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Master wordclock - gives added depth, width and spatial 'glory'.

13th January 2021

MUTEC REF10 SE120 by Jules


I have long enjoyed using a Mutec MC3+USB digital signal reclocker to reclock the USB signal from my laptop before it gets to my DAC .

The benefit of that is increased punch on drums, stereo width and clarity. I was using a 5 meter long USB cable and it was reassuring to get the signal ‘polished’ before it got to my DAC (full review HERE).

Mutec sent me their newest product - the REF10 SE120. It is a 10M master word clock (it outputs 10m word clock). Not all DACs have an input for a 10M word clock input though! Luckily, the MC3+USB does and it can ‘split out’ multiple 75 ohm or 50 ohm word clock BNC outputs that DACs and other equipment generally do accept.

Also, digital signals exiting an MC3+USB that is attached to a REF10 SE120 - such as TOS optical SPDIF, COAX SPDIF and AES/EBU - will all benefit from the attached master word clock.

I have done word clock shootouts back when I ran my own studio (Prism, Cranesong, Rosendahl, Benchmark, Digidesign) and had an idea of what I should listen for.

The chain I set up was:

  • Qobuz steaming: 41k/48k/88.2k/96k/192k files (mostly all at 24 bit) via Arualic Aries G1 streamer - USB out to Mutec MC3+USB - with Mutec REF10 SE120 external master clock attached via 10M BNC input cable
  • Grace M903 DAC (receiving AES/USB digital from MC3+USB) (also tested with Mytek 192-DSD DAC)
  • ADAM A5x speakers & sub

On the front panel of the MC3+USB I was able to A/B toggle between MC3+USB with AND without the REF10 SE120 Master Clock.

Without - same great sound I have been used to for the past few years.

With - REF10 SE120 - the improvement was quite dramatic.

I can describe it as added ‘glory’.

To explain, it’s my personal experience that a good word clock improves the audible depth of reverbs and an ability to ‘see into’ mixes’, as well as improved drum punch and overall mix clarity. I have heard this in my own studio. It can assist you in hearing details of reverbs you are adding. With the REF10 SE120, the sound from the speakers didn't just seem to be left and right - there seemed to be a sudden, new dimension, namely - height. It seemed to create a semi circle between the speakers that felt about 4 or 5 feet tall. It was eerie/spooky!

MUTEC REF10 SE120-drawing.jpg

The better the word clock, the better ‘locked’ and solid the reproduction of left / right spatial effects, or stereo source elements (like stereo mic signals) are. So in my listening tests albums like Roxy Music’s ‘Avalon’ - which have a lot of AMS or Eventide harmonizers in use and very profound reverb - or classical choral albums recorded with a stereo pair of mics in a church, the sound was upgraded. The wide stereo/spatial elements sound ‘more glorious’ and a byproduct of that is also an eerie, 3D ‘height’ and aded spatial ‘depth’. You could hear the ‘reverb cave’ in mixes better. It made me want to put some old Frank Sinatra on to hear the Capital Records Studio echo chamber!

My theory: I feel when producers and mix engineers add reverb and spatial effects or use stereo mics in an impressive recording space they WANT that to translate as amazing-sounding on playback in peoples homes. A low jitter master clock applied to digital audio playback assists this goal.

Christian at Mutec told me he carefully selects individual components and tests them for best jitter performance. Each “Special Edition” model of the REF10 doesn’t leave his workshop unless it meets his personal standard.

I did a lot of back and forth A/B testing with and without a master clock and I suggest anyone experimenting with adding a master clock does the same. If it doesn’t sound better - don't consider using it. (It may be that your DAC’s jitter can't be improved on!) This is something that needs to be judged carefully within your own set up - and with ears, not eyes. It can also be helpful to get someone in to help judge the difference with you - or do the A/B switching so you can listen ‘blind’ (I enlisted the help of a 19 year old relation). I think it’s also worth noting that in general converter manufacturers will state that their jitter reduction is adequate and external clocking is unnecessary - and that's fair enough. But this is where A/B testing is the only way to tell if external word clock will be of sonic benefit or not. A master word clock is for many a luxury item but one that should be considered by people wanting the very best they can get from their system.

For measurement fans, each Mutec REF10 SE120 comes with its own jitter test graph/certificate. (However, jitter measurement falls outside my scope of understanding so I won't make a comment on that!)

I can recommend this paired with an MC3+USB for supercharging a hifi DAC or for providing a master clock signal for a recording or mastering studio.


  • 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: 2.5 x 10-13 (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

Attached Thumbnails
MUTEC REF10 SE120-e76b3bb1-135b-4e3b-8601-62257e6beca2.jpg   MUTEC REF10 SE120-img_3666.jpg   MUTEC REF10 SE120-drawing.jpg  
Last edited by The Press Desk; 14th January 2021 at 05:36 PM..


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