supply
• Highly efficient power line filtering
• Intuitive user interface with noble aesthetics
• Rack-mountable with optional mounting brackets for studio use (2 RU)

The Story of the REF10

Currently available digital converters, master clocks, and audio re-clockers perform acceptably when reproducing or processing digital audio. Even so, we at MUTEC felt that existing solutions fall short of delivering the full potential of audio productions. In our commitment to advancing the state of the art and science we set out to investigate the possibilities to further enhance the performance of digital audio systems. To do so, we recruited one of Germany’s most renowned RF engineers to join our R&D team. Together we developed a master clock generator with a technical performance beyond what we thought could be possible. The effects of the technical performance were then verified by a group of experience audiophile beta testers to ensure that the high-end performance translates to best-in-class sound.

The final result of our extensive efforts is the REF10: a superior 10 MHz reference master clock and our first Empyreal Class product combining uncompromising engineering with the beauty of simplicity and the utmost clock precision.

Debunking the "Atomic" Myth

Our research has shown that the high clock stability of so-called "atomic clocks" based on a rubidium or cesium oscillator is limited to the long-term time domain. This long-term stability refers to the amount the absolute clock frequency (10 MHz, or 10 million cycles per second, in this case) drifts over time. While this long-term stability may be useful for some telecommunications applications, it is essentially irrelevant for digital audio purposes. Ultimately, it is the timing from one sample to another as a digital audio stream is transferred from one device to another that needs to be as precise as possible for best sound quality. Fluctuations in short-term stability are measured as jitter or phase-noise and are central to the audiophile performance of any digital audio device.

In contrast to these "atomic clocks" then, the REF10 is engineered around MUTEC's handcrafted, oven-controlled oscillator (OCXO) made in Germany, featuring highest clock stability in the time domain relevant for audiophile digital audio performance.

Exceptional Design

A well laid-out main power supply constitutes the basis for exceptional high-end products. To meet this requirement, we specifically designed for the REF10 a dual linear power supply based on a German made toroidal transformer. It provides a dedicated transformer winding for the sensitive OCXO that is completely isolated form the surrounding circuit. Networks of lowest-ESR (equivalent series resistance) capacitors made by Panasonic ensure best interference suppression for the supply voltages. Hereafter, sub-Hz optimized, lowest-noise voltage sources arranged in multiple stages independently supply every part of the circuit to avoid mutual interference. However, for the heart of the REF10, MUTEC’s handcrafted OCXO, we had to go even further. We developed a dedicated power source of such incredibly low noise that even our engineers themselves were amazed by the noise figures and the resulting oscillator performance we ultimately achieved. Consequently, we then developed unique ultra-low noise clock distribution and amplification circuits, which successfully transfer the oscillator’s reference signal to the REF10’s eight outputs with virtually no losses.

Phase noise of the REF10 as a function of frequency

Based on our knowledge of the importance of a clock signal’s rise time (steepness of the edge) for the audio performance, we chose a very high slew-rate, lowest ripple square wave signal for the REF10. In contrast to the low slew-rate sine wave signals used by competing brands, this leads to superior lock precision and therefor minimized jitter at the receiving end. As a result, connected devices like DACs (D/A converters) and audio clocks will sound even better.

The exceptionally high slew-rate, lowest ripple square wave signal of the REF10

An often discussed topic among audiophiles are the negative influences of RF (radio-frequency) interference in digital audio. In order to shield the REF10 from such RFI and other interference we are placing the circuit boards in a 1.5 mm thick steel enclosure, which isolates the sensitive electronics from outside electrical disturbances. We intentionally refrained from using an aluminum case popular with other manufacturers. An aluminum case would perhaps have lent a more esoteric look to the REF10, but it would have seriously degraded the shielding characteristics allowing RF interference to directly increase noise and jitter of the clock signal.

