Trinity DAC

Elberoth said:

The word 'vintage' is a relative term. The PCM1704 is still in production. They have been eclipsed specs wise by the PCM1792 DACs, but many manufacturers still prefer it to the newer, low bit DACs and continuue to use them. Not many people realise, that even the top of the range PCM1792 is already a 10 years old design ...

Such an excellent measured performance from 1704 is possible thanks to the special time-staggered arrangement they are used in. The DACs are not run in parallel, as in most designs (with inputs and outputs interconnected), but run via a special 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 thing in the TRINITY 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.

Since the Trinity DAC still uses the digital filter, the result is an increase in the effective oversampling rate from 8x to 64x (8x in the digital filter, multiplied by eight by the time-staggered DAC technique).

I know of no other DAC that would use 64x oversampling, as that would require and extremely fast DAC, able to run at 2.8224MHz (PCM1704 tops at 768kHz) and massive computing power. Krell, beeing a Krell, once did it in their Reference 64 DAC using some brute force computing with 4 FPGAs and countless EPROMs. They ended up with a DAC that was huge, required equaly huge and heat generating PSU to power all those FPGAs and eventually didn't live up to its promise, mainly due to the limitations of the DACs used (they had to settle on the only DAC of the era that was fast enough to operate at 64x sampling frequency, or 2.8224MHz - Burr-Brown PCM64; it was an 18-bit device that needed manual MSB trimming and had a fairly high level of glitch in its output, which in turn needed an extra de-glitch circuit in the signal path ...)

Wadia used to do something similar to what Trinity is doing in their 27 DAC - they had used 16x oversampling digital filter and four time-staggered DACs in parallel to get to a 64x rate (this is where I'm not sure how Trinity got their patent granted; most likely Wadia's and Trinity's solutions differ slightly).

MSB has 32x digital filter in their latest Platinium IV series of DACs, so does Chord, but that's it.

Such a high oversampling rate allows the Trinity to work without the anlog filter. This is unique among tha DAC designs I'm familiar with. For years the analog reconstruction filter was (and still is) a real headache for any DAC designer, since it always introduces distortions. (The problem is not dissimilar to the passive crossover in the speaker. Many people reported huge gains in transparency by getting rid of a passive crossover and going active. This is also one of the reasons why crossoverless speakers sound so immediate and real.)

But that is not all. For frequencies 176kHz and above, the DAC works not only without the analog filter, but also without the digital one ! It basicly makes it a NOS (non oversampling) DAC, but without all the problems of NOS DACs and their unfiltered outputs !

But it is only one of the many technical features that make the DAC so special. The next one is DAC selection.

Trinity buys the 1704 DACs from Burr-Brown (TI now) in the highest grade available (K), but it is not good enugh for them. They run a further, in house selection to pick up the best of the best. Not many people realise, that the Texas Instruments specifies the 1704 'K' THD as 0,0008% (typical) and 0,0015% (max). That also means, that among the DACs you will find the very few that are 0,0004% THD.

Trinity buys those DACs in spools of 2000pcs, then measure each and every DAC on a special test jig they designed that allows the DACs to be tested without soldering, and hand picks those that exhibit the lowest THD of the lot. So it is like making your own 'Double Crown' DAC selection (in Philips speak), only in house. (The question remains what they do with the remaining DACs; I doubt they throw them away - most likely they return those to the TI or sell them to other manufacturers).

That strict DAC selection is one of the reasons, the Trinity DAC is so expensive. It is also a major bottleneck for their manufacturing capacity. Dietmar told me that they are olny able to manufacture 3-4 DAC per MONTH. So unless they invest heavily into the selection part of their business, those DACs will always be available in a limited supply.

The third technical reason the Trinity is a superior DAC is the attention they paid to the clocking. They use two fully customized, hermetic sealed Voltage Controlled Oven Controlled Xrystal Oscillators (VCOCXO), which deliver the 2 master clocks of 44.1kHz*512= 22.579200.0MHz and 48kHz*512= 24.576000.0MHz. They claim that the accuracy of those clocks is 1000x (!) higher than the clocks used by dCS (1ppb or 0.02Hz).

And even though it is debatable if accuracy of the clock has any relation to sound quality in audio (what is important is clock stability), the phase noise figures must also be extremely low, as they quote 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.

