Model S USB, on a more specific level (3)

My previous post sums up the USB front end features, as this is what the Model S USB uses instead of the Model S (S/PDIF) input stage.

And with this difference, the Model S USB is just that, its elder (S/PDIF) brother’s USB complement. So, the Model S USB D/A part, I/V converter, and output buffer are mostly the same.

Overall use of independent supplies for each stage, utilizing multiple common mode RC filtering, followed by quality, low noise, zero feedback, and discrete regulators remain also the mark of this Model DAC.

And again the TDA1541A internal DEM circuit is clocked externally (the world’s unique for Model S DACs), and then the TDA1541A is followed by proprietary zero feedback yet low distortion analog circuits, and highest quality output signal transformers (optionally removed).

The times are however still a changin’, and it is two and a half years since the Model S release, so some parts have been revised. The one change you will find quite visible, and it is about the mains transformers setup. There are still two transformers inside, one of them again being an isolating unit (1:1) that filters the incoming voltage and feeds the main transformer by “balanced power”. (Instead of directing you to buy an additional device for power conditioning, Audial Model DACs are also the world’s unique for embedding isolation transformer inside the actual device.) Transformers themselves are now however EI units, both having external shield, and in addition you will find them placed into separate chamber. This move to EI transformers was done on purpose, and I plan to post a small article once, to point out why.

There are also several more, though to some degree less important updates, but which will remain unrevealed until the official announcement. Some of them will be also fairly obvious from the pictures anyhow.

So, stay tuned! And get ready for introductory offer.

2 thoughts on “Model S USB, on a more specific level (3)”

  1. Care to comment n how the usb version sounds versus the current Model s S/PDIF version? Thanks

  2. Hi Jim,

    Most shortly speaking, the Model S USB is a bit more precise. This is not unusual, as its master clock(s) is (are) locally placed – and this is exactly the advantage I usually experience when using transports directly interfaced to the DACs, as opposed to routing the signal via S/PDIF coding / decoding.

    If I’d have to spot some advantage of (S/PDIF) Model S, it would be somewhat more weight in the bottom end.

    Also, I would have to add that the Model S USB still could go through some changes, though it is also safe to say that it is now fairly close to its final shape. The most important decision still to make is the one about the output stage local decoupling capacitors.

    Yet, these DACs are sonically very similar, and when choosing between these two, I don’t think that the sonic differences are here more significant than practical differences.

    So, S/PDIF is still probably more flexible interface, but for use with PC I’d advice USB version. Also, I don’t know if it counts, but another practical difference is that the S/PDIF version can accept sampling rates up to 96 kHz, whereas now I can report that the USB version is 192 kHz capable.

    Pedja Rogic

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