Review: Mutec REF10 SE120 as external 10 MHz clock on Jay's Audio CDT3 MK3 transport

Al M.

VIP/Donor
Sep 10, 2013
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Greater Boston
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In connection with my previous Simaudio Moon 260 DT CD transport I had found the Mutec top 10 Mhz clock, the REF10 SE120, to be beneficial.

The Jay's Audio CDT3 MK3 CD transport is far superior to the Simaudio Moon 260 DT transport, see here for my initial impressions (post#613).

The CDT3 has excellent jitter specs of <1 psec -- a substantial part of its circuit is dedicated to reclocking. In comparison, jitter for the Simaudio Moon is specified at 115 psec (an Oppo has 800 psec jitter). The digital output from the Simaudio Moon had gone in my system through a Mutec MC 3+ USB reclocker, and more recently, through the Mutec MC 3+ USB fed and controlled by the Mutec REF10 SE120 as 10 MHz clock. This of course substantially reduced the jitter from the transport.

I must admit that the excellent jitter specs of the Jay's Audio CDT3 MK3 transport made me question if my Mutec 10 MHz clock still would make a difference, but this is the case. The phase noise of the Mutec REF10 SE120 is so vanishingly low that it still helps. When connected as external clock, the Mutec bypasses the internal OCXO (oven controlled crystal oscillator) of the CD transport.

From the Mutec website: https://www.mutec-net.com/artikel.php?id=1603308593

"With a phase noise value of < 120 dBc measured at 1 Hz offset from the carrier frequency of 10 MHz, the REF10 SE120 produces uniquely low jitter measured values of an average of <15 fs in the crucial measuring range between 1‑100 Hz."

See also the graph in below link: https://www.hifistatement.net/tests/item/2991-mutec-ref10-se120?start=3

(A measurement sheet like this comes for each individual unit received by a customer; mine looks very similar.)

And while my Mola Mola Tambaqui DAC apparently does its own internal reclocking as it upsamples to a very high speed data stream, it is not immune from incoming jitter in the digital signal that it receives (I assume few DACs, if any, are). In fact, a Mutec/Tambaqui set-up is featured here, with a streamer as source:


For removing jitter from the signal out of my Simaudio Moon 260 DT transport, which does not have an input for an external 10 MHz clock, I had used the following configuration:

CD transport > BNC cable to Mutec MC3+ USB reclocker, fed and controlled by external 10 MHz signal from the Mutec REF10 SE120. From the Mutec MC3+ USB the signal was fed via a second BNC cable into my Mola Mola Tambaqui DAC.

When switching to the Jay's Audio CDT3 MK3 I had initially kept the same configuration, and my first impressions (linked to above) were gathered listening that way.

Yet now, given that the CDT3 has its own 10 Mhz clock input, the simpler, and here tested, configuration is:
CDT3 directly fed by the Mutec REF10 SE120 > BNC cable from CDT3 to DAC.

The digital cable feeding the CDT3 from the Mutec REF10 SE120 is a Mutec PSC 50 cable (50 Ohm) via one of the Mutec's 50 Ohm outputs. While it is fortunately not very expensive in high-end terms, it has been measured to properly do the simple job that it is supposed to do, which is feeding a high quality 10 MHz square wave signal to the input, in this case the CDT3. Not any cable, not even any expensive one, is necessarily 10 MHz square wave ready (a different requirement from a 10 MHz sine wave, which a lot of other clocks operate with).

The 10 MHz input of the Jay's Audio CDT3 MK3 is specified as "50 to 75 Ohm". Initially I had used a Mutec PSC 75 cable (75 Ohm) via one of the Mutec's 75 Ohm outputs; a 75 Ohm connection from the 10 MHz clock is also used to the Mutec MC3+ USB. Yet after inquiry with Jay's Audio I was informed that a 50 Ohm connection was preferred. This is the above described connection that I used for the review. However, at this point I cannot confidently say that there is a significant difference in performance between using either the 50 Ohm or the 75 Ohm output from the clock into the CDT3. Admittedly, I have not done an in-depth comparison between the two options.

An active connection from the 10 MHz clock to the CDT3 is indicated with a small label "Ext.CLK" on the top edge of the LED screen of the CD transport, in the same size as for example "Repeat disc". Very nice.
 
Now on to some listening. Just as a statement upfront, the Mutec REF10 SE120 clock did not make a clearly audible difference on all music, in the context of my digital set-up, which is already very low in jitter to begin with, and of my system. However, as you will see, I find it very worthwhile for the kind of improvements that I heard, as in the examples described below.

I made sure that my impressions held up repeatedly and consistently on several different days; I am not a fan of reporting on subtle yet meaningful differences in sound and musical presentation in a casual manner.


