Review of the Premium 10MHz Master Clock Generator: LHY OCK-2
Master clocks has been the heartbeat in the Recordning Studio field for many years now. It was when the Digital technique was intruduced the technicians found that the oscillator quality direct affect the sound result. 75 Ohm impedance was chosen for the BNC (connectors and cables). 75 Ohm impedance is a common choice for impedance for digtal transfer in both the studios and also in the consumer products (SP/DIF). In the studios a need for longer distances of digital transfers between equipment is also done with balance signal of 110 Ohm (AES/EBU with XLR-connectors). A remark. MUTEC has its roots in the recording industry.
In the High End part of the HiFi community the master clocks have had a place for some years now but lately the great benefits of using a good master clock also has hit the HiFi in the less astronomic priced equipments. Ex. Audio-gd, Gustard.. In the consumer market an impedance of 50 Ohm is often used.
Exemples of the "heavier" brands of excellent master clocks are Mutec, Cybershaft, AfterDark and a few proprietary brands that are very expensive but not performs very good compared to the three earlier named here.
LHY OCK-1
For those who not know the LHY OCK-1, I can explain that it is a rather new, rather simple design with all the parts in one compartment. Its power is EMI-filtered, then a "naked" toroid transformer produces the lower voltages for the rectifiers, a couple of filtering capacitors from Nichicon/Wima. The filtered DC then fine regulates through two LT1963A for the OCXO with a spec of -110 dBC/1Hz(!). Three BNC outputs with an impedance of 50 Ohm (one with Square wave and two with Sine wave). All three outputs has their own buffer to minimize interference between them.
I bought this one on Aliexpress with a good discount. The LHY OCK-1 is doing a very nice job and is a baragin as it comes. It gives a very nice sound with a "wealthy bass"
as I wrote in an earlier post. I think a part of its "rich" bass is caused by its naked toroid transformer. It is rather common that You will get an lightly emphased bass with
them.
Transformers
About transformers. Toroids are very effective but has to be oversized to not run too hot/warm because they have a
hard time to get rid of its heat if pressured. C-core and R-cores are a bit less effective but can handle the heat emmission better with their better coupling between "Core to air" (=more exposed core surface to air). E-I core transformers are easy to build but produces an unnessesary big magnetic field around itself. Has to be shielded if used in these small signal applications.
As I wrote I bought the OCK-1 and it exceeded my expectations big time. For its price (USD350 in my case w. good discounts) it is a home run and it is much better than the Oscilloquartz (-90dBc/1Hz) it replaced. I can absolutely recommend the LHY OCK-1! It is almost surrealistic that a <-110dBc/1Hz OCXO is sold for around USD400-450. Gustard sells the C18 for USD1599.
LHY OCK-2
So we are now looking at the LHY OCK-2. Based on the very good experience with the LHY OCK-1 I couldn't resist to order the LHY OCK-2 when it was announced. I got it the 25'th of November and it is running with power on since. The LHY OCK-2 is a completely different animal compared to the OCK-1. The OCK-2 has been refined in every aspect. First the aluminum box itself. It is produced with CNC-milling machines from a solid block. The finnished box has three separated compartments which holds:
1. Power input/fuse, EMI-filter, UK made Talema transformer, two sets of very fast diodes for rectifications, first stage filtering (Capacitors). =>
2. Second stage filtering and voltage regulation with three independent LT3042's with PNP's (PNP transistors are added to rise the current) =>
3. Correct voltage of excellent quality for the OCXO (<-115dBc/Hz). A fine tuning of the output frequency(don't touch!). Six BNC outputs with three with Square wave and the other three with sine wave.
All the six BNC output have dip-switches with choice for 50 and 75 Ohm impedance and also dip switches for a choice to be connected or disconnected to GND (or ISO). In ISO-mode the receiving of time pulse device(s) GND is/are valid. All outputs also have independent buffers also in this OCK-2.
All these efforts added into the OCK-2 makes all the difference. The LHY OCK-2 is sold as a "Premium 10MHz Master Clock Generator" and it is completey true. I had no idea of how a <-115dBC71Hz OCXO could perform. Now I know.
