Since there seems to be some misunderstanding how the Trinity DAC works, I decided to post some block diagrams I've been creating for the past 2 days (not that it took me that long
).
Here is the first block diagram, which shows how a regular DAC works:
Left to right, we have here:
- an input receiver that gets the SPDIF signal (on RCA, BNC, AES or TosLink) from youtr transport and extracts clock and data signals from it;
- Asynchronous Sample Rate Converter (ASRC) - this is where the upsampling is performed; not all manufacturers use upsampling - some genuinely hate it, which is why I have added that it is an 'option';
- oversampling digital filter;
- then there is the digital to analog converter (DAC) chip itself;
- the current output from the DAC has to be converted to voltage, which is whay we have I/V converter stage just after the DAC;
- after the I/V there is the analog reconstruction filter, which purpose is to filter out all the post converstion 'garbage';
- the last block is the analog output stage that feeds the RCA / XLR outs of the DAC.
The lower row of blocks (red arrows) shows the way the clock signal has to travel. As you can see, is first gets extracted from the SPDIF signal in the input receiver, then goes into the Phase Locked Loop (PLL) which purpose is to synchronise the incoming transport clock with the DAC clock (more on that later).
Now the Trinity is a filterless design, which means that it lacks both the analog and digital filters (at least for sampling rates 176kHz and up). It is not the first filterless DAC - Audio Note, among others, has been making NOS DACs for years. Here is a block diagram for such a DAC:
The greyed out blocks are those that are
missing in Audio Note NOS DAC design. As you can see, there is no upsampling, no oversampling digital filter and no analog filter.
The aim of filters in the DAC is to remove the post converstion garbage and properly reconstruct the analog wave form. The problem with those filters, is they are not transparent. They always introduce some sonic signature - and never for the better. Many people believe, that removig the digital oversampling filter filter and leaving the post conversion garbage does less harm, than introducing the filter. This belief underlies the whole theory behind the NOS DACs - those interested in this topic, can read the original paper on Non-oversampling Digital filter-less DAC Concept written by Ryohei Kusunoki:
http://www.sakurasystems.com/articles/Kusunoki.html
The whole NOS DAC theory was a compromise from the very beginning (both in terms of sonics and measurements - there have been lots of texts written about this, so I will not go into details). Some of the manufacturers accepted this theory, other - rejected it. Dietmar's idea was to keep what makes the NOS DACs great, but find a way to get rid of its problems. In other words - how to have cake, and eat it too. That is how the time staggered DACs solution (LIANOTEC in Trinity speak) was born.
The LIANOTEC gives an equivalent of 8x oversampling rate, without using 8x oversampling digital filter. The DACs are not run in parallel, as in most designs (with inputs and outputs interconnected), but run via a special digital delay line, where each DAC is fed with a slightly delayed signal. This creates additional interpolation points which are situated linearly between the original sampling points.
According to the manual, the whole LIANOTEC DAC behaves like a quadratic series. Therefore, it means that two D/A converters are needed for 2 ? way analog oversampling, 4 for 4 ? way oversampling, 8 for 8 ? way oversampling, etc. The Trinity DAC uses 8 DACs per channel (16 DACs in total), meaning used arrangement gives an effective oversampling rate of 8x.
Below is the Trinity DAC block diagram:
Like the Audio Note NOS DAC I have posted earlier, the Trinity DAC lacks an ASRC, an oversampling digital filter and an analog filter. But unlike the AN DAC, it has no NOS DAC problems, which you can clearly see looking into the perfect measurements of this DAC (it basicly measures like a very good DAC with both digital and analog filter in place, even though it lacks both).
You can also notice, that there are two other parts of the DAC that are missing in the Trinity. First is the analog stage. 16 DACs gives the Trinity enough current, so that the signal coming from the current to voltage converter doesn't have to be amplified any further, but can drive the XLR outputs directly. No analog output stage needed. No analog output stage = less distortions = more sonic transparency.
(Audio Note was not not able to do such a thing in their DAC, as they only use one AD1865 DAC, which doesn't generate enough current. Therefore, they had to use an output stage to amplify the signal. And any gain stage, even some ultra exotic 'Audio Note Level 10, stuffed with silver capacitiors made by british maidens at full moon', will introduce some distortions.)
The whole DAC thing, devoid of analog filter and output stage, looks very, very compact now:
Of course, compact doesn't mean it is cheap to make, as the PCM1704K chips, further hand selected by Trinity inhouse, are
anything but cheap to get (I had written more about this in this post:
http://www.whatsbestforum.com/showthread.php?12023-Trinity-DAC&p=238265&viewfull=1#post238265).
Another thing which makes the Trinity DAC different than a regular DAC with SPDIF input is the USB input and
clocking. As you can see on the graph, the red arrows showing the clock signal direction are now reversed:
This is because the DAC does not have to rely on the jittery clock signal extracted from the SPDIF data stream, but sends its own clock signal to the input receiver. What is more, such an arrangement allows another jitter inducing element - the PLL - to be eliminated, in favour of a highly stable, free running clock, that is supplies the DAC chips directly.
The end result will depend on the quality of the clock used, and this is where the Trinity excells. Trinity most probably uses the clocks with the lowest amount of phase noise (jitter) of any DACs available on the market today. They use two fully customized, hermetic sealed Voltage Controlled Oven Controlled Xrystal Oscillators (VCOCXO) with quoted jitter levels at just 28 fs (that is femtoseconds, or 0,028 picoseconds !) in 10Hz-10kHz range. That is absolute state of the art teritory.
They also claim that the accuracy of those clocks is 1000x (!) higher than the clocks used by dCS (1ppb or 0.02Hz), although it is debatable if accuracy of the clock has any relation to sound quality in audio (what is important is clock stability, i.e. phase noise).
I'm not sure who makes those clocks for Trinity, as they do not have any text on them other than the Trinity logo. I've asked this question to Dietmar via email, but he refused to give out that piece of info. He only told me that they are custom made for him in 22.579200.0MHz and 24.576000.0MHz and therefore the lead time is 12 weeks to get them made.
I've found very similar clocks in one of the the available online catalogs, that look and measure (in terms of physical dimensions) exactly like those used by Trinity, and they cost almost $2000 each in OEM prices. That is the price for a regular 10MHz oscillators, available for next day delivery. Not sure how much more the clcok manufacturer charges for the custom 22 & 24 MHz models in limited quantities ... I can only guess, that may be anything from $3 to $5k
per piece. Since there are two of those in every Trinity DAC, we are talking of $6k-$10k in BOM for those two parts
alone. Now if we consider, that the standard BOM to component retail price ratio in a hi-end (and we are talking here more about a $10k ARC preamp than $200k Audio Note UK exotica) is about 20%, those two parts alone should constitute to $30k-$50k from the $60k DAC retail !
This, with the very costly hand selection proces they run on the DAC chipsets (expensive both because of the number of extra chipsets they have to buy and time needed to measure each chipset) has explained to me, why this DAC costs as much as it does.
And it was me in this thread who have said:
However you look at it - $52,000 price tag is exorbitant. Thankfully, I have added in the next sentence:
If there are other things that make it really special - I would like to know. Maybe the price is not as unreasonable as it seems and the DAC is worth every penny. In which case, there could be at least a dosen of people on this forum interested in this DAC.
I didn't know at the time, that one of those people who would fell in love with this DAC would be
me.
Anyway, back to the main topic. Trinity may be USB optimised, but it also has SPDIF inputs. But if you decide to use one of the Trinity's four SPDIF inputs, it will work just like your regular SPDIF DAC in terms of clocking, with SPDIF input receiver, PLL etc - and the whole advantage will be lost. This is why the Trinity sounds best via the USB input. (This is actually no different to how all DACs with asynchronous USB input work. However the Trinity solution is superior to most, as it uses a galvanic isolation on I2S lines, which prevents the computer noise from entering the DAC - another of many clever solutions employed by Dietmar).
Last but not least. As I mentioned earlier, the Trinity DAC does not use Oversampling Digital Filter only for sampling rates 176kHz and up. It still employs the 8x Oversampling Digital Filter for freq 96k and lower:
Now, before anyone starts feeling disappointed about this, please understad this: problems with Oversampling Digital Filters are two fold. The first problem, is a sonic signature of the filter itself. Every filter has one. None is 100% transparent to the signal. The other problem, people often forget about, are jitter level requirements Oversampling Digital Filter puts on a DAC design. Basicly, if you oversample the signal 8x, the jitter level should drop also by a factor of 8x for the performance not to be compromised. Clearly, this is never the case. If your DAC has say 400ps of jitter, adding the Oversampling Digital Filter will not make it 50ps.
Trinity, has dropped jitter levels to such a vanishingly low levels, that the jitter is no longer a factor limiting the performance of the Oversampling Digital Filter. So even with the filter engaged - and I listen 99% to redbook - the Trinnity DACs sounds utterly transparent to the source.
In any case, you can always use your favourite upsampling software - be it JRivers, Izotope, Sygnalist of Peter's own XXHiEnd - and feed the DAC with the upsampled signal to get rid of the Oversampling Digital Filter for all sampling rates. Pick up your poison
In short:
the Trinity is an ultra simplistic, filterless DAC, made using 16 best, hand selected R2R DACs available and some hyper clocking, which thanks to the innovative time-staggered DACs arrangement, overcomes all problems of the regular NOS DAC designs.