Redman_Struggle_Continues.jpg

The album "The Struggle Continues" by Dewey Redman is an excellent recording on the ECM label (ECM 1225). On the funky 3rd track, "Turn Over Baby", Dewey's tenor saxophone has an incisive yet warm, rich, full sound. Without the clock the sound is still warm, but this is somewhat deceiving. Close listening reveals that the sound, despite the warmth, also has a slight dryness and is harmonically just not quite as rich as with the clock being active. This of course is relative; without the direct comparison you might not even notice the slight dryness with the Mutec clock left out of the chain (the recording is generous in tone to begin with). In the context used, the clock really is for maximizing an already excellent digital reproduction. -- The saxophone playing is also somewhat more incisive with the clock active.

After a stormy beginning, track 2 ("Love Is") features a very softly played saxophone solo of exquisitely mellifluous, buttery phrasing. Without the clock there is again a bit more dryness of tone, which makes for less of a buttery flow of the sax solo. As before, by normal standards the sound without the clock is still excellent, but with the clock active it is even better and highlights Dewey Redman's artistry even more.


Higdon_Concerto_Orchestra.jpg

Jennifer Higdon is one of the most performed living American composers of classical music. Her orchestral piece "blue cathedral" has been played all over the world 1,100 (!) times since its premiere 25 years ago, see:


Below are some impressions from listening to Jennifer Higdon's Concerto for Orchestra. I listened to the Telarc CD (CD-80620).

Here is a video of another, live, performance, showing the instruments played:


The slow movement (starting at 14 min in the video) begins with violins playing in the extreme high register. When soon after the violas start to play, it sounds more focused and more calm with the 10 MHz clock. The playing also sounds slightly quieter. The sound of the ensuing solo flute, further back on the stage, is surrounded by a lot of air. Yet with the clock active, there is even more air. The flute solo also sounds calmer with the clock, as well as more pure. It sounds more 'lonely' as well, fitting for the musical expression. The polyphony in three flutes that starts after another phrase for violas and lower strings unfolds even more serenely with the clock in play. The music in the piccolo flute that ends this brief section soars more cleanly and distinctly.

There is magic in the additional calmness brought to the described musical passage by the 10 MHz clock.

The second movement is written exclusively for strings, and the string textures are forging an intriguing equilibrium between luminescence and dissonance (as heard on the high-quality Telarc CD; the audio quality of the string sound in above video is relatively crude in comparison). Without the clock, the sound slightly shifts away from luminescence, which makes it flatter and more emphasizes dissonance. The result is a bit more pedestrian in texture than with the clock active.

Stravinsky_Persephone.jpg
Similarly, in part II of Stravinsky's colorfully textured oratorio Persephone (Stravinsky conducts Stravinsky; Sony SM2K 46 300), at 2:20, there are also string parts that are luminescent and somewhat dissonant at the same time, yet the tone is sweeter than in the Higdon concerto. Again, some of the luminescence is lost without the external Mutec clock, and the texture is flatter.

At 19:20 in the same part II there is an ensemble of collective solo strings, which accompanies the expressive speaking voice of Persephone with a soaring, floating texture full of life and delicacy. Some of that delicate filigree is lost without the external clock, the sound is "straighter" and less alive. As a consequence, the string texture loses the lightness of floating and with it, its beguiling magic.

After about 2 minutes into part I the chorus, here apparently a mix between female voices and children's voices, begins to sing. Its sound and texture are uncommonly beautiful and airy. Without the external clock the sound is less firm in its solidity, and at the same time its characterful and pronounced airiness loses some of its strength and clarity. The sound is softer and more veiled, and somewhat smaller in expanse.


Hahn_Ysaye.jpg

Hilary Hahn has recorded an album of the complete violin sonatas (DGG 486 4176), six of them, on occasion of the 100-year anniversary of the composer"s writing of these sonatas in July 1923. The album features spectacular performances and sonics; it was recorded in Hahn's favorite recording venue, the Fraser Performance Studio in Boston.

When listening to the vigorous beginning of the 2nd movement of the 5th sonata (track 14), the articulation of the violinist's playing is more palpable and fleshed out with the Mutec clock in the chain, and the playing is more nimble and alive. Without the clock, the musical articulation of the performance is slightly flatter and slightly less expressive.

Overall, with the clock inserted, there is a bigger, more energetic, bold, confident and open sound coming from the violin. Quieter passages maintain their character or sound even more refined.


Beatrice_Rana_Chopin_Beethoven.jpg

Beatrice Rana is an excellent young Italian pianist. Together with a friend, who had introduced me to her artistry, I had the pleasure to experience her playing live last year at Boston's Jordan Hall with its wonderful acoustics, in truly compelling performances. The piano on the CD (Warner Classics 5054197897658) of her playing Chopin's Piano Sonata 2 and Beethoven's Hammerklavier sonata (she played the latter also in that concert), has a warm, full sound. While that character is maintained with the Mutec REF10 SE120 feeding the CD transport, the insertion of the clock slightly increases sparkle on the notes, substantially increases articulation, and with that makes the music livelier.

As a result, the beginning of the scherzo of Chopin's sonata (track 2 of CD) sounds truly ferocious, while without the clock the music is slightly heavier and less agile, somewhat duller sounding and not quite as dramatic.