RF interference can also enter the circuitry via the mains power connection. To avoid an power line interference as best as possible, we have equipped the REF10 with one of the best premium, brand-name power entry modules currently available. This module offers enhanced low frequency filtering and superior EMI immunity. As part of its mechanical design there are no open, unfiltered power cables inside the unit unlike many other products on the market.

To especially minimize the susceptibility to hum caused by ground loops we have designed the REF10 with galvanically isolated output stages. Every BNC reference clock output can be switched off individually so that only the currently desired outputs for a given setup need to be active. This feature further adds to our measures to keep mutual interference and system load as low as possible.

One Clock to Rule Them All

The REF10 is the most flexible, most compatible 10 MHz clock on the market allowing you to spend less time worrying about integration and leaving you with more hours to enjoy blissful playback. Due to its ultra-low noise characteristics and its unrivaled flexibility the REF10 can enhance the audio quality of compatible D/A converters (DACs) and re-clockers, music servers, and audio clocks to the highest possible level. It is the perfect match and ideal upgrade for MUTEC's 10 MHz ready products like the MC‑3+ and MC‑3+USB Smart Clocks, as well as the iClock and iClock dp.

Eight simultaneous clock outputs at both 50 and 75 Ohms impedance allow you to use the REF10 in combination with not just MUTEC products, but also 10 MHz compatible products by all other third-party manufacturers.

10 MHz Compatible Products Currently in Production:

Disclaimer: Compatibility of the REF10 with the above listed products is assumed based on the specifications published by the respective manufacturers and subject to change. MUTEC is not liable for compatibility issues with third-party products operating outside of industry standards.

With MUTEC to "heavenly" sound!

Within the Empyreal Audio Class series, MUTEC offers special digital audio devices dedicated to the demanding users of top-quality hi-fi stereo systems. These unique products benefit from MUTEC's decades of expertise in the field of professional studio technology. This knowledge flows into the development of audiophile tools that have outstanding sonic abilities.

A MUTEC Empyreal Audio Class component always focuses on features most relevant for authentic sound reproduction in a high-end audio system. Decorative accessories or cluttered front plates are alien to these devices. Therefore, the operation is designed to be user-friendly and convenient. On the outside, the series is characterized by functionalism combined with simple elegance. Internally, the highest level of technical precision can be found based on best available materials. Both aspects support the conceptual goal of the Empyreal Audio Class: pure concentration on what is technically essential.

All MUTEC devices of the Empyreal Audio Class series represent long-term investment because of their highest quality at all levels - of course "Made In Germany".

Interfaces

• 2 x 10 MHz reference clock BNC output, 50 Ω terminated, unbalanced
• 6 x 10 MHz reference clock BNC output, 75 Ω terminated, unbalanced

Signal Format of all Clock Outputs

• Square wave, 10.000 MHz, 2 Vpp, 50:50 duty cycle

Clock Generation

• Type: 10.000 MHz ultra-low noise oven-controlled crystal oscillator
• FQ stability when shipped: < +/-0.01 ppm
• FQ stability vs. temperature range: < +/-0.01 ppm within -20 °C to +70 °C (-4 °F to +158 °F)
• Short term stability (Allan deviation) at Tau = 1 s: 1 x 10-12 (typically)
• Aging after 30 days operation:
  < +/-0.0002 ppm (per day),
  < +/-0.03 ppm (1st year),
  < +/-0.2 ppm (10 years)
• Warm-up time at +25 °C (+77 °F) : <5 min

Phase Noise, Measured at REF10’s Outputs

Phase noise of the REF10 as a function of frequency

Jitter Performance, Measured at REF10’s Outputs

1-100 Hz: ≈ 22 fs

Jitter performance of the REF10

Disclaimer: All measurement figures represent average values. Minor production related deviations will be expected.

