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Up & Over Sampling... Continued

I recently emailed Kevin Halverson of Muse Electronics and asked him for a short layman's description of the difference between digital over sampling and upsampling. Kevin designed the Muse Model Nine and two ninety six that are on Stereophile's Class A+ list, and he is one of the top digital designers in the business. His entire response of 08/11/00 follows: "Dear Craig; Over & upsampling are both Sample Rate Conversion processes (SRC). Both accomplish the same basic goal of increasing the sample rate to increase the image rejection. Neither has any inherent advantage over the other, assuming both are done in a synchronous and integer fashion. The basic differentiation is that upsampling is an external process, oversampling is an internal one. In the case of the Model Two Ninety Six or Model Nine, the internal rates are 352.8 kHz for CDs and either 354 or 768 kHz for DVDs. The present trend towards the use of "upsampling" devices is to improve the performance of poorer performing converters (those with inadequate image rejection). In the case of either the Two Ninety Six or the Model Nine, neither would benefit from any additional image rejection as both already have more than is necessary. I hope this will give you a small amount of insight to the process and all the marketing hype being thrown about. Best Regards, Kevin Halverson". Craig.
garfish
garfish OP
1,840 posts
 
Sam...I agree with your post. Each of the manufactures implements this process differently, so they are going to sound different. BTW is HFNRR available on line? Cheers. Craig
bernstem
3 posts
 
It is no surprise that different CD players made by different manufacturers are going to sound different. What made the DCS machine in this case sound better to this particular listener may have nothing to do with upsampling versus oversampling. The analog output stages of these machines are one strong alternate source of sonic differences. I for one don't really know how they could differentiate the sound of upsampling from all the other factors that might affect the sound.
kkirkpa1805
48 posts
 
The drift I get from articles in the major press is that "upsampling" improves digital sound by allowing the use of gentler filters when converting to analog. Seems the cruddy sound of "redbook" digital results from the radical "brickwall" filtering used to remove anything over 20Khz.
pls1
432 posts
 
The audio stages do make a difference. The new MSB Platinum DAC has NO audio output stage in balanced mode and can drive my monoblocks directly. (It also rate converts and has selectable filters.)The lack of an audio stage is part of the reason that the Platinum sounds better than my old Theta Pro Gen Va upgraded to 24/96. However, the professional digital firms like dCs, Z-Systems and SigTech also pride themselves on the implementation of subtly different algorithms. That is also part of why the upgraded Theta sounded better than the non upgraded Theta. When I got a chance to borrow the dCs multi rate converter and the matching DAC, my Theta sounded better with the dCs converting to 24 bit 96. Even just the Z-systems set to output 24 bit dithered made the Theta sounded better. I've played around with a fiar number of combinations in the digital chain and have concluded that the additional processing power available now due to Moore's Law allows for significant improvement of the sound from a Red Book CD. However, I don't think that there is presently a simple specs driven explanation which means you have to listen to the specific piece of gear. Anyone who gets a chance should listen to the dCs, MSB Platinum, and other advanced digital domain devices to hear the very noticable improvements.
greysquirrel
62 posts
 
Bernstem, I had the same opinion about the HFNRR article. They basically compared two different CD players and concluded they liked one better than the other. Not much different than if we all compared two different CD players and found the one with the pink flamingo painted on top sounded better (more natural). Was it due to the pink flamingo? I say that not to inflame anyone, only to make the point that there are so many "levers" to adjust the sound of a player. In the hands of great designers like Kevin Halverson and Jeff Kalt, great sounding components can be made. Increase the budget (parts quality, R&D etc) and even better sounding components will follow.
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