What is CD upsampling? Do I need it?

Discussion in 'Archived Threads 2001-2004' started by james e m, Nov 24, 2002.

  1. james e m

    james e m Second Unit

    Joined:
    Jun 3, 2001
    Messages:
    497
    Likes Received:
    0
    Trophy Points:
    0
    I'm looking to buy a new cd player and I'm leaning toward the 555ES but it doesn't have the cd upsampling I keep hearing so much about. What is cd upsampling? Does it make a huge difference? I'm simply looking for the best 5 disc cd player for 2 channel stereo, right now I have no real interest in SACD. Should I wait until someone offers a 5 disc player with it?
    Thanks...
    James
    ps If it matters I have a Sony DA5ES with Studio 100s. Thanks!
     
  2. Philip Hamm

    Philip Hamm Lead Actor

    Joined:
    Jan 23, 1999
    Messages:
    6,873
    Likes Received:
    2
    Trophy Points:
    0
    My Technics DVD-A10 does upsampling (they call it "remastering") and I can't tell the difference. SACD and DVD-Audio both sound great, though. A little bit better than CD which sounds great, too.
     
  3. KeithH

    KeithH Lead Actor

    Joined:
    Mar 28, 2000
    Messages:
    9,413
    Likes Received:
    0
    Trophy Points:
    0
    James, upsampling is a technique whereby dither, which is noise, is added to increase the word length and sampling frequency of the CD from 16/44.1 to other values, most commonly 24/96 or 24/192. Upsampling is a controversial subject as to whether it improves the sound quality or not. Some believe swear by upsampling, while others deride it. On high-end CD players and outboard DACs, upsampling can be turned off, which then allows for comparison to 16/44.1.

    At present, there are no carousel changers available with upsampling. Upsampling is generally included in high-end devices, and there are really no high-end changers available now, save for the Sony 'C555ES. Some audiophile-oriented companies have made changers in the past (e.g., Cal Audio Labs, Anthem, Rotel, and Arcam), but they did not include upsampling. In event, you could always pair a changer with an upsampling DAC such as the Musical Fidelity A324, which sells for $1200. I realize that the extra cash outlay may not be desirable.

    Like Philip, I too have the Technics DVD-A10 first-generation DVD-Audio player with the "ReMaster" feature. I have not found it to make a difference. Most print reviews I read of the 'A10 reported CDs sounding better with the feature turned off. All in all, the 'A10 is an average CD player in my opinion. Matsushita offers the ReMaster feature in its current DVD-Audio players (e.g., 'RP82 and 'RP91), but I don't know if the implementation is any better than what I have observed with the 'A10.

    A player you might to consider, though it is not a changer, is the Philips DVD-963SA. It will supposedly be available in early 2003. It will be a single-disc progressive-scan DVD player with SACD playback and 24/192 upsampling of CDs. I don't know if the upsampling feature can be turned off, and of course, I don't know how the '963SA handles upsampling. The '963SA will offer the latest Faroudja deinterlacing chip, so it should not show the chroma bug. At a retail price of $500, the '963SA looks like a lot of player. J&R Music World (1-800-221-8180) is taking pre-orders for $400.

    Finally, I agree with Philip in that SACD and DVD-Audio are better than CD. However, I would say that at their best, SACD and DVD-Audio are more than just a little better than CD. It depends on the disc. Anyway, if you can find a Sony 'C555ES, grab one. SACD aside, it is an outstanding CD player. Build quality is top-notch as well. Many people have said that the 'C555ES is getting tough to find these days. You may have an easier time tracking one down through a brick-and-mortar dealer than one of the discount mail-order dealers.
     
  4. John Geelan

    John Geelan Screenwriter

    Joined:
    Oct 11, 2000
    Messages:
    1,087
    Likes Received:
    0
    Trophy Points:
    0
     
  5. ReggieW

    ReggieW Screenwriter

    Joined:
    Mar 6, 2001
    Messages:
    1,571
    Likes Received:
    1
    Trophy Points:
    0
    When I was shopping for a player a few months ago I did a comparison between the Panny RP-82, which upsamples, and the Denon 1600 which has good Burr-Brown DAC's but doesn't upsample, and found the 1600 to be the superior audio player with redbook CD'S and DVD-A, hence, I went with the 1600. As far as I can tell, the Panny's upsampling feature did little or nothing to improve the sound imho. I have always been suspicious of upsampling and have found it gimmicky. I mean, there are some out there who believe that the redbook CD of Hotel California when upsampled to 192khz can sound as good as the DVD-A track remastered at 192khz. I can tell you that it isn't even close - the DVD-A destroys it. Needless to say, until I've seen some real results, I will continue to be suspicious of the upsampling phenomena.