Power Supply

• Type: internal dual linear power supply
• Input Voltage: 90-125 V / 200-240 V, 50-60 Hz
• Power consumption: 12 W during oscillator warm-up, 8 W nominal operation

Mechanical Details

• Cover size/material/color: 196 x 84 x 300 mm (W x H x D, without connectors and case feet), 1,5 mm steel, black powder-coated
• Front panel size/material/surface/color: 198 x 88 x 8 mm (W x H x D), aluminium, anodized incl. anodic printing or silk screening, aluminium- or black-colored
• Weight: approx. 4350 g (9 lb, 9.5 oz)

REF10 Order Information

• Front aluminum-colored: Item No. 8015-105, EAN Code: 4260342461044
• Front black-colored: Item No. 8015-106, EAN Code: 4260342461051

User Stories

• Jaap Veenstra, www.alpha-audio.net, Netherlands
  The differences are the same for each track. And also with every genre. There is less edginess, more palpable acoustics (more insight into the recording and the acoustics of the studio) and the space grows, with the separation between the instruments being more clearly established. The result of these dots on the i is that we want to listen to more music. And then when we go through our library, it turns out that less pleasant recordings are much more palatable. [...] Because of the reduction in sharpness, it is much more pleasant listening to these non-audiophile recordings. Fortunately, it is also true that beautiful recordings are even more beautiful. So it’s not that it camouflages things. Because in Massive Attack’s Teardrop we just hear new things. And also in the album Heligoland we hear new things in tracks. Once again, it shows that Massive Attack pays unprecedented attention to their recordings. You just keep discovering things. Very cool!
  Read the full review

• Edgar Kramer, www.soundstageaustralia.com
  The REF10 showed its muscles more overtly and is befitting of the best high-end systems. Again, there were no omissions, degradations or noticeable depreciations from the music. On the contrary, it provided a worthwhile extension to the sonic picture, especially in terms of soundstage depth which stretched further behind the speaker plane. Micro-detail was also somewhat refined and sieved through with purity.

• Jack Corneveaux, France
  The REF10 is been running since Monday Afternoon and sounds wonderful--an amazing improvement in sound quality!  Even though I have a PS Audio DSD Sr with the PS Audio PMD CD player, I have remained pretty much an analog bigot. So a few months ago, on a whim, I installed the Bridge II on my DSD and set up Roon with Qobuz.  After a little investigation, I came across the EtherREGEN which was a marvelous improvement and then your REF10 which added yet another significant improvement in sound quality level. Bottom line, my analog bigotry has seriously receded!

• Ruud Jonker, www.hi-fi.nl
  It remains to be said that the MUTEC MC‑3+USB and the REF10 are actually products for the professional market. However, it is also clear that reducing jitter and blocking as much as possible interference signals that mix with the audio signal via digital connections contribute to higher sound quality. [...] It was noticeable that there is more peace in the sound image. [...] The overall result is a more realistic and natural sound. It should be clear that the outcome will be stronger if the REF10 is also connected.
  Read the full review (Dutch only)

• Torbjörn Prodenius, Sweden
  I received the REF10 and got it hooked up to my two MC‑3+USB and the sound is amazing. Better transients, transparency, micro-dynamics and a tonality that is great, more like real instruments. Good to know that I now can get the most out of my system!

• Leonard Fong, Horus Studios, Singapore
  I had an Antelope Atomic 10M before, but I did not hear the dramatic difference of the external clocking compared to the REF10. The immediate effect I heard is an improvement in size, width, depth, details of the reverb & delay tails. The vocal pops forward and the overall level is louder than without the REF10. It is louder and yet, still dynamic. The low-end is insanely tight and controlled! The songs I played back sound like a remix. I love it! It is a life-changing piece of equipment for my work.

• G.H., Germany
  The first impression was already very positive. Now, after about 150 hours, I can confirm the initial perception without reservation. I think I can hear that the device has got even better over time: Both instruments and voices sound absolutely natural and analogue, like a good vinyl record reproduction. The spatial representation is phenomenal.

