How much of my design skills makes senseOriginally Posted by ReachtheSky
? I must have many other designers ripping my unit apart just to find out how I do it
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The USB bit is down to thinking out of the box. I use a separate re-clocking for the USB, instead of the same re-clocking of the remaining digital inputs. One reason for that is the fact that for bit accuracy and low jitter purposes a combined re-clocking frequency would be a compromise for either type of signals. So they had to have their own clocks.
The USB circuit is also isolated from the rest of the digital circuit and is in fact on its own PCB that is around 15mm up in the air and away from the main digital PCB. Only two wires go from the USB PCB to the main PCB. That way none of he USB circuitry tracks come in contact or share space with anything else. So digital data from the USB side don't cross path with any other digital signal.
I used the same technique for the output stage. It too is about 25mm up in the air and away from any digital or power supply signal and wiring. All that helps to keep the various signal routes from getting affected by noise and artefacts from adjacent signal routes.
What I found is that even though this method of designing involves the fabrication of several circuit boards, the audible benefits are well worth it. For production reasons, a lot of companies use the far cheaper option of banging everything on one PCB. But my reckoning is that even if it cost me more at the manufacturing end to have four boards when just about everyone else would try to get away with just one, the results from my DAC would encourage more customers to go for my DAC and thereby offset my increased manufacturing cost.
Stan
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. So I trust him when he tells me that he spent months trying out different design ideas and listening to each of them carefully, before settling on the final version.