Testing equipment used
I have tested to feed Audio-GD DI20HE (DDC/reclocker) + R7HE Mk2 (R2R dac), Gustard U18 (DDC) + R26 (R2R dac) and finally a Mutec MC3+USB (modded. Switched PSU trashed, now with an Ultra silent linear PSU). The Speaker rig is based on Audio-gd's Master Power amps. (Master 3+ 2 x Master 2's) and the HE1 as preamp. Speakers are Quad ESL-63's with Gradient dipole basses, SW-63's. Cables used are decent priced. A very transparent, high performing and revealing rig.
The OCK-1 give a cosy, warm feeling and I personally think that this sound charactar will make most music lovers happy. It will fill Your listening room/headphones with a pleasant, laid back, detailed sound. A soft yet detailed mid an highs and a warm rich bass as foundation. A very easy to like sound that also is a bit forgiving.
The Mutec REF10 SE120 is an expensive Master clock with all the qualities You could ask for. The sound is calm, the scene is wide, deep and high. Airy with very precise placing of instruments. Microdetails are easy to spot, even the tiniest, weakest sounds as a light cough from someone far back in the audience, or a turning of note page somewhere in the orchestra. The Mutec REF10 SE120 reveals it all. Not forgiving at all on less good recordings, but fabulouse on great ones.
LHY OCK-2
So the LHY OCK-2. -How does it perform?
A fast discovery is how much the quality of the PSU parts is affecting the the sound result. Known from earlier experiencies is that the "PSU is equal important as the OCXO itself". Meaning: You can ruin the performance of a OCXO with a low phase noise with a less ambitious PSU/internal shielding.
I can tell You that the LHY OCK-2 is more close to the Mutec REF10 SE120 than to the "Cool Cat" the LHY OCK-1. The precision in all the PSU stages in the OCK-2 along with its internal shielding is key I think.
The sound given with the LHY OCK-2 is less bassy or "a bit thinner" compared to the OCK-1. This is because of its all through higher precision in the design of the OCK-2 and choice of the higher quality of components combined. The sound is true and the bass isn't absent, it is just very precise. I have tried both GND and ISO and in my context and there is no audible difference in sound, which is of very high quality on both square and sine wave.
Summary.
The LHY OCK-2 is far better/different OCXO than the OCK1. The OCK-2 has a Hi End impact on the sound. It is for us the more demanding music listeners who want to have the full registre precision. The OCK-2 is just irresistable if You are on a clock hunt and this with Hi End-ambitions. I didn't think this performance was possible to get for less than USD3000. And with multiple outputs and the 50/75 Ohm of impedance chioces, it is almost unreal. The price asked for the LHY OCK-2, of USD749, is a bargain. No doubt. The competition is 4 to 6 times higher priced for the same level of performance.This LHY OCK-2 is up on the doorstep to the High End market.
I think that both these LHY OCK-x Master clocks will shake the market with these values of price/performance. They most likely will sell very well. I will keep mine for sure.
Advices.
If You are a critical music listener, (as I am) the LHY OCK-2 is the right/better choice for You.
If You are listening to pop/rock/electronica/background music, games, I think the LHY OCK-1 is the better choice.
I hope You are somewhat helped with this short review
Finally.
I bought my LHY OCK-2 from
https://www.beatechnik.com/ and Alvin gave me a very positive response when I contacted him. I asked for a relevant Phase Noise plot for the LHY OCK-2. I hope it will sent to me in a short while so I can post it here.
Anyway, I ended up ordering the LHY SW-8 switch aswell. I like the build and the OCXO conducting the ethernet traffic to my streamers. Thanks Alvin.
Edit.
I have intentionally not touched the jitter aspect in the review because I don't have the equipment to measure it but a firm and clear texture in the bass registre can usually be explained with a measurement of a lower jitter level. (Jitter is irregularties in the digital domain causing audible distorsion in the analog domain) Maybe we can get a plot or a number also of the jitter level in the OCK-2 from Alvin.
/Jan