• Srajan Ebaen, 6moons.com
  At what price point should audiophile digital become impervious to external reclockers? From our hardware, even the €9000 COS Engineering D1 wasn’t. I wish it were different. But until it actually is, external reclocking by way of MUTEC’s MC‑3+USB and REF10 remains a legitimate audibly effective solution.
  Read the full review

• Beat Brüderlin, Germany
  With the MC‑3+USB Re-clocking device, and in particular with the REF10, for the first time digital audio is on par with analog audio. Before that I always had the impression that digital audio masks important details. As a consequence also spatial perception was negatively affected. With the REF10 these problems are a thing of the past.

• Jay Luong, USA
  There’s something so ... faithfull about what the REF10 does. It removes the noise and confusion entirely and brings life to your to your digital library. If you want to hear the best of what digital audio has to offer. Get a MUTEC REF10 – pronto.
  Read the full review

• HiFi Excellence, Sweden
  It did not take more than a few minutes of listening to realize the superior performance of the MUTEC REF10 compared to the Cybershaft Ultra Precision (OP13). The soundstage came alive like never before, spatial information became very real, and voices in particular sounded frighteningly realistic. Also, micro-details from instruments and ambient information was heard like never before. Bass response was exceptional. Amazing that all this can be achieved just by adding a very accurate master clock. In a visual analog, the Cybershaft Ultra Precision would provide an HD (720p) image and the MUTEC REF10 would render 4K image quality.
  HiFi Excellence

• Simon Goodall, USA
  As a long time dCS stack owner (first Paganini, currently Vivaldi V2) I’ve been a convert to the value of dedicated clocking systems. The dCS clocks are pretty darn expensive boxes and while they (like all dCS gear) benefit greatly from upgrading power cords, 75 ohm interconnects and feet I had never really thought that adding a further reference clock would bring any benefit. However […] I wondered if I’d been mistaken and if an external 10 MHz reference could add even more to my system. I've now had the REF10 in my system for several weeks and frankly it's probably the first time I'm really beginning to believe that digital can give my analog setup a real challenge -- with how I have it now I feel as if I'm hearing two increasingly similar takes on the same absolute -- digital converging on all the best in terms of space and realism I've found in analog, while the latter […] getting the speed stability and rhythmic integrity that digital can do so well.
  Read the full review

• Atilla Gülsen, Greece
  Connected to three MC‑3+USB the REF10 adds an extreme wealth of additional details to the music and the spatial information. The highs are much more present with a huge gain in smoothness. The bass response on the other hand is much more precise and packs more punch. Overall, the music playback now almost magically extend beyond the speaker plane. Words can't really describe the huge compliment I'd like to express to everyone at MUTEC. The REF10 is truly a groundbreaking experience for me. All the best wishes to the team and company.

• Jan Novello, USA
  I find now, this is the sound system I had hoped for, demanded and dreamed of. The REF10 is the piece of equipment which has taken it to that next level (after the MC‑3+USB). It has accomplished two very important improvements in the sound of my system: it maintains the integrity and focus of instrument and voice from source point, and very importantly while keeping that focus/integrity, moves it further into the listening room than before. Every individual detail of sound emitted has its own texture and shape which wasn’t there before. The Focal speakers are a different speaker now, much more dynamic and better at both sound-staging and imaging. Bass also, is improved and refined. Other reviewers claim the emotion of the musician is more apparent. I find this to be true. Previously I was listening to the music, now I am part of it, as it engages on physical as well as intellectual level.

• Kwok Yan, Hong Kong
  As soon as you set up the REF10 with the MC‑3+USB it's like you're in a totally different world: no more noise, lower distortion, better dynamic range, extended frequency response, and improved details.
  Watch the video review

• Seunghyun Chung, South Korea
  We were amazed by the improved resolution that we got compared to any clock or reference generator before. The clarity of the sound and the spaciousness of the stereo image upgrade our existing DAD AX32 converter. No matter what digital equipment you are using, the REF10 and iClock will no doubt provide a superior sound.

