As you can see from the previous diagram, jitter tends to change in time, probably due to a shift in the local oscillator frequency connected to temperature drift. In these cases the digital source and the analog analyzer are the same sound card, which should reduce if not completely eliminate the effects of low frequency source jitter.
This is instead what happens driving the DC-1 with an external digital source (Linn Mimik): as you can see, there are a lot of jitter artefacts spread throughout the audio band. I find it difficult to find an answer, only explanation I can imagine is some kind of interaction or beat between the original clock, the reclocking clock and the analyzer clock, perhaps connected with the rather slow transition times shown by the oscillogram of a single sample, full range pulse (see below).
Distortion at 1KHz, around 0.3%, is not very low, but perfectly acceptable. The 2nd harmonic is in evidence and the following decreasing. As said, this is a direct consequence of the very simple A class output stage and a precise design choice. In facts a correctly shaped harmonics decay, transparence and lower price have been considered more important than a lower distortion: a perfectly reasonable and very tubey approach, indeed. The reference has a somewhat more sophisticated output stage.
In any case, compared with the reference, the unit has a very good behaviour at -60dB (below) and even better, with a lower noise floor, at lower levels, which gives a good idea of its capability in treating low level details.
The following oscillogram of a single sample, full range pulse shows that the DAC is inverting. This is not reported on the documentation, and can also have some effects on the DAC sonic character, especially in terms of impact. Moreover, the pulse is rather distorted, which is not normal in pure zero oversampling DACs: in facts it is a direct consequence of the moderate filtering that has been applied to the output.
However, if you compare the DC-1 output with the output of any "traditional" DAC, you see that the DC-1 pulse remembers what it should be better than the OS DAC pulse: the ringing caused by the anti-alias brickwall filters (used to filter out all the lobes above 22.050KHz) appears even before the main pulse, which is for sure not a very "natural" effect.
Only minor problems were identified during the test.
The major practical issue is the fact that this is an inverting unit, and this can have some effect on sound. I would have liked to know in time for having a listening session with the correct phase, but unfortunately it was too late.
I am used to have the left channel connector on the left side of the right channel connector while looking at the front of the unit, while here it is on the other side. Not a real issue, when you understand it, but... if you have no access to the rear of the units in the normal placement, as in my case, then you have to remember.
Another purely philosophical issue I see is that, given the small budget, a large slice of it must have been spent for the box. On one side, this makes me think that there might have been some chance of spending this amount in a better way; on the other, the project philosophy prevents the designer from adding anything to the circuit. So, once the budget (and the sales price) has been defined, and best audio components have been selected, it makes sense to invest all what is still available in the container.
Well, what can I say?
If we just look from a conventional technical standpoint, the unit has an overall heretic attitude and what's worse has a very high jitter, clearly the mark of The Enemy. It was clearly born in audiophile original sin and in audiophile sin will die, and every audiophile who will be contaminated will follow it into Audiophile Hell, where MP3 techno is played all time long 8-(... Better for you never to meet it, or you'll be lost forever, you'll never resist its flattery...
However, we do not listen through an oscilloscope, so we should better just look at the perceivable facts, and the facts are that this is a nice looking unit, with a solid case, an easy, natural, pleasant and never tiring sound with a very good pace and rhythm, and combines these advantages with an open and direct approach, lots of details, a wide and natural if not very deep and precise soundstage, and no perception of any clock jitter at all.
The price tag, less than 500EUR, can only be black magic.
Magicians, oops, units of this level are very hard to meet at these prices, these days, so, if you think it is the case to upgrade your CD player, definitely try to listen to it. Its voice is rather special, but I think many of you will like it.
There will always be time to build up the pyre, afterwords. If you're not bewitched, I mean: DC-1 has really sold its black soul to the Enemy.
First of all we thank Giorgio and TNT for the review. Giorgio has fully understood from the beginning our project and philosophy. Given a limited budget, what's important is the sonic result, not cosmetics: it would just be wasted money
Our approach does not necessarily require special solutions, but the best solution for our target and our budget. This was the genesis of DC-1, which really presents solutions unusual for such a price tag and in some extent potentially heretic. But in the end they are not!
The design of a low cost D/A converter is rather simple, in facts there are many available on the market, and also some with no low price tag! On the contrary, we could say that the market offers a lot of standard players in very attractive enclosures; these objects are, according to our opinion, too often "empty", without ideas and results: "Nothing under the dress", we might say. Well, this is not the case with our products. We work in the opposite way, and disregard any integralistic attitude and barrier to reach what we intend to. In facts, you need an open mind and a clear vision to be able to offer a product that gives better results for a given price level.
When you listen for the first time to this object, as with our other products, you are not surprise by sonic fireworks or special effects; this is due to the fact that it is extremely natural, and this is not immediately perceived. On the contrary, after listening to the music with this DAC for a while, it is very difficult to return to a normal DAC.
Giorgio has correctly analyzed also the low frequency character. The low end seems a little back, first time, but it very rich. It is a precise design choice. The low end of many products on the market, especially loudspeakers, is gummy, slow and monotone. We hate this so unnatural but so attractive bass. The trade-off is this slightly light bass.
We are absolutely sure that jitter is an enemy of good sound. In any case we looked over it and tested asynchronous reclocking, which has added jitter, but a "different" kind of jitter, and the sonic result has confirmed us that this allowed us a huge step forward. Giorgio has well explained this too, and has also added that there are other solutions, but not at this price.
Finally the enclosure. Even though the cost is for me not low at all, it is not such an high percentage of the overall cost. On the contrary, the solutions adopted have radically reduced the cabinet costs, that would have been otherwise not acceptable. This has allowed us to spend part of the budget in areas with an higher sonic impact. Others might have decided to spend more in a more attractive cabinet in spite of sound. The adopted solutions, however, required a lot of design work togather with the supplier.
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© Copyright 2005 Giorgio Pozzoli - www.tnt-audio.com