Sure. Here is the comparison to Gustard DAC-X26 without this problem (in pink):Would it be too much to ask to run this test on a DAC that does not exhibit this issue for the purpose of comparison?
Sure. Here is the comparison to Gustard DAC-X26 without this problem (in pink):Would it be too much to ask to run this test on a DAC that does not exhibit this issue for the purpose of comparison?
Thank you Amir! If I am interpreting this graph correctly, it appears that the ESS hump distortion is below -100db throughout the volume range. According to your "Audibility thresholds of amp and DAC measurements" post, the lenient limit for IMD is -66db and the strict one is -120db. This means that the devices with ESS hump are actually closer to the strict limit than to the lenient limit which is already supposed to be inaudible. Therefore, except for striving for engineering perfection, this actually appears to be an absolute non-issue in terms of the impact on the sound fidelity of these devices.Sure. Here is the comparison to Gustard DAC-X26 without this problem (in pink):
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Those are levels in dBV, not ratios as I typically show. When the generator is at -30 dBFS, the distortion is at -100 dB. Assuming for now that dBFS = dBV (probably not but good enough for this), then the gap is 70 dB. Or put inversely, as a ratio it would be -70 dB. So it is not that low.Thank you Amir! If I am interpreting this graph correctly, it appears that the ESS hump distortion is below -100db throughout the volume range. According to your "Audibility thresholds of amp and DAC measurements" post, the lenient limit for IMD is -66db and the strict one is -120db. This means that the devices with ESS hump are actually closer to the strict limit than to the lenient limit which is already supposed to be inaudible. Therefore, except for striving for engineering perfection, this actually appears to be an absolute non-issue in terms of the impact on the sound fidelity of these devices.
Those are levels in dBV, not ratios as I typically show. When the generator is at -30 dBFS, the distortion is at -100 dB. Assuming for now that dBFS = dBV (probably not but good enough for this), then the gap is 70 dB. Or put inversely, as a ratio it would be -70 dB. So it is not that low.
I am not sure that I understand this properly. Using the same approach for Gustard DAC-X26, when the generator is at -30 dBFS, the distortion is around -117 dB. That means that the gap is 87 dB, so as a ratio it would be -87 dB. Does that mean that when the signal is at -30 dB, the audible IMD distortion is at -87 dBFS or at -117 dBFS for Gustard DAC-X26?
It is not the same test. It looks similar but is different. My standard tests are ratios so you can do the math as you are doing. The test posted in this thread is a voltage expressed in dB. The ratio is NOT to the generator level but to one volt (dbV).Using the same approach for Gustard DAC-X26, when the generator is at -30 dBFS, the distortion is around -117 dB.
The graph was THD to show that this is not just intermodulation distortion. For your question, you can use the IMD measurement and there, it is expressed as a ratio to input level so you can do your math:Does that mean that when the signal is at -30 dB, the audible IMD distortion is at -87 dBFS or at -117 dBFS for Gustard DAC-X26?
ESS having a bump in their IMD due to their internal jitter eliminator/ASRC
bump, not hump
One would need a way to turn the Hump on and off to know the effect to know if it is or isn't audible in listening tests. That is impossible right now.
Sure. Here is the comparison to Gustard DAC-X26 without this problem (in pink):
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I did some tests with different clocks, and noticed THD improvement from noname 100MHz 3.3V OSC to SiTime SiT8209 and further with 50MHz Epsol crystal + internal DAC's OSC. The biggest improvement I got when replaced 100MHz OSC to SiT8209, don't remember exactly because I made many others modifications as well to improve THD, I think at least from .001% to .0006% step down only due to SiT8209. And Epcos standard crystal+internal 9038q2m oscillator reduces THD up to .00045%(or .00025% after THD_COMP tweaking) on my proto-board, which is highly optimized for a min size(USB dongle, I posted the pic here). Of course, I glad to get such a perfect clock for 1/30 of SiT8209 cost but 50MHz simply don't catch Fs=192, only <=96, so I need to use 100MHz crystal anyway. Unfortunately, 100MHz Xtals available in 5032 or bigger case.. It seems 9038q2m datasheet has mistake regarding 100MHz as max Xi, it rather min or the only single valid frequency, at least for SPDIF at 192.
Great, professional manual!Would be interesting to see the measurements of the Accuphase DC-950 DAC based on the 9038Pro chip.
http://accuphase.com/cat/dp-950_dc-950_e.pdf
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