"I'll soon write out its design brief. I still have to build up the full prototype so all manner of small changes could influence certain details of your text." I reminded Cees that being online not in print meant that real-time edits were child's play. We'll follow this story through whatever little twists and turns it might take. That's always more fun than any narrative straight as a canal. Living things meander. Even our systems are in a constant state of flux.
Soundaware D300Ref ⇒ Denafrips Terminator ⇒ icOn 4Pro SE ⇒ Kinki Studio EX-B7 ⇒ sound|kaos Vox 3awf ⇒ Zu Submission sub ⇐ HifiStay rack and footers.
Cees'd operations. Leonid Burchev of then WaLab contacted me many moons ago to review his new DreamDAC for which he claimed revolutionary tech. After reading up on it, I couldn't help but point out that for already years our flying Dutchman had done discrete R2R with split digital signal to process the lower bits separately and at higher resolution before summing two analog streams with gain correction; and implemented volume control with variable reference voltage to avoid bit-stripping digital attenuation and trimming fixed gain by analog pot. As it turned out, all of Leonid's presumed original inventions overlapped prior art. I can't know for sure but there's a good chance this revelation might have played part in that particular project's ceased operations. That isn't Schadenfreude, just sober reminder that anyone who claims a world's first anything best be sure in triplicate. How one ever could be so sure I just don't know*. Rather than claim that Sonnet DACs are the first or only ones to do it, we simply say that if you want a discrete ladder DAC with truly lossless volume, those from Cees tick all your boxes. Doing so has been his core credo since the early Metrum Acoustics days. In the analog domain, Bakoon Int. use a variable resistor at the output of a proprietary discrete current op-amp to set their amplifier's gain factor. The upshot is the same. Like Metrum/Sonnet digital, the signal-to-noise ratio remains constant regardless of output level. With standard digital attenuation, one drops one bit of word length per 6dB of signal cut. Trimming fixed gain in the analog domain has noise increase as signal decreases. That compromises S/NR at low playback volumes so is lossy as well. Variable amplification factor like Ayre do it too is the solution.
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* A patent search is far from conclusive when many inventors opt against a patent because it would force them to publicize their invention in great detail. It's why Soo-In Chae of Bakoon relinquished his patent application for the Jet-Satri bias circuit. "The patent examiner wanted far too many details. Why spell them out only to give our competition a clear road map to copy us?"
"The success of Morpheus was its performance versus cost. Having all production processes under one roof does reduce build costs rather a lot. As mentioned in your Morpheus review, power handling is very important. Wherever power draw can be reduced, there's an automatic reduction in radiation and noise. Still we have customers waiting on heavy aluminum chassis with big transformers and separate boards for digital and analog. We can and will create such designs in the future but Morpheus already proved to us how successful smart design and reduced power draw can be. We know exactly how Morpheus surpassed our best older Metrum designs. This wasn't just due to its new R2R modules but how we handled power across the board, especially the ground plane. Below you see the new board as it currently stands. You see eight slots for the vertical DAC modules, one for DSP like our MQA option, one for the digital front end. Thankfully we didn't integrate the latter with the motherboard or the AKM fire would have scrapped the entire PCB. Now I must only redesign one plug-in board. Another improvement is that both I²S and USB inputs are available simultaneously now.
Top layer | ground splitting
"The motherboard uses 4 layers. The top layer is a mix of power, ground, digital and analog signal. In all instances their parts connect to the lower layers like grounds to the first inner layer, signals to the second and power to the bottom layer. As we look to the specs of Morpheus, its performance in many ways exceeds my earlier designs with now a noise floor of ~155dB, channel separation over the entire spectrum of 120dB and dynamic range of 125dB. Again that's not just because of the new R2R modules. The new board layout contributed a lot. That's so despite the fact that all digital/analog activity shares one PCB. With correct layout such specs become possible. Let's take a look at the inner ground layer with all the grounds in use. With Morpheus the brown, green and light blue area connect at a dedicated star point. These areas are quite massive but the brown part for the digital processes is extra large since it will use more layers when available. The green part is the power supply's ground while the light blue zone is the analog ground for the eight DAC modules traveling to the outputs. The purple zone is galvanically isolated for AES/EBU and S/PDIF. The same holds for the deep blue zone which is a galvanically isolated ground for the USB module. We handle the I²S input on another layer."
