I would say 95% of my customers who had the PecanPi and PecanPi+, prefer the plus(+) version. The two comments I get most often comparing the two is that the plus(+) version sounds more natural and has a much better soundstage.
Okay. That's great.
However, I would suggest to look into the noise problems with RPi GPIO bus, not to mention the jitter.
Understood you probably have a customer base looking for something low-ish cost and yet a little bit out of the norm (which is mostly dominated by Topping, SMSL, etc.).
That said, I am a SQ perfectionist oriented guy. When I can hear a problem I will say so. And I have said so about commercial dacs before. I do it because I want people in the forum to know what they would be getting relative the big picture of what is possible with the best of dacs or pretty near to the best (which could be at any price point).
Most likely if I heard one of your dacs I would write about whatever I found imperfect about it. Pretty sure there would be a fair amount. But, I haven't heard one so for now I have no exact opinion.
In the meantime, don't know if you have been following the discussion in @MarcelvdG RTZ FIRDAC thread. In not, you might find it very interesting although maybe a bit technically detailed in places. Important stuff, IMHO, going forward for a designer of dac products. https://www.diyaudio.com/community/...-register-firdac.379406/page-154#post-7679014
If it helps to get up to speed, feel free to PM. Happy to discuss issues affecting dac design.
However, I would suggest to look into the noise problems with RPi GPIO bus, not to mention the jitter.
Understood you probably have a customer base looking for something low-ish cost and yet a little bit out of the norm (which is mostly dominated by Topping, SMSL, etc.).
That said, I am a SQ perfectionist oriented guy. When I can hear a problem I will say so. And I have said so about commercial dacs before. I do it because I want people in the forum to know what they would be getting relative the big picture of what is possible with the best of dacs or pretty near to the best (which could be at any price point).
Most likely if I heard one of your dacs I would write about whatever I found imperfect about it. Pretty sure there would be a fair amount. But, I haven't heard one so for now I have no exact opinion.
In the meantime, don't know if you have been following the discussion in @MarcelvdG RTZ FIRDAC thread. In not, you might find it very interesting although maybe a bit technically detailed in places. Important stuff, IMHO, going forward for a designer of dac products. https://www.diyaudio.com/community/...-register-firdac.379406/page-154#post-7679014
If it helps to get up to speed, feel free to PM. Happy to discuss issues affecting dac design.
I am well aware of these, for jitter my DAC has a full reclocking circuit that takes care of this with a Crystek clock source. You can see that in this test result here.
As for the noise that is significantly reduced by turning off the Rpi's wifi and Bluetooth.
Hence on my streamer(s), the only option is ethernet. The DAC has an SNR of 133dB, so there are no noise issues.
For those that dislike the Rpi, the DAC also has a SPDIF input so it can operate without an Rpi.
@orchardaudio I don't believe your claimed measurements are reliable indicators of SQ. Don't even know if they are from your dac. How about lets see pics of your test setup, and your measurement equipment. Let's see how you have it all setup including the wiring and the test equipment settings. Let's see how much you know about how to measure your dac. You know how to measure deterministic jitter? How to visualize noise skirts? Let's also see if you know how to power a Crystek clock, how to get the best sound out of one? How many Crystek clocks of what model do you use and at what frequencies? Is your dac RPi GPIO bus I2S clock master?
Better yet, just send one here for a listening test by some professional high end audio designers. You will get honest feedback. Because if its as good as you seem to be claiming, then I'm sure everyone will be duly impressed. It would be the first time people would be impressed with a simple RPi hat dac, but maybe it could happen if the SQ is there. We can take price into consideration too. Not fair to compare it dacs in a different price class.
Better yet, just send one here for a listening test by some professional high end audio designers. You will get honest feedback. Because if its as good as you seem to be claiming, then I'm sure everyone will be duly impressed. It would be the first time people would be impressed with a simple RPi hat dac, but maybe it could happen if the SQ is there. We can take price into consideration too. Not fair to compare it dacs in a different price class.
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IME there will be noise and historically its easy to demonstrate with hat dacs. Any owner of one of those boards can do it and see for themselves.
Okay. So how is SPDIF clock recovery accomplished, with a PLL? Or is there an ASRC? If so what are the specs on the ASRC? Also, how is the board powered?
