OP21A-D

This review first appeared in July 2023 on Audiophile Magazine. By request of the manufacturer and permission of the author, it is hereby syndicated from the French original to reach a broader English audience. Ed.

Reviewer: Joël Chevassus
Digital sources: Esoteric K03/N-05XD, Lumin X1/P1, HiFi Rose RS201, Cybershaft OP21A-D, LHY SW-10, Synology DS918 + KenLaudio PSU, Roon Server, Minim Server 2
Preamplifiers: Coincident Speaker Technology Statement Line Stage MK2, SPEC HVC5
Power amplifiers: Red Dragon S500 x 2, SPEC RPA-W3 EX x 2, Coincident Speaker Technology 845 Turbo monaural amps, Kinki Studio M7
Speakers: Vivid Giya Spirit, Leed E2 Glass,Recital Audio Illumine
Cables: Speaker cables from Luna Cables Red, Coincident Speaker Technology Statement MK2, Anticables 3.1, interconnects from Grimm TPM/SQM, CST Statement RCA, Luna Cables Red RCA, ZenWave Audio D4 XLR, DIY
Power cords: as provided by the manufacturer
Room treatments: Microsorber for ceiling, Sofa Akustik for walls
Review component retail price: $6'300 ex VAT, LIPW01 external PSU w. 90cm DC cable $318 ex VAT, semi-rigid BNC cable 50Ω /1m $42 ex VAT, pure silver BNC 75Ω/1m $262 ex VAT

Cybershaft are a fine example of Japanese excellence in electronic design. This niche brand specializes in master clocks. It's an area which for years Esoteric left wide open by only offering a single model and that with an atomic Rubidium clock in their Grandioso line. Think €35'000 so far beyond the reach of mere mortals. Yet their TEAC subsidiary continued to promote machines with 10MHz clock inputs to maintain strong interest in external clocks that might boost their performance. dCS too remain active in the sector, with their lower Lina model priced at €8'750 whilst the very beautiful Vivaldi soars to €23K. So there was room for new players and alternate more attainable options. Antelope remain mostly confined to the pro sector since their very technical devices never really won over the audiophile public. Unlike them, Germany's pro company Mutec managed to straddle that fence. Their OXCO clocks gradually established themselves as references for studio and experienced home users. Other doors opened in Asia where a gradual upmarket move meant numerous oscillator sightings from the likes of Denafrips, LHY and Silent Angel. It's here where Cypershaft fit in as a small Japanese boutique offering one of the best clocks below what the top players charge. Cypershaft situate closer to Mutec. They began with selling a 10MHz atomic master clock for measurement purposes in 2005. That used a rubidium module scavenged from another device to be offered in the most affordable guise possible.

Rubidium at the time was a buzzword and many atomic clocks sold to audiophiles. Cybershaft's rubidium clock had better phase-noise specs than clocks built into CD players and the sonic benefits were readily audible. Yet Cybershaft's Kenji Hasegawa knew that for audio a temperature-controlled crystal oscillator aka OCXO of very low phase noise is more appropriate than rubidium. To obtain a high-precision audio OCXO, he soon began collecting commercial samples from around the globe chasing a specimen with the best measured performance. By 2016 Cybershaft marketed OCXO master clocks that met Ken's stringent specifications. With much experience in calibrating master clocks accumulated since, Cybershaft today grade their models according to laboratory performance. Even Cybershaft's user forum pushed them to constantly evolve measured specs. By 2017 Cybershaft launched the OP21A with a phase noise of -121dB with an offset of 1Hz/ADEV 1.6x13e which then was the best performance in our industry for this type clock. Today its performance seems to have peaked since it's still the firm's top model.

Nonetheless, the first 2017 versions evolved significantly to reach their final form only by 2019. I asked Kenji Hasegawa why Cybershaft hasn't upgraded their range topper since. His answer was clear: "If we were to evolve an OP22A model, its characteristics would demand a phase noise of better than -122dBc/Hz @ 1Hz offset, Allan deviation below 1.3x13e. To achieve this, we'd be down to a very limited supply, probably no more than ten units per year. The impact on manufacturing costs would be significant and more than double the OP21A's current market price. So offering an OP22A would be extremely difficult." Let's then inspect his current best, the OP21A. Cybershaft offer single/multi-output versions, the latter with 4 x 10MHz BNC outputs as shown next. Given the rather small price difference between single and four-outlet models, once we use a separate DAC and transport, the 4-output version beckons already. That's the choice I made. The single-port option seems tailormade for systems with one-box CD players.

Cybershaft's high-end clock comes in very nice casework made from 3M panels magnetically shielded across a broad band plus thermal protection sheets to provide the best possible environment for the oven-controlled crystal oscillator. 50/75Ω can be set via selector adjacent to each BNC. Output ground can connect to the main unit or isolate for each channel. This nets four true configurable ports. The OP21A-D runs exclusively off external DC power whose supply is optional. However, nothing obliges us to acquire Cypershaft's version. Any PSU delivering 13.5V/1A via 4-pin XLR can do the job. The necessary DC cable too is available from the firm. Their ~€300 PSU has twin outputs to power a second device. This linear affair runs off a large R-core transformer made to spec with minimal leakage current and wiring using Oyaide's 102 SSC precision conductor which represents the state of the art in high-speed wide-bandwidth conductor design.