In one of their talks they chatted about listening to audiophiles and making changes to the design. I wonder if this is one of the consequences.
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ESS THD ‘Hump’ Investigation
- Thread starter jackenhack
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In one of their talks they chatted about listening to audiophiles and making changes to the design. I wonder if this is one of the consequences.
OP
- Thread Starter
- #42
As I mentioned in another post, I have a problem with ground loops when connecting the DAC and the audio analyzer to the same computer. So I need to attach the DAC to an external computer (Raspberry Pi.) But I would like to send the output from my audio analyzer, making the measurement much more manageable. It has a function for outputting one channel from the QA-401 as a regular DAC. Is there any way of sending the audio to the Raspberry Pi with Roon? I've been thinking of using AirPlay, but I don't know a way of doing that. Any thoughts? You can probably guess that I'm a Linux/Mac OS guy by now I think?
Edit: The QA-401 software is Windows only...
Edit: The QA-401 software is Windows only...
OP
If you use dietpi on Pi, it has native Roon (RAAT) support so you will see it as an networked device in Roon. Volumio also works but only supports airplay which truncates down to 16 bits.
1 kHz. It is visible with other frequencies too but the shape varies.
OP
- Thread Starter
- #47
Yeah, I have DietPi installed with RAAT and AirPlay, but is there any way of getting the output from my Windows machine streamed via RAAT?
But I think that creating different test files at the required levels and use Roon to playback is the easiest route.
But I think that creating different test files at the required levels and use Roon to playback is the easiest route.
OP
- Thread Starter
- #48
Ok, on to trying to find a signal generator software that works with dB. Any suggestions?
Bamboszek
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http://efu.jp.net/soft/wg/wg.html is amazing little program. Can generate signals real time or save to WAV.
OP
- Thread Starter
- #50
I'm going to try Audacity first, but if that doesn't do the job, I'll try WaveGene. Thanks!
Now for some hacking. Keep your fingers crossed.
I would be very surprised if the problem goes away by changeing these registers. Surely Topping, SMSL etc must have tested this?
Does any dac with the latest ESS PRO chips have this problem, or is it only the mobile chips?
In that case, it could maybe be a deliberate detuning of the mobile chip by ESS to differentiate them. I.e to make the PRO chips sound better than the mobile ones.
Does any dac with the latest ESS PRO chips have this problem, or is it only the mobile chips?
In that case, it could maybe be a deliberate detuning of the mobile chip by ESS to differentiate them. I.e to make the PRO chips sound better than the mobile ones.
Hehehe....didn't happen! But I was still very impressed!
Veri
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18/38 pro chips have it too. Oppo-205 showed it the least, near negligible. They figured it out... but alas they might 'take it to the grave'
I think it has to do with buffer/IV stage though, besides the obvious chip parameters.
18/38 pro chips have it too. Oppo-205 showed it the least, near negligible. They figured it out... but alas they might 'take it to the grave'
I think it has to do with buffer/IV stage though, besides the obvious chip parameters.
With IV stage probably, but with buffer hardly.
I post this in March audio dac1 one thread but belongs here. I ran a level sweep versus THD, i.e. excluding the noise, and the problem appears plainly there:
It is remarkable in how they give up 20 dB of distortion the moment levels get beyond -40 dB. It seems like a design problem but how would a company like ESS let this get out this way???
What I also find interesting is how it rises smoothly from the -40 dBFS to -35 dBFS level then flattens and even dips a bit. ESS said it was a common-mode problem so it's possible they start exceeding their CMRR and/or PSRR around -40 dBFS and after that common-mode is a fixed'ish fraction of the distortion, covering the intrinsic (classical) distortion products and hiding the benefits of their distortion-canceling mechanism. I also wonder if the cancellation scheme introduced higher CM sensitivity... I have in my day invented some pretty cool schemes to fix one problem that created another (or several others, some subtle as all get out).
Since the I/V stages appear to be single-ended followed by a quasi-differential buffer to single-ended, any tiny mismatches in gain and phase can lead to large reduction in common-mode rejection and apparent increases in distortion. >100 dB CMRR is very tough to achieve.
Yes, using Roon. They won't appear as Windows devices otherwise.
The issue is appearing in so many implementations with different approaches with the exception of Benchmark. It has to be a flaw of sorts that Benchmark discovered due to them analyzing it.
Exactly. But the explanation from Benchmark guy doesn't quite explain it as he implied that the hump problem should only be visible in unbalanced variant. or I got him wrong..?
I don't know that John wanted to teach people how to fix the problem.
He may have even misunderstood which issue we are talking about as we thought it was an IMD only issue at the time. Clearly though, John is very good at micro analyzing audio performance and likely enjoys very good support from ESS so has found and fixed this issue. Or avoided it somehow.I think our effort here to keep analyzing it is good in figure out what is going on. We can get help then from our friendly manufacturers and possibly another push to ESS to listen.
I don't know that John wanted to teach people how to fix the problem.
I think our effort here to keep analyzing it is good in figure out what is going on. We can get help then from our friendly manufacturers and possibly another push to ESS to listen.
Sure, we cannot really expect him to share that kind of knowledge publicly and loose his competitive advantage over others.
On the other hand, effort that you guys are putting into this I find very educative, as pretty much everything else on this forum.
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