Model S4 is coming

As I wrote in the October 2011 series of TDA1541A articles, back at that time, when I designed Model S USB, I did not plan to design new DACs with TDA1541A anymore, nor to redesign existing ones in any significant way. AYA DACs were already discontinued, and my plan was, once the TDA1541A Taiwan series I was using is spent, to move the other ways. And there were no major changes in the Audial Model DACs design since those days: only some passive parts were replaced, and PCM/I2S direct input was added to the Model S Mk3. Similar small changes were done with late AYA II limited DIY runs.

Now, being faced with depleted TDA1541A Taiwan stock, things look a bit different. It is definitely the best TDA1541A series so far, and I don’t have to add anything here. However, some other series are still available, with the performance that is not up to Taiwan production run, but the differences are not that important, to justify dropping such a great DAC designs completely at this moment. That is the first thing.

The second is, back at the same time when I’ve been designing Model S USB, one of my goals was to prove TDA1541A not sounding murky. So the Model S USB was tuned to sound open, with maximum resolution and definition. However, the feedback I had from some Model S USB customers was that, even if it is the highest resolution DAC they’ve ever had or heard, with a generally natural tone, it can get a bit too open with some recordings. A comment I’ve never received about S/PDIF Model S, or AYA II DACs.

In the meantime, after the Model S USB release, I kept working on USB stage. As good as it originally was, it took me some years to tweak its details. Now, in its current shape, this USB front end can play everything original Model S USB front end could play, and even more than that – and it can play it all in a very calm manner, easily, with improved transparency and sound stage positioning.

Obviously, it is a chance to apply these later USB stage developments in the Model S (USB) too. In addition, such a USB / TDA1541(A) setup now can be made to work up to 384 kHz.

The third thing is, with this revision, we are making a major step to surface mount parts. Audio critical passive parts not available in SMT will be excepted – so no compromises here. Mind you, SMT does not only facilitate production, it also makes some further layout improvements possible.

Speaking about parts, the good news is, the analog supplies will use Rubycon ZA for local bypasses – my favorite Rubycons that were sadly discontinued several years ago – I came across some stock, that will last for some time.

So, Model S4 is coming, and it will be released this May. It will have USB and S/PDIF input and, with the above described changes, the rest of topology you know from previous Model S DACs.

Model S USB will be discontinued, whereas Model S Mk3 will remain available, for the time being.

7 thoughts on “Model S4 is coming”

  1. Chad scriven

    Hello. Just so I’m clear.
    1. The new S4 will be using the tea1541 dac.
    2. The S4 will have spdif and usb inputs.
    3. What sampling frequency will both spdif and usb support.
    4. What is the cost in US dollars for the base model.

  2. Hello Chad,

    Yes, S4 is TDA1541A based DAC, with S/PDIF and USB input.

    At S/PDIF input, max sampling frequency is 96 kHz.

    At USB, S4 with master clocks 11.2896 / 12.288 MHz supports sampling frequencies up to 192 kHz. With master clocks 22.5792 / 24.576 MHz it supports sampling frequencies up to 384 kHz.

    Some people, including myself, prefer to use the lowest possible master clock frequencies. In that way, if you don’t plan to go beyond 192 kHz ever, then I’d suggest the first option. If you however plan to listen to the 352.8 kHz and 384 kHz, then it is the second. The best sound I’ve ever heard came from 352.8 / 384 kHz recordings, but the problem here is that there is not a lot of such recordings around.

    If you choose to pay by credit card / PayPal, it will automatically convert the currency. For payment by bank transfer, the price for the unit with classic capacitively coupled output, which applies until 31 May, is US$ 2150.


  3. Hi,i have model s dac and love it,one of the most musically satisfying dacs and i have had many.It is currently being used with 120v ac,however i am moving to Cambodia and the voltage is 225v in the house. My friend (sonic frontiers/parts connection engineer)had a look inside and it appears it can be reconfigured for 230v operation from his observation.Can you confirm this and any instructions/guidance ? I notice it has 2 power transformers,is 1 an isolation transformer ? Lastly, i would like to stream from tidal,what can i do to update this unit to usb input? Thanks

  4. Hello Mark,

    Yes, the first transformer after the mains switch is the isolation transformer. The isolation transformers in these units are usually made with double primary, wired in parallel to operate at 110-12 VAC, and in series to operate at 220-240 VAC, So, generally the 110-120 VAC unit could be reconfigured to operate at 220-240 VAC (and vice versa). Please let me know if you need more details.

    Another option is to use step down mains transformer. This is probably the easier way, and there is no need to be reluctant about it, since such a transformer will act as another mains filtering stage.

    Regarding the USB, unless it is the Mk3 version, it will be more practical to look at the options to equip PC with quality S/PDIF output. With Mk3 there is a bit more choice since it can be also used with I2S (or simultaneous data) sources. Otherwise, in order to literally add an USB input, you should be prepared for more substantial rework.


  5. Mark Schrauwen

    Thanks Pedja,i have the S2 dac.I read your assertion about bnc connections.I have had conversations in past with Ron Bauman of Omega Mikro/Insound regarding some engineers obsession with text book 75 ohm bnc spdif connectors.He is one of the most brilliant and experienced rf engineers in the world.After being employed by the USN and pentagon to work on satellites etc, he now designs and builds arguably the most musically revealing cables,digital front ends,ss v-fet se amps and modified reference gallo speakers.Some of the most real sounding music reproduction i have ever heard.His opinion,based on listening tests is that it is NOT significant to audible performance,that other aspects of connections/cables are far more a priority.I will be installing 1 of his custom rca jacks in place of 1 of the bnc,then test by listening direct with rca and alternate to bnc with adapter.Later i will probably bypass the input switch(or relay probably?) and wire internally with omega mikro copper ribbon.Love the music from your dac,great work.

  6. Mark Schrauwen

    I have a huge inventory of very high quality film foil caps;pp,ps,teflon/silver(that i formerly distributed to several other mfgers).Also a moderate inventory of black gate caps.In the past i have primarily produced tube amplifiers and upgrades to Audio Aero cd players/dacs( blue moon award for SE upgrade).Coupling caps i have found can be a huge upgrade in tube circuits. In fact, i think they are the highest value improvement.I respect your thorough development of this excellent s2 dac(mine is transformer coupled).What locations in this dac might be served with higher quality caps,if any? Can you provide a schematic so i and my associate Glenn Dolick of Parts Connexion/former SF engineer can better explore upgrade possibilities ?Thanks

  7. Hello Mark,

    I am sorry but I can not provide a schematic circuit in this case.

    You will be however easily able to experiment with different coupling capacitors. The PCB points marked “L Our (DC)” and “R Out (DC)” should be used to connect the output coupling caps.

    My experience with the S/PDIF line is different: bringing the impedance in order brings the sonic benefits too. The impedance is however by no means a whole story about the cables and connectors, or about the source output driver and receiver input circuit for that matter.

    Yes, the input switch is the relay. Please let me know in case you need detailed information on how to bypass this one.


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