|
Computer Audio Asylum Music servers and other computer based digital audio technologies. |
|
|
|
Computer Audio Asylum Music servers and other computer based digital audio technologies. |
|
In Reply to: RE: Absolute Sound on Auralic Vega PLL posted by soundchekk on February 17, 2015 at 10:28:53:
The "patented Hyperstream" feature refers to the sigma-delta modulator. See the White Paper. There was also a video one of the designers gave on this subject. Interesting, because there were artifacts that some audiophiles heard that the designers didn't and that didn't show up on the measurements. As a result there were further improvements made in the modulator, presumably in the chip.
The biggest design challenge with the chip is the very high clock rate and the necessity to have very careful PC board layout and power for the chip and associated clock circuitry. I suspect this is one place where many designs go wrong. However, there are still some issues with the chip that require work around to get the best sound.
First, the ASRC needs to be bypassed, assuming the clock problems can be handled elsewhere. It's better than other ASRCs but it is not a complete solution since it is not bit transparent. At the very least, there is cross talk (admitted in the white paper) from the SPDIF input circuitry that makes it through the chip via ground bounce, etc., and pollutes the analog output. So even though "all" jitter may be removed by the ASRC there will still be input effects.
Second, the upsampling filters (particularly for Red book) are poor, just like almost all filters built into DAC chips. These need to be effectively bypassed by upsampling elsewhere, either in the DAC itself or in the computer. I upsample in the computer, e.g. to 176.4 or 192 before sending PCM to my Mytek. There are much better filters that can be selected, either by system balancing or (better) by adjusting to music genre or individual recording.
Third, the Hyperstream modulator is not as good as it might be. Many people have found that using Miksa's HQPlayer modulator to convert to DSD128 produces better sound than sending high rate PCM to a SABRE chip based DAC, such as my Mytek. Miksa claims he has some spectrum plots that show that his modulator has lower distortion, but I've not seen them. Unfortunately, Miksa's modulator is very compute intensive and some people may find their CPU speed to be a limiting factor.
This is just my personal take on this, and I have attempted to reach conclusions based on improvements when using my Mytek Stereo192-DSD DAC. There were a number of other tweaks that were needed to get around limitations of this DAC, especially bypassing the analog volume control circuitry and using the internal jumpers to reduce the output voltage. This enables me to go direct via balanced XLR to my amplifiers while needing very little digital volume reduction in the ESS chip, i.e. no bits in the input signal are lost at the settings I use for playback.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
This post is made possible by the generous support of people like you and our sponsors:
Follow Ups
- RE: Absolute Sound on Auralic Vega PLL - Tony Lauck 02/17/1512:44:00 02/17/15 (0)
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2024, Audio Asylum, all rights reserved ]
