Article "DSD vs. PCM: Myth vs. Truth"

[james]

https://www.mojo-audio.com/blog/dsd-vs ... truth/

Interesting article. [Of course it's by a company trying to sell a DAC but it still has a lot of useful information]

Here is the main website of the company ..

https://www.mojo-audio.com/

[Claus]

Thanks for the link! Intresting article.
Even more interesting to see the inside of their crazy priced DACs! Looks like 1000 euro worth of components at best... Unless there is something I am missing...

[Fran]

Interesting alright,

Some of you here know that a group of us diyers have been working on a DAC here - its based on the same (now obsolete but still available) chip from Analog Devices - the AD1862. This was a class leader in its day )I think the audionote DACs used it, and later when it was phased out, its first cousin the AD1865), one of the last ladder DACs before delta sigma became the norm. The AD1862 is only capable of 20bit....

I can tell you that the AD1862 DACs we built sound fantastic, and I think for most of us it is a real reference, and possibly the best we have heard - including all the stuff in Munich. The output stage following the DAC has a large influence on the sound, and most of us have settled on a valve based stage here, but not exclusively. From the picture, it looks like they have used a discrete solid state output stage here and no doubt they have implemented it very well. We don't get to see what the USB to i2s converter is from their pics.

[hudo]

The AD1862 is only capable of 20bit....

Best sigma delta DACs can actually barely do 20-21 bit of real resolution and dynamic range, despite being "32 bit" :) Usually its well below 20 bit, around 16-17 bit. https://www.maximintegrated.com/en/desi ... rsion.html

As you go more high-end, most DACs are either R2R, or custom sigma delta implementations (not AKM/ESS).

Like that article explained, there's something special with R2R. I went that road also, first with Schiit (AD IC), then Holo (resistor ladder) true NOS, with computer based upsampling with HqPlayer. Quite pleased with the results, no upgrade-nervosa any more, i just tweak upsampling algo from time to time (Hqplayer has bunch of them).

[james]

Interesting that the DAC site claims that vinyl cylinders would have been better than vinyl discs. Probably true but not that practical considering the amount of apace they would have taken up.

I remember the tir-na-hifi DAC build. I did not even try to get involved since it is a long time since I soldered anything (and even longer since I learnt any electronics, as part of physics).

The idea that anything above 20-bits is inaudible is interesting. I suspect 24-bits is just used because (like 16-bits) it's a multiple of 8.

[hudo]

The idea that anything above 20-bits is inaudible is interesting. I suspect 24-bits is just used because (like 16-bits) it's a multiple of 8.

20bit requires ~120db of dynamic range. What DAC can go that level? :)

Thats why Schiit is joking with the latest Bifrost 2 64, that it has 64bit resolution (and actually is around 16-17bit). The fact that signal is processed 24 or 32bit internally (internal DSP/upsampler), it doesn't matter much at the end.

[Fran]

I would put at about 800-900e parts in there if you were building eg 10 of them, including the chassis. Of course there are setup costs as well, we have to understand that. They use the JLsounds usb board (which is good, from memory <100e) and I cannot imagine they use anything other than a WM8804 chip for SPDIF. The other digital circuitry to split the data into left and right is not shown either.

Chassis looks like an off the shelf extrusion with custom front and back plates. Add what is probably two largish PCBs, molex power connectors, that EMI filter, IEC socket and hardware, that might add up to 150e.

AD1862 chips have a minimum order now through digikey - I think minimum order is 14 of them which works out around 300e ballpark. I know we paid about 60usd a pair for the ones we used. Custom transformer is around 60-80e max. Lundahl chokes are 120e each - again this is retail price.

Anyway, I wish them luck with it, and to any owner as well. The AD1862 sounds excellent, if they have a really good class A output stage, with good power supplies that will work really well. The JLsounds board is a good solution too. It adds up to a 2k DAC though, not a 15k one.