    Reg
     
  6. KeithH

    KeithH Lead Actor

    Joined:
    Mar 28, 2000
    Messages:
    9,413
    Likes Received:
    0
    Trophy Points:
    0
    Reggie said:

     
  7. LanceJ

    LanceJ Producer

    Joined:
    Oct 26, 2002
    Messages:
    3,168
    Likes Received:
    1
    Trophy Points:
    0
    PCM uses what's called a "brick-wall" filter that filters out unwanted digital noise past 20kHz that results from the digital to analog conversion process. The brick-wall term means that this filter acts very quickly to cut off frequencies past 20kHz--a graph would show a very steeply descending line. Well, this also introduces some sonic problems of its own, unfortunately in those very delicate audible upper frequencies. Sort of a shock wave effect, if you will, when the bad frequencies slam into that filter. The audibility of these sonic problems varies among listeners though. But they are present.
    But if a higher sampling rate is used, that brick-wall filter can set at a higher frequency, further away from the audible range of sounds, and it can be designed with a less severe cut-off slope (that graph line would taper off more gently) which doesn't mess so much with the frequencies below it. Hence, using 192kHz DACs. BTW, higher sampling rates improve the sound mostly because they capture more of the original sound, i.e. they take a more finely detailed picture of the microphone's waveform. And not so much because their upper frequency limit is higher than a CD's.
    That Nyquist limit thing is correct in that using twice the sampling rate of the highest frequency you want to reproduce does work (using a sampler set at 44kHz will capture a 20kHz waveform), BUT it fails to capture all the finer details that ride along with that 20kHz 17kHz/15kHz, etc. waveform. (Here comes by hi-rez format bias! If you go to Panasonic's dvd-audio site, click on "About dvd-audio", then "How it works", then "sampling and quantization" they have a concise animation of what I am talking about: http://www.panasonic-europe.com/dvdaudio/ )
    That "remaster" thing is a little different. It is a lot like Pioneer's "Legato Link" feature, where a circuit manufactures the higher frequencies above CD's cut-off point (or any source's cut-off point actually)--based on the frequencies that ARE present--that are supposed to contribute to sonic realism. Obviously, this means frequencies above the audible limits for a CD, but the theory is: 1) they subtly affect the lower ones, through kind of a daisy-chain effect; 2) a person can subconsciously detect these ultrasonics, in turn improving the listening experience. That's the theory anyway! to me, #1 sounds more plausible. LJ Personally, any circuit that is "making up" sound worries me (reviewers said exactly the same thing about Legato Link back in the early 90's). But it might have one good use: Panasonic's SA-HE200 receiver has this feature and they say it can help MP3's sound better. Since MP3 already hacks apart the original signal anyway, some extra made-up stuff is no big deal & maybe it would help those things sound better!
    LJ
     
  8. KeithH

    KeithH Lead Actor

    Joined:
    Mar 28, 2000
    Messages:
    9,413
    Likes Received:
    0
    Trophy Points:
    0
    Lance said:

     
  9. Craig_Kg

    Craig_Kg Supporting Actor

    Joined:
    Feb 25, 2002
    Messages:
    768
    Likes Received:
    0
    Trophy Points:
    0
    With no upsampling, you'd get the Chipmunks at low volume.

    As well as the dithering to extend values, interpolated values are created in the upsampling process to create a pseudo higher sampling rate. This lets a gentler filter (or higher freq brickwall) be used on the decoder output. Oversampling is evry similar except the resolution isn't scaled up - just the sampling frequency.
     
