Well, let's look at the Nadac and compare it to your "commercial build." Shall we?
First the NADAC:
View attachment 8445
Let's start with safety consideration. Right at input we see the proper colored wire (green+yellow) grounding wiring to the chassis.
This is the most important safety consideration. Should hot wire come in contact with the chassis, there must be a stout ground connection as to trip the circuit breaker all the way back in the panel. This is so important that measurement and compliance with the spec is required in both UL and CE. You want to play fast and loose with our customer's lives, and buy yourself a heap of liability, leave this out with the mistaken idea that this has anything to do with audio fidelity.
Yes there is a mains filter. It is right at the inlet of IEC which means no extra mains wiring running around. That is there because this box has a pretty fancy digital subsystem on the right which generates a lot of noise of its own outside of what the DAC will do (board on the right).
Related to above, the box has both CE and FCC regulatory certification. That means they measured it and installed the right mains input filtering as needed to pass emissions standards. It is no hack stuffed in there thinking it will give you "blacker backgrounds, removing veils, etc."
The DAC and output buffer boards are together with proper layout putting the dac away from the analog output. The balanced connectors are all PCB mounted with no hand wiring. There are no cards on top of cards with connectors which can get loose, get dirty, etc.
Negatives are lack of retainers for the cabling. They are all dangling loose. Like to see these tied to the chassis.
Now let's compare this to Mike's "commercial build:"
View attachment 8446
Right away we see the
most important sin: no ground lug from the AC mains! The wires from the AC mains travel through the case and heaven knows where they get grounded if ever, and at how low of an impedance. On this basis alone, this build gets an "F" for design and safety.
As we know, there is no FCC or CE certification to catch any flaws in this design and as such, it is illegal to import into EU or US.
The enclosure is too small relative to Nadac. Notice how mains components are stuffed so near sensitive analog electronics. Ditto for switchmode power supply. See how far apart it is in Nadac versus here. The enclosure looks big due to lack of scale but in reality it is a mini-component box.
Then there is that useless soft-start whose functionality is in the switchmode power supply and it is only needed for linear supplies with large transformers. Insertion of that requires more mains wiring both leading to it and leaving it.
The switchmode power supply is put in backward. It's mains input needs to face the input IEC connector as to shorten that distance. Instead it is turned 180 degrees requiring again, for mains wiring to run everywhere.
Due to inexperience, the regulators are mounted in a line by the bottom heatsink. These don't dissipate much power. They should have their own small heatsinks allowing optimal layout which is NOT lining them up like soldiers and lengthening their path to their load. Bulk capacitor on the output is also misplaced as that needs to be on the load boards, not regulator.
I could go on but here is the net of it:
any professional engineering looking at Mike's DAC would instantly say it screams hobbyist, kit assembly. That is what it is.
The NADAC DAC on the other hand, says "designed by professionals." Yes, it also screams "low volume" with handwiring that is there. But otherwise, you can't criticise it much by just looking at it.
And you can be comfortable from safety point of view knowing that it has passed regulatory testing.
And we all know this conclusion is true. Mike is not an electrical engineer. Never worked as an electrical engineer. Doesn't understand any of these circuits beyond their superficial block diagram functionality. So he makes mistakes.
Now if he built this for himself, cool. But selling it to others and claiming it safe and CE compliant? Give me a break.
I will summarise:
in my opinion his design is not safe or performant. Until he shows proper independent safety and performance data, that is what it is.
