What did you use for an ADC and what software is this?
Jitter is very good, too. How do you transfer your signal and what clock does the chip use?
Jitter is very good, too. How do you transfer your signal and what clock does the chip use?
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Audio Precision 515 . When tested with better AP we do better 1-2 db. THD+N we get -112 to 112.5
We play 1Khz digital file direct on RPI (i2s to DAC). We bypass the dpll (using 2 oscillators )
We play 1Khz digital file direct on RPI (i2s to DAC). We bypass the dpll (using 2 oscillators )
I am not sure I understand your question. The static polynomial transfer rotates phases only at multiples of 90°. But a real circuit is affected by dynamic distortions which further rotate the distortion phases.
An example: The first chart shows a real measurement of a DAC/ADC loopback. The phases listed in the upper-left table are different from multiples of 90°, especially H2 and H3.
The second chart is a measurement of a digital signal, generated at the same frequency, the same level, with some white noise added to look similar, and with added H2 - H7 harmonics at exactly same level as the real measurement. The harmonics are generated by chebyshev polynomials, resulting in this static transfer polynomial:
Code:
4.47e-05 x^7 + 7.41e-06 x^6 - 5.60e-05 x^5 - 6.13e-06 x^4 + 3.89e-05 x^3 + 3.26e-06 x^2 + 9.99e-01 x - 1.64e-06The chart shows that all H2-H7 phases are almost exactly at multiples of 90°. They must be, because sin^2(x) yields -cos(2x) (H2 at -90°), sin^3(x) yields -sin(3x) (H3 at -180°), etc.
The third screenshot is my distortion-compensation tool introducing the distortions into the stream.
Yesterday I did a measurement of performance of static distortion compensation using a polynomial https://www.diyaudio.com/forums/equ...nsation-measurement-setup-40.html#post6527152 . The charts clearly show how the dynamic distortion grows with growing frequency, gradually reducing the compensation effect of the static polynomial.
I do not understand your question, please can you explain? Thanks.
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There is one thing I don't get...how are the able (d30pro) to use 4 parallel DACs when the output of those DACs are voltage (not current)..
Most likely they use a R on the output before opamps
Most likely they use a R on the output before opamps
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Either that, or via difference amplifiers. The output would be 20 Vpp then, doable with high enough rails I guess. Since the chip basically has single ended outputs, using 4 of them is similar to how you would use dual AK4493 or AK4497. Two seems like more than enough, though.
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Serious question here in an attempt to understand where objective measurement ends and subjective experience begins. If the objective measurements are so good and so linear and distortion is well below hearing, etc., then why buy anything else? Wouldn’t this be a an end game DAC? For all of these DACs that measure this well, some costing a few hundred, while others cost thousands, all measuring near the same, can there really be a subjective difference between them? Is it possible for a DAC to measure really well and sound like crap?
Thanks in advance for any insight you can give me.
Thanks in advance for any insight you can give me.
EDIT *** Oops - I just realized @cdsgames (representing Allo) had already posted some info on the Boss2 - so ignore this.
Allo is now shipping the Boss2, which is based on the CS43198. They say that the drivers are now included in RPI 5.4.77 kernel onward.
They are also selling a complete player and put up the attached AP FFT on their website: BOSS2 Acrylic
This looks pretty good - I may consider an upgrade for a player I built a few years ago: pi based systems - Page 6
Allo is now shipping the Boss2, which is based on the CS43198. They say that the drivers are now included in RPI 5.4.77 kernel onward.
They are also selling a complete player and put up the attached AP FFT on their website: BOSS2 Acrylic
This looks pretty good - I may consider an upgrade for a player I built a few years ago: pi based systems - Page 6
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Some people think so.
Only one way to find out. For me, the answer is yes, there is more to dac reproduction than is typically measured. Maybe not for you.
Probably not like crap, exactly. IME it is possible for a dac to measure really well, but still have audible weaknesses. Others disagree. There is more that could be said, but ultimately its about finding a dac that you are happy with.
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Other than interface requirements, it's the marketing ploy. Yes, some people fall for it.
Of course. Subjective differences are everywhere even between the two of the same DACs.
It's possible depending on the listening method. In subjective listening, anything goes.
Whether or not distortion is well below hearing remains a controversial question. The claim that distortion is below hearing is based on a couple of questionable assumptions.
One assumption is that hearing is always linear or at least it is no more than weakly nonlinear, so reasonably accurate calculations of what what should be inaudible can be made.
The other assumption is that so-called 'limits of audibility' are hard limits or close enough to hard limits so that they can be taken to accurately represent the abilities of all 7+ billion people on earth. In reality a 'limit of audibility' is measured with sine waves. It is an estimate of the average limit of audibility for a population (50% of the population can't hear below that SPL at that frequency). They are not hard limits, and there is disagreement about what actual hard limit numbers might be. Whether or not sine wave measurements apply to music hinges on linearity of hearing being a valid assumption.
There is no 'proof' for either assumption in general. However, I would stipulate there is compelling evidence for some cases that hearing is more or less linear.
However, I don't believe that hearing linear in all cases. There is some anecdotal evidence from unpublished research that hearing can be remarkably sensitive when noise or distortion is correlated with music being listened to. Unfortunately, there are no published studies on that which I am aware of.
As one can see, there is room to argue and disagree. The arguments have been going on for decades, and there is no end in sight.
A personal observation is that what people believe about hearing tends to correlate with personality type, and to correlate with one's own hearing perceptions. (I find the former tendency to be quite interesting from a scientific perspective, but its getting a bit off topic from diy audio.)
I would be in for such a project. I can do the PCB design. I have ~25 years experience with PCB design and have done many challenging designs in the past.