zenon
Member
Hi!
What exactly You mean?
Place 510p to ground, place 510p to ground adding resistor...
A? B? C?
(schematic is only for illustration)
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ESS THD ‘Hump’ Investigation
- Thread starter jackenhack
- Start date
Hi!
What exactly You mean?
Place 510p to ground, place 510p to ground adding resistor...
A? B? C?
(schematic is only for illustration)
A looks more correct to me. Not 100% sure tho.
I see that Jussi of HQPlayer has shared some measurements.
The IMD hump is reduced when the S2 DAC is fed DSD512.
https://audiophilestyle.com/forums/...easonable-cost/?do=findComment&comment=971583
What this plot shows is that the audible band, below 20kHz is incredibly clean. As so is the ultrasonic band.
There is no spuria above - 140dB in the audible band.
However the DSD 512 in the audible band is worse with clear 8kHz packet noise and 16kHz.
DSD512 is showing no useful benefit. - 120dB or - 140db spuria in the ultrasonic range is neither here nor there. Neither have any audible impact.
It should also be noted that real music never has content at this high level at 19 +20 kHz. - 60dB maybe
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You haven’t commented on the reduced IMD hump and Jussi himself already comments on the USB packet noise (-140dB).
Are you saying IMD hump, with the Pro-Ject S2 DAC, is a non-issue?
I'm failing to see a reduced imd hump in his measurements in that post. All I see is increased spuria in the audible band with dsd512
In the post he says: “You can see the 1 kHz difference product jumps a little at -40 dBFS input level.”
and if you missed it:
“With DSD512 input due to higher data rate you can start seeing the USB packet ticking at 8 and multiples (16 kHz, 32 kHz, etc) at -140 dB level. That packet ticking part is exactly same for768k PCM input, but the IMD hump is back.”
One plot alone isn’t enough to show any kind hump (the topic of this thread) though, is it?
Are you saying IMD hump is a non-issue with this DAC?
I didn't miss anything. What's your point?
I am looking at all the plots in the post you linked to.
What is your interpretation of those plots in the audible band below 20kHz?
In reply to your comment “I'm failing to see a reduced imd hump in his measurements in that post.”
“I'm failing to see a reduced imd hump in his measurements in that post.”
In the post he says: “You can see the 1 kHz difference product jumps a little at -40 dBFS input level.”
There is an utterly miniscule difference in the 1kHz product. - 138 v - 142dB perhaps. Both those levels are utterly, utterly inaudible.
So this IMD hump thing is a non-issue?
The hump is at inaudible levels? With this DAC anyway?
No, what I am saying is that this particular data doesn't really show us what you think it's showing.
However it does raise a question about where the IMD products are appearing. For these measurements of the S2 DAC It shows that the increase in IMD is in the ultrasonic region. This will be inaudible. Its at such a low level that this spuria won't create any further IMD in the audible band.
Hence my question to @amirm regarding the bandwidth he measures the hump over.
It's interesting that whilst we have observed the hump in measurements I have yet to see any credible observations/evidence that it's having a negative audible impact.
Also the S2 DAC may well have good suppression of the hump problem. I would have to check.
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My reply to amir linked back to his measurement which showed a hump
https://www.audiosciencereview.com/forum/index.php?threads/ess-thd-‘hump’-investigation.5752/post-195915
Small hump, not the biggest I’ve seen in amir’s measurements
Seems no one realized this.... It's not smpte imd......Try 60hz + 1khz or 60hz + 7k. My test signal is 60hz + 1khz 4:1 amplitude.
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