• Paul M., USA
  To my ears and in my system and in my room the overall effect of adding the REF10 was to create a much more natural, refined and realistic sound. Nearly all aspects of music were improved for me even dynamics, sound stage localization, and depth. It is basically a more engaging overall presentation with subtle notes and decay being more apparent with a very realistic tonal balance. Musical threads by individual instruments are now very easily followed. Music is much more like a living, moving tapestry. I now listen more to the music and less to the equipment. This is the highest praise that I can think of.

• Dr. Roland Dietl, Hifistatement
  Matched with the right players the REF10 will lead to an exceptional listening experience. It's incredible how much this clock adds to the sound fidelity - you have to hear this yourself!
  Read the full review

• V.D., France
  I have compared in my fully digital system the REF10 with the Stanford Research FS725 Rubidium. To conclude: the REF10 delivers a more realistic sound than the FS725. That means cleaner note attacks, more harmonic richness, more separation between instruments and above all, more live details about the recording environment. In other words, I'm very happy with the REF10!

• Pierre C., Switzerland
  Adding a REF10 in the chain is about giving the supplement of emotions/soul which is sometimes lacking when the transparency is so good that you can hear every defect in the recording. The micro-vibrations rendered by this system with the REF10 give to the noise of the fingers on the strings of a violin all their meaning, as well as the micro-variations in the voices give them a texture which makes them sound, not only perfect, but real. Hats off for Mr. Peters and his team, who have made it exceptionally once again.

• Sean Lee, SOtM Audio, South Korea
  We have tested the MUTEC REF10 together with our tX-USBultra, an USB audio regeneration interface including the sCLK-EX12 internal reference clock module, with a 50 Ohms BNC cable made by ourselves. After hook up everything we were immediately amazed and got really satisfied with the enhanced sound quality of this combination of audio gear. While longer listening to our favorite songs we became really happy to experience this significantly improved sound quality and to have this well-engineered master clock now in our set-up. We highly recommend the REF10 to everyone who is looking for an absolute high end 10 MHz master clock device.

• Harald Wittig, Germany
  I didn't believe it was possible, but everything sounds better yet with the REF10. The music seems more open, the spatiality significantly gains in width and depth, and the localization of individual sound sources is now even more precise. The sound is not as hard and digital, but significantly smoother and (yes, indeed) more audiophile.

• Fabrice Alonzeau, France
  The MC‑3+USB is already a very good addition to my system but feeding it with a 10 MHz clock signal of the REF10 causes an outstanding improvement in sound quality, like playing in another league! With the REF10 in the chain, the sound quality is more open, more realistic. It is as if more acoustical elements are coming out of the speakers, I would say like a holographic sound-experience.

• Cheon Hoon, South Korea
  I really like the feeling of being able to deliver precise monitoring and the responsiveness to delicate processing. The 10 MHz clock signal of this amazing instrument gives presence and clarity to the depth of the sound, which allows for even more precise processing.

• Michael Gray, USA
  After the REF10 arrived, I immediately connected it to my cascade of 4 x MC‑3+ and let the system run-in a while. As per the other customers who have already commented, the REF10 opens new sonic worlds from old CDs. Through my STAX earspeakers, I can really hear into the music in its performing space. It's often uncanny to audition recordings from 60 years ago which sound as if they were made yesterday. For the funds invested in the MUTECs, I think I've gotten a pretty good deal. Very (!) many thanks for speeding the REF10 to me - and special thanks to you and the engineering crew. Keep it up!

• Matt Colton, Alchemy Mastering London
  The REF10 lends a noticeable tightness to the bass and an increase in presence, but all in a very musical way. It makes everything sound both louder and more dynamic, which for a mastering engineer is the holy grail. Compared to other 10 MHz reference clocks we tried it was definitely smoother and more elegant sounding.