Just out of curiosity - did you turn of the RF aggressors because they affected the measurements?
Thank you for your interest in our test procedures. While we strive for transparency, I must address that your approach appears to contain unfounded accusations and lacks respect for my expertise. As such, I find it best to not engage further in this discussion. I stand by the integrity of the measurements and the thoroughness of our testing methodologies. Should you have genuine inquiries or seek constructive dialogue, I remain open to discussing those matters. However, it's imperative that our interactions maintain a professional and respectful tone. Thank you for your understanding.
A lot of implementation information is here:
https://orchardaudio.com/pecanpi_plus_implementation_spec_test_results/
Sorry for my tone yesterday. I agree it was a bit excessive. However, it arose from looking at measurements that look almost too good to be true for an RPi hat dac. That said, a few people have been quite good at achieving very good standard measurement results using fairly simple circuitry (say, for example, Cosmos). Unfortunately in those cases where measurements impress, particularly in the case of complex devices such as sigma delta dacs, often there is limited correlation between standard measurements and perceived sound quality. IOW, it is as through the equipment was designed to satisfy the eye looking at graphs more than to satisfy the ear listening to music. Moreover the point not that people like distortion, its more that not all forms of distortion and noise show up well in standard FFT measurements. In addition, ESS pointed out some of the issues in a presentation given several years ago. Would you in general agree with the foregoing observations?
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At $500 the PecanPi+ DAC which is 10x the cost of a "typical" Rpi DAC, I don't think it should be looked at the same way.
I partially agree with what you are saying. Some measurements do not directly correlate to sound quality especially something like THD+N at a single frequency like 1kHz.
Many of my customers run my DAC through a tube pre-amp (or use one in front of my amplifiers) which adds all sorts of distortion and other effects, which would make the measurements much worse, yet they like the sound.
However, the premise of my company is that good objective results will yield good subjective results. My R&D efforts are focused on finding a correlation between objective and subjective.
I believe I have been quite successful at this if you take a look at all of the awards I have received from subjective publications and customer reviews.
I partially agree with what you are saying. Some measurements do not directly correlate to sound quality especially something like THD+N at a single frequency like 1kHz.
Many of my customers run my DAC through a tube pre-amp (or use one in front of my amplifiers) which adds all sorts of distortion and other effects, which would make the measurements much worse, yet they like the sound.
However, the premise of my company is that good objective results will yield good subjective results. My R&D efforts are focused on finding a correlation between objective and subjective.
I believe I have been quite successful at this if you take a look at all of the awards I have received from subjective publications and customer reviews.
Regarding a measurement that may help find correlation between objective and subjective, do you have any thoughts about the measurement technique described and discussed in the thread at:
https://www.diyaudio.com/community/threads/phase-noise-in-ds-dacs.387862/post-7063038
https://www.diyaudio.com/community/threads/phase-noise-in-ds-dacs.387862/post-7063038
Albeit being old this is a good paper on the topic.
https://www.aes.org/e-lib/browse.cfm?elib=8354
Jitter was heard at much lower levels when playing pure tones, with actual music there had to be a lot more jitter present to hear a difference because music obscures it.
Regarding your direct question, I have not done any specific testing on how the skirts affect audibility, so I cannot comment on that.
https://www.aes.org/e-lib/browse.cfm?elib=8354
Jitter was heard at much lower levels when playing pure tones, with actual music there had to be a lot more jitter present to hear a difference because music obscures it.
Regarding your direct question, I have not done any specific testing on how the skirts affect audibility, so I cannot comment on that.
IME jitter is often misunderstood by engineers relying on old published research. Also IME, audiophiles weren't always imagining things that aren't real. That sort of explanation is a common reaction by engineers who are using oversimplified models of the system they have designed, and or who are misinterpreting published research (such as the common misunderstanding regarding thresholds of audibility). Also, the denial effect in engineers is not limited to audiophiles. I have seen the same skepticism and denial from engineers designing complex medical devices which, if faulty, can pose severe life-threating risks to patients. Too often engineers assumed trained medical professionals were imagining things that couldn't be true because, "the machine can't do that; that's not how it works."
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