+ Reply to Thread
Page 5 of 5 FirstFirst ... 345
Results 41 to 47 of 47

Thread: 16 versus 24 bit files

  1. #41
    Join Date: Feb 2008

    Location: http://www.homehifi.co.uk

    Posts: 6,288

    Default

    Quote Originally Posted by drrd View Post
    With very good AD and DA conversion I think not only is 16 bit a completely adequate final file resolution but 44.1K is also completely adequate bandwidth. I'll record at 24 bit to allow for processing files but once that's finished I hear no difference when cutting off the 8 LSBs.
    Not all of us have the same hearing sensitivity and frequency response. Many people have a far larger ability to hear very minute audio details that others cannot detect. So cutting off the 8 least significant bits arbitrarily is not the way to go.
    One reason why oversampling of the CD data was first introduced (in the Marantz CD45 14Bit 4X oversampling CD player) was to attempt to recreate the missing bits that had been discarded at the A to D stage. But processing power at that time was not as powerful as it is today. So they had to use 14Bits instead of the full 16 bits of the CD format.

  2. #42
    Join Date: Jan 2010

    Location: Bristol, UK

    Posts: 85
    I'm Russell.

    Default

    Oversampling doesn't recreate missing bits. Oversampling gives increased bandwidth so that noise-shaping can be performed. Noise-shaping increases the resolution of the converter but biased to the lower frequency range, at higher frequencies noise-shaping worsens the converter performance. My converters run at 2.82 MHz and are 5 bit, with noise-shaping they can give up to 24 bit resolution in the audible frequency range but increasing quantisation error with frequency will make the higher end far worse than that, hopefully though that's outside hearing range. A 14 bit converter will have better resolution if it's oversampled 4x and noise-shaped to push quantisation errors out to where they aren't so audible but it doesn't do any magic recreation of data.

    If you have true 16 bit resolution for the whole range of 20Hz to 20KHz I would challenge anyone to listen to full-scale music and be able to hear extra bits. We are talking below -96dB at this point. You know 12 bit and even 8 bit digital sounds great if the music obscures the noise floor, they just have to be good bits for the whole audible frequency range, it's errors in AD quantisation and back again to analogue that the ear picks up on as sounding bad (see turntables as a good example of excellent linearity and poor S/N).
    Russell.

  3. #43
    Join Date: Feb 2008

    Location: http://www.homehifi.co.uk

    Posts: 6,288

    Default

    Quote Originally Posted by drrd View Post
    Oversampling doesn't recreate missing bits. Oversampling gives increased bandwidth so that noise-shaping can be performed.
    That's what it is used for now. But in that period of the 80's designers were experimenting with all sorts of techniques to try to "recover" discarded data from the A to D process, or from lack of processing power to extract the full 16 bit format from a CD. Oversampling was tried out with three reasons in mind. One was to simulate missing bits, one was to raise the then very sharp filtering frequency, and the third one escapes me. Its effectiveness in recreating extra bits was of zero value, so that intention was abandoned.
    Quite a few CD players were only 14 bit machines. One was even 12 bit, but I can't remember any more who released it.

  4. #44
    Join Date: Jan 2010

    Location: Bristol, UK

    Posts: 85
    I'm Russell.

    Default

    I'm sure there was a little marketing mumbo-jumbo back in the day (eg. Pioneer Legato Link) and maybe ideas were being tried without an exact understanding of why they did or didn't work. Havent heard any suggestion that the Phillips 14 DAC or even later 1-bit 256xOS designs were doing anything radically different to modern noise-shaped Delta-Sigma. These days the techniques seem to be fairly clear, at least the basic stuff that converter makers are prepared to divulge. The aim is better resolution and better linearity but not pretending to make a silk purse from a sow's ear.
    Russell.

  5. #45
    Join Date: Feb 2008

    Location: http://www.homehifi.co.uk

    Posts: 6,288

    Default

    Quote Originally Posted by drrd View Post
    I'm sure