• Roy F., USA
  After just 24 hours of continuous playback with the REF10 and my SOtM sCLK-EX clock board, the music has really begun to open up. Everything is smoother, clearer, cleaner, crisper, more dynamic and more dimensional. I'm sure the sound will continue to improve with more time but this is already simply incredible! The sCLK-EX clock board and your REF10 are truly a match made in heaven. Congratulations on building such a wonderful master clock!

• Krit Poonsirivong, Thailand
  The REF10 has taken my system from what I thought was very good digital playback to the level of reference music playback. The REF10 has added what I would categorize as real sound naturalness to the digital chain that thought was not possible. REF10 has taken out the digital sound out of digital. I would very much really highly and easily recommend everyone to hear the REF10 for themselves and I am sure they will be amaze at the all of the improvements. Great great job!

• Cyrus Komer, USA
  I am clocking a MUTEC MC‑3+USB running AES into a Devialet via roon. I am absolutely amazed by the REF10! I will simply say it has had the greatest effect on the sound of my system I have ever heard. The space between instruments, the high frequency detail such as the acoustics of the hall or studio, the limpid clear sound of the piano or the complex timbre of a violin are reproduced in a natural and unforced fashion that makes me feel I am at the recording session itself. I was impressed by the MC‑3+USB but I must say the REF10 is engineering at its very best- as a musician (pianist), it makes me forget about the gear and simply enjoy the music. My congratulations on a wonderful product!

• Kevin O'Brien, YourFinalSystem.com
  We have to say the REF10 made a very noticeable difference when we placed it in our chain. The difference in sound quality was immediate when listening to hi-res material. Our music now sounded as if the musicians were almost playing in the room with us. The REF10 was a very welcome addition to our system and it could very well transform your rig as well.

• Sung Joo Lee, CJ E&M Tooniverse, South Korea
  In the past, we used word clock equipment for other pro audio companies. Once we installed the MUTEC REF10 & iClock we were immediately impressed by the clear sound. Before I'de always been unhappy with the mid & bass frequency range, but after connecting the REF10 & iClock all of this was resolved. The clarity of the sound, the wider stereo image and the low-end resolution make the AVID MTRX main converter sound so much better.

• Guy Zilberman, Thailand
  As many others have pointed out, the REF10’s contribution—subtle as it may—is addictive. Of course, in terms of sheer value, the MC‑3+USB outmatches the reference clock with ease, but the REF10 puts on a finishing touch that music lovers would find hard to give up on, let alone ignore.

• Joao Branco, Portugal
  I've just added the MUTEC REF10 to my system. I never thought the overall sound quality would be so much improved with the REF10. I would say, more than 50% better! Thanks a lot and congratulations for your excellent product. What a great piece!

• Alexander Weiss, Netherlands
  You simply achieve more realism with the REF10. Everything sounds exactly as it should. And it’s a massive improvement to just the MC-3+ alone. I play acoustic (and electric) guitars and piano myself, so I know how things are supposed to sound in real life.

Web Discussions

• REF10 discussion in the "Computer Audiophile" forum

Reviews

• MC‑3+USB & REF10 review, by Edgar Kramer, www.soundstageaustralia.com
• MC‑3+USB & REF10 review, by Ruud Jonker, hifi.nl (Dutch only)
• MC‑3+USB & REF10 review, by Srajan Ebaen, 6moons.com
• REF10 Master Clock – Digital Audio’s Heartbeat, by Jay Luong, Audio Bacon
• REF10 review, Dr. Roland Dietl, Hifistatement (German only)
• REF10 - the musical director, by Harald Wittig, Fidelity Magazin
• REF10 & MC‑3+USB review, by Kevin O'Brien, YourFinalSystem.com
• MC‑3+USB and REF10 review, by Felix Klostermann, bonedo.de (German only)
• Marvelously Clear Sound, by Ubukata Saburo, Phileweb and Audio Accessory (Japanese only)

Product videos

• In-depth review by Hong Kong based magazine FeverSound (Chinese w/ engl. subtitles)