  10. Tom Moran

    Tom Moran Agent

    Joined:
    Oct 9, 2002
    Messages:
    48
    Likes Received:
    2
    Trophy Points:
    0
    Upsampling does nothing other than make up stuff that was not on the original recording, period. Some things might sound better with a little luck and many are likely to sound no different or even worse.
    Getting more information on the disc makes sense to me...trying to get more than what is there off of the disc does not... [​IMG]
    Tom
     
  11. Chas_T

    Chas_T Supporting Actor

    Joined:
    Jun 1, 2002
    Messages:
    758
    Likes Received:
    0
    Trophy Points:
    0
    Reggie:
     
  12. Craig_Kg

    Craig_Kg Supporting Actor

    Joined:
    Feb 25, 2002
    Messages:
    768
    Likes Received:
    0
    Trophy Points:
    0
     
  13. ReggieW

    ReggieW Screenwriter

    Joined:
    Mar 6, 2001
    Messages:
    1,571
    Likes Received:
    1
    Trophy Points:
    0
    Craig..........

    I understand your technical points, however, many of us here in this thread still fail to be impressed with upsampling, hence there are many examples of components that don't upsample producing better audio quality from sources than components that do. I will continue to maintain an open mind on the subject, but until I hear the evidence, I will not consider purchasing one component over another simply because one may upsample. This is imho of course.

    Reg
     
  14. KeithH

    KeithH Lead Actor

    Joined:
    Mar 28, 2000
    Messages:
    9,413
    Likes Received:
    0
    Trophy Points:
    0
    Conceptually, I have a problem with what upsampling is doing or trying to do. However, I am keeping an open mind to upsampling, as I have limited hands-on experience with it. I still am considering the addition of the 24/192 upsampling DAC to my Ah! Njoe Tjoeb 4000. The few reviews I've read of it have been positive.
     
  15. Craig_Kg

    Craig_Kg Supporting Actor

    Joined:
    Feb 25, 2002
    Messages:
    768
    Likes Received:
    0
    Trophy Points:
    0
    I don't think upsampling has any theoretical benefit over oversampling (which all non-upsampling CD players now do). I guess didn't make that clear enough in my previous post.

    The practical advantage is that a manufacturer can use the same DAC that is used for DVD-A which may be more affordable these days than a pure redbook DAC (plus it can make for a more versatile player).
     
  16. LanceJ

    LanceJ Producer

    Joined:
    Oct 26, 2002
    Messages:
    3,168
    Likes Received:
    1
    Trophy Points:
    0
    Maybe I was too wordy:
    When you process a CD's 44.1kHz/16bit signal through a 192kHz/24bit DAC, the convertor is not "making up" any information. The resulting digital word, instead of just a 16bit length and 44,100 samples per second, now consists of a 24bit word and 192,000 samples per second.
    BUT, in that 24bit word, all the bits past the 16th bit are set to "0". So the CD's word still has the same value. The number of samples? Roughly 3/4's of that 192kHz signal is redundant information. So the rest of the DAC just thinks the resulting bitstream is just representing a waveform without much detail, and just processes it as any other 192kHz/24bit signal. But all this is needed so that the brickwall filter's filtering point can be set way above the audible frequencies, as I said before, to avoid affecting the frequencies of 20kHz & below.
    Again, there is no new information being created--this is strictly a filtering issue.
    LJ
     
  17. Ted Lee

    Ted Lee Lead Actor

    Joined:
    May 8, 2001
    Messages:
    8,390
    Likes Received:
    0
    Trophy Points:
    0
    lance (et al) - thanks to your explanation, i now understand how a brick-wall filter works. that was a great post. [​IMG]
    who the heck is this nyquist guy? [​IMG]
     
  18. KeithH

    KeithH Lead Actor

    Joined:
    Mar 28, 2000
    Messages:
    9,413
    Likes Received:
    0
    Trophy Points:
    0
    Lance, that makes perfect sense to me. Thanks. It's logical. This is exactly how I would have handled upsampling were I developing audio from scratch. [​IMG]
     
  19. LanceJ

    LanceJ Producer

    Joined:
    Oct 26, 2002
    Messages:
    3,168
    Likes Received:
    1
    Trophy Points:
    0
    Nyquist was a theoretical(?) mathmetician. Er, this is about the extent of my knowledge about him as it applies to audio! [​IMG] Google or Alta Vista would be your best bet for detailed info about him.
    LJ
     
  20. james e m

    james e m Second Unit

    Joined:
    Jun 3, 2001
    Messages:
    497
    Likes Received:
    0
    Trophy Points:
    0
    Gentlemen thanks for the great post, it contains a wealth of knowledge and more importantly I enjoyed reading it. [​IMG]
    James
     

Share This Page