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Those who crack open the DACmini with intent to sniff out secrets will undoubtedly identify Analog Device's 1896A ASRC (asynchronous sample rate converter) and Asahi Kasei's AK4396 24/192 multi-chip DAC with onboard 256-step digital attenuator. The AKM chip also appears in Esoteric machines, massively paralleled in APL Hifi NWO modifications thereof and in the Slim Devices Transporter. Digital veteran Mike Moffat picked the newer AKM4399 for the very first DAC of his new company Schiit. So did AURALiC for their ARK MX+. For CEntrance this choice would actually hold real bragging rights. Richard Kulavik of Asahi Kasei Semiconductors explains why.
IL715 digital isolators with Isoloop™ spintronic giant magnetoresistive technology; AKM AK4117 digital receiver; clock

"This DAC is a large departure from other delta-sigma DACs designed by us and others like BurrBrown, Analog Devices and Cirrus Logic. The AK4396 is an entirely new modulator, pioneered and patented by AKM. It achieves something unique. In the past, many of the old Phillips and BurrBrown parts were R-2R based. These were looked upon as some of the best. One of the reasons was high frequency noise. In older R-2R parts, HF noise was not present. In all delta-sigma parts prior to the AK4396, everyone has fought HF noise caused from the delta-sigma modulator with the insertion of large filters and other parts to attempt to solve a problem created by the delta-sigma design. The AK4396 today effectively does not suffer any modulator-induced HF noise and is over 60dB better than the nearest Cirrus and BB devices. All of this HF noise can cause many audible artifacts downstream. That is the 'miracle' we believe is making the difference today. This part gives you the performance and linearity of a delta-sigma device with the noise performance of an R-2R part, something that was never previously available."

Isolated analog i/o ports; switching relays, output op-amps, MAX4820 relay driver | volume control and lateral impact brace
Michael Goodman: "We place our chips in a specially conditioned power environment. This allows us to squeeze more performance from them than typically possible. That's where the pitch-black noise floor and imperceptible jitter/distortion come from. And you're correct, we only use analog domain volume control without the distortion, clicks and pops associated with digital control. We've certainly had a our share of challenges trying to get the zero-crossing switching truly silent. We'd do digital volume in a consumer piece—and have done in many clients' products we designed—but not in an audiophile piece. The DACmini incidentally is quickly becoming a reference device for mastering engineers. A couple of big names will be announced soon. So far we have passionate feedback from Bob Katz (Dizzy Gillespie), Tom Jung (Bob Dylan), Brian Gardner (Madonna), Dave Hampton (Prince) and Frank Serafine (Ravi Shankar) to name just a few." Hey, it ain't bragging if true.
AK4396 DAC and TAS 1020B USB transceiver | SMPS board
Reluctance to divulge silicon has solid reasons of course. Maker X implements chip Z in inferior fashion. This causes the chip a bad rep. Anyone else using it gets blamed for the other guy's design deficiencies. It's how urban myths start. It's déjà vu all over again also for adaptive vs. asynchronous USB. "The USB argument comes down to jitter management. It goes as follows. In synchronous mode the device is the clock master. In adaptive mode the computer is the clock master. Either way works fine if correct design principles are followed. Here is the tricky part that often gets omitted. No matter which side is the source of the clock (PC or DAC), the two devices are still connected by the USB cable. The digital data on that USB cable is always irregular because the computer is involved. Computers do many things at once and end up sending data over USB in irregular intervals no matter who the clock master on the bus is. This irregularity causes jitter. So there is no jitter-free solution just like there is no dust-free house. Irregularity always creeps in. It must be actively managed.


"Here is where the asynchronous vs. adaptive argument breaks down. In either of the two clocking schemes, jitter is present during transmission. It's inevitable and okay if properly cleaned up prior to D/A conversion where it matters most. Neither clocking scheme is superior. Both are capable of performing well if you know how to reassemble the bits prior to the DAC. How do you actually do that? There are many ways. The oldest and simplest is buffering. Irregular data comes in, regular data goes out. The most important part is to make sure that samples leaving the buffer on the way to the DAC are clocked accurately. DACport employs JitterGuard™, a proprietary two-stage clock management system that does just that. It cleans up the jitter on the USB bus so that samples are virtually jitter-free at the D/A conversion point."

Underside, both top and bottom covers removed
   When I first quoted these paragraphs in my Burson DA-160 review, Wavelength's Gordon Rankin took me to task for spreading bad intel. And he and his licensees should feel unhappy by Goodman's contention. It pokes deliberate holes in their carefully cultivated perception advantage of async's superiority. Leaving an informed dispute to the engineers, we might simply ask who CEntrance is. After all, credibility of any claim is directly proportionate to who makes it. Besides working closely with all important semiconductor fabricators as often 3rd-party design firm (Agilent, AKM, Analog Devices, BridgeCo, Cirrus Logic, Crystal, Intel, Motorola, Oxford, Portal Player, Texas Instruments, XMOS, Wavefront, Wolfson), CEntrance also develops drivers.


Their current portfolio contains six proprietary firmware codes for USB interfaces, three for FireWire, one for Ethernet. They also co-develop hardware for Harman, Mackie, Korg, Tascam and Waves. They've consulted for the aforementioned hifi firms and the usual OEM agreements mean that many clients remain hidden behind non-disclosure agreements. CEntrance also maintains close working relations with the software teams at Microsoft and Apple. In short, when certain experts in the music, broadcast and consumer electronics industries need help with stable multi-platform designs, they often turn to CEntrance as the brain power behind their thrones.
The boards attach to neither top nor bottom cover but are suspended solely from extruded trusses on the front and back halves.
Like Bryston, dCS, Esoteric/Teac, Manley Labs, Meitner and Weiss, CEntrance thus has legs in pro and consumer. Where CEntrance differs is behind the scenes. Their own brand is just one aspect of their work. One assumes a highly competitive edge from this unusually direct and comprehensive overview of various market segments, never mind very real in-house expertise to become destination for so many companies in the first place. Relative to the adaptive/asynchronous argument, one must look behind propaganda and counterganda and acknowledge that as usual, implementation is senior to fashion. With CEntrance's code-writing expertise for custom drivers, if asynchronous USB were truly superior per se, wouldn't team Goodman and their many clients have transitioned long ago? Riding rather than bucking fashion trends would surely be far more appealing to their marketing departments too. As is, CEntrance prefers contrarious. That's quite the statement in and of itself.* (On that note, Daniel Weiss' FireWire implementation remains adaptive too.)
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* We've compared async with adaptive and they sound the same. We may offer both implementations in the future so people could compare. But that's not really the point, is it?"
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