Increased articulation and sparkle of tone with the Mutec 10 MHz clock in the chain, apparently better timing and more organic and gripping flow are also beneficial in the Beethoven sonata, which receives a passionate and exciting interpretation. At the beginning of the scherzo (track 6 of CD), the now better articulated notes are more separated with the clock. Without it, they seem to slightly run into one another in lines that in comparison sound somewhat muddy. Micro-dynamics, the small volume changes as the phrases are shaped, are also better expressed with the clock active.

In the complex fugue of the last movement of the Beethoven sonata (track 9), the music with its diverse simultaneous strands is easier to follow with the Mutec REF10 SE120 in the chain. The notes blur less into one another, rather, they are presented in clean lines. Beatrice Rana seems a better musician with the clock in service of a more accurate reproduction of her splendid performance of the piece, and the music just seems clearer. The whole musical experience is improved to be more immersive and compelling. Isn't this what the high end is all about?

***

Finally, I'll give an example where the 10 MHz clock indeed does not make a difference anymore, unlike with the Simaudio Moon 260 DT, because the CDT3 is just so good already.

I had been listening to the configuration Simaudio Moon 260 DT transport > Mutec MC3+ USB > Tambaqui DAC, when I took notes on the differences with or without the Mutec REF10 SE120 feeding the Mutec MC3+ USB.

Here are my notes on the trumpet fanfares at the beginning of Stravinsky's opera "The Rake's Progress”:

"Here a spectral "fanning out" without the 10 MHz clock causes the sound to be both sharper and more diffuse -- again affecting the flow with smearing as well. With the clock in place, the sound is more controlled, temporally and timbrally, and focused."


It turns out that with the CDT3 I cannot hear a difference on this passage if the CD transport is fed the signal from the 10 MHz clock or not.

I have to say that in general the Jay's Audio CDT3 is so good that even without the external 10 MHz clock it sounds better and cleaner than the Simaudio Moon 260 DT de-jittered with the Mutec REF10 SE120 clock controlling the Mutec MC 3+ USB reclocker.

Yet the combo of CDT3 with external Mutec REF10 SE120 10 MHz clock is the icing on the cake. After hearing the meaningful differences that it brings to the music, I cannot imagine my system anymore without the Mutec clock in it.

I received my unit, and the Mutec cables for it, from Alex Crespi at UpTone Audio who recently became a Mutec dealer. The service that Alex provides is impeccable and he was very helpful with answering all my technical questions in depth and great detail. Few dealers will have such technical expertise and will engage with the customer as much as he does.
 
Listing of review system

System: Mutec REF10 120SE (10 MHz clock) > Mutec PSC 50 cable (0.75 m) > Jay's Audio CDT3 CD Transport > Empirical Audio Reference BNC digital cable (1.5 m) > Mola Mola Tambaqui DAC / Octave HP 700 preamp / Octave RE 320 stereo amp with Super Black Box; power tubes are switched from KT150 to KT120 / PranaFidelity Dhyana speakers, dual JL Audio Fathom 112 v2 subwoofers/ analog signal cables: ZenWave Audio D4 interconnects, ZenWave SSR-11 speaker cables / Solid Steel HW-2L component rack and HRS platforms for preamp and amp

Power: Dedicated 10 AWG shielded line (MC 10/2) from breaker box to Furutech GTX-D NCF(R) outlet, 9 AWG ZenWave Clear Bass cable to Furutech e-TP609 NCF 6-way power distributor / ZenWave PL-11 power cables for DAC, preamp and amp / ZenWave Clear Bass power cables for CD transport, 10 MHz clock, subwoofers

Acoustic treatment: IsoThermal TubeTraps, TubeTraps, Tri-panels, SoundPlanks, WindowPlugs, ceiling diffusers (all ASC), ceiling cloths, polypropylene basketweave carpet in listening seat area, wooden floor diffusers

Room dimensions: 24 ft long x 12 ft wide (13.5 ft at small window bay) x 8.5 ft high
 
Yet the combo of CDT3 with external Mutec REF10 SE120 10 MHz clock is the icing on the cake. After hearing the meaningful differences that it brings to the music, I cannot imagine my system anymore without the Mutec clock in it.

I received my unit, and the Mutec cables for it, from Alex Crespi at UpTone Audio who recently became a Mutec dealer. The service that Alex provides is impeccable and he was very helpful with answering all my technical questions in depth and great detail. Few dealers will have such technical expertise and will engage with the customer as much as he does.
Hi Al:
So glad that you are enjoying the fabulous REF10 SE120 in your already terrific music system! I also enjoyed reading about your musical selections and may need to pick up a couple of those recordings for myself.

UpTone has been proud to represent Mutec--for the past 18 months--and we find synergy with both our EtherREGEN and a lot of clients' systems. Plus the excellent value Mutec REF10 Nano (which we keep in stock at all times) also accepts an external DC power supply and since we began production and shipments of our new JS-4 LPS this month about 15 REF10 Nano owners have ordered their supply with the SpeakON>Mutec connectors on our SAPPHIRE cables. A fine match.

Thanks and regards,
--Alex C.
 
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Thank you, Al, for this very comprehensive and beautifully written review!
 

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