The forth and reason the DAC performs so well is a well implemented the USB input (with galvanic isolation). The USB interface allows the data to be clocked from a local, free running, ultra low phase noise clock and use its full potential. DACs that use outboard clocks arrangement (dCS, Esoteric) still have to send the fragile clock signal through the loom of cables, and then through a PLL loop inside the DAC - each of those steps adding a certain levels of jitter. I'm not even mentioning DACs that cannot sync to the transport and have to rely on a clock signal recovered from the SPDIF signal, as that is way too oldschool to be even discussed in the realm of state of the art DACs...

Trinity Solution is similar to what MSB does (ultra low phase noise in close proximity to the DAC chipsets) and is most correct from the technical point of view. And it shows.

As for the sound ... lets just say for now, that the DAC sounds phenomenal. I haven't heard anything quite like it. It is a game changing product for me. I'm using this DAC via the USB input, mostly with 44.1kHz redbook files played from my computer. I don't have many 176/192 kHz files, so I cannot comment how it works in a true NOS (non-oversampling) mode. Probably even better.

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MylesBAstor said:

Didn't 47 Labs also eschew the use of the analog filter?

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Audiocrack said:

The PC&Drive was designed after I realized that the first clients of the DAC used only the regular digital inputs, since to set-up a dedicated media PC for the best audio playback can be tricky. You know what I mean. J
The device was not scheduled, but of course I wanted that the clients use the outstanding USB interface for the best playback of both CDs and hi-res files to get a picture of the real capability of the DAC.
Seeing the problems I decided to build a matching source for the DAC, which works as a plug-in and play solution, instead to force the power amp.
To play hi-res file you need always a computer based system, since the DVD-Audio drives down sample in the most cases the data stream, which is linked to the common digital output connectors like RCA or Toslink..
I am not a friend of storing my files on a server in the basement, therefore I decided to create a PC with a 4TB HDD and an optical drive. If the 4TB is full I can easily add a RAID system in a matching TRINITY enclosure, that means we also think a little bit in the future, but who has more than 4000CDs (80min CD needs roughly 740MB) to archive.
The PC&DRIVE can be used to play and archive CDs on the HDD. You can play CDs in real time or you can rip a CD and play the ripped part instead of the CD, whereby you have to wait, that at least one title was ripped and then you can listen the CD and the PC makes a copy in the back ground, which is stored on the 4TB HDD, where you can tag it and move it to the correct place in your library.
The operation system is a Windows 7 Professional, which is installed on a separate mSATA (Solid State Disk), so an use the 4TB HDD only for your music and not for any program installation.
To control the PC&DRIVE I recommend the USB3.0 touch screen monitor, which gives you a very handy tool to select the wanted music file. In the near future this monitor will be available as a wireless system, which even increase the comfort to maneuver through your large music library.

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Elberoth said:

I belive they have pioneered the Non-oversampling, digital filter-less DAC Concept by Ryohei Kusunoki. AFAIK those designs still had the analog reconstruction filter at the output.

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Elberoth said:

(...) As for the sound ... lets just say for now, that the DAC sounds phenomenal. I haven't heard anything quite like it. It is a game changing product for me. I'm using this DAC via the USB input, mostly with 44.1kHz redbook files played from my computer. I don't have many 176/192 kHz files, so I cannot comment how it works in a true NOS (non-oversampling) mode. Probably even better.

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asiufy said:

Adam,

Thanks for the very thorough writeup. I wish Dietmar had taken the time to post such remarkably complete information when he was spending some time around WBF...

I know you don't have the MSB transports, but it'd be great if you could arrange for one to show up and test it with the Trinity, as that seems to be the killer combination for those who want to stick with physical media for a while. It'd be killer to pair a UMT+ and this Trinity DAC, no?

Now that transport seems utterly ordinary. Windows? Bah And Dietmar, I do have more than 4000 CDs (more than 9000 actually)...


alexandre

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edorr said:

Nothing wrong with this approach, but how is it any different than a well designed and build music server, like say the music vault. I he charges the same ballpark as such an existing server, that is OK too. However, it appears there is no "secret sauce" here that will elevate performance of the DAC to levels beyond what is achievable with other well executed designs of source components with USB output .....

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microstrip said:

And now the difficult and more subjective one : how would you compare in general terms the best CD recordings sound quality using the Trinity with the best DSD played through the MSB?

And one suggestion - listening to a DSD recording transcoded to PCM using JRivers ...

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asiufy said:

I know you don't have the MSB transport, but it'd be great if you could arrange for one to show up and test it with the Trinity, as that seems to be the killer combination for those who want to stick with physical media for a while. It'd be killer to pair a UMT+ and this Trinity DAC, no?

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Elberoth said:

I belive they have pioneered the Non-oversampling, digital filter-less DAC Concept by Ryohei Kusunoki. AFAIK those designs still had the analog reconstruction filter at the output.

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MylesBAstor said:

Here are two if I'm not mistaken.

http://www.ankaudiokits.com/dac3_1.html

http://www.6moons.com/audioreviews/nixon/tubedac.html

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Elberoth said:

I do not belive this is exactly accurate.

Scott Nixon DAC. Contrary to what the review says, Scott Nixon admits:

I do employ a gentle low-pass filter set at around 65kHz.

Audio Note DAC. In TNT review, you can find the following statement:

With Audio Note the return to non-oversampling ties in with their earlier efforts on transformer-based DAC current-to-voltage conversion: a transformer forms an interesting low-pass filter to be used with a non-filtered DAC.

They have also verified the response of the filter and posted the results (see the review for the full details).

Our amplifiers don't like the spectral images above 20kHz. These can cause nasty intermodulation distortion which folds down into the audible band. Plus, even though you cant hear it, unfiltered spectral images above 20kHz can still fry your tweeter.

Trinity can get away without the analog filter only because they use the time-staggered DAC arrangement, which pushes the spectral images further into the MHz range.

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Elberoth said:

I haven't heard he made any claims about that. I have all reasons to belive the Trinity transport will sound the same as a regular computer via USB. In fact, some extreme PC-builds, running on batteries or the Aurender W-20 (also with bettery power) will still have potential to sound even better.

The transport was only released as a convinience feature for those who do not have the skills or will to play with PC-audio and need sth that will work just like a traditional CD transport - insert CD, press play and music starts playing. No ripping or tagging neccessary.

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acg said:

Hi Elberoth.

The Phasure NOS1 USB dac seems to use much of the same tech as the Trinity. Eight x PCM1704 and completely filterless (analogue or digital) running femto clocks. The Phasure relies on the computer software to upsample to 705 or 768 and to apply a special Arc prediction filter that eliminates pre and post ringing (called impulse response in the Trinity manual) which takes all of this processing out of the dac which improves dac clock behaviour.

When I read the description of the sound of the Trinity dac I thought that it was exactly how most of us Phasure owners would describe the sound of our dac: that it has no sound of its own. I am quite sure that the designer of the Phasure does not pick the cream from his crop of PCM1704s Like for the Trinity) and it's unusual shape and presentation do manage to keep costs down so it is a fraction of the price of the Trinity, but I sure would love to hear them both side by side one day.

A 6moons review of the Phasure NOS1 USB is here.

Merry Christmas,

Anthony

Edit: I just love that these old dac chips when implemented properly can be used to beat more modern sigma-delta chips...and that they really do make DSD redundant.

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acg said:

Hi Elberoth.

The Phasure NOS1 USB dac seems to use much of the same tech as the Trinity. Eight x PCM1704 and completely filterless (analogue or digital) running femto clocks. The Phasure relies on the computer software to upsample to 705 or 768 and to apply a special Arc prediction filter that eliminates pre and post ringing (called impulse response in the Trinity manual) which takes all of this processing out of the dac which improves dac clock behaviour.

When I read the description of the sound of the Trinity dac I thought that it was exactly how most of us Phasure owners would describe the sound of our dac: that it has no sound of its own. I am quite sure that the designer of the Phasure does not pick the cream from his crop of PCM1704s Like for the Trinity) and it's unusual shape and presentation do manage to keep costs down so it is a fraction of the price of the Trinity, but I sure would love to hear them both side by side one day.

A 6moons review of the Phasure NOS1 USB is here.

Merry Christmas,

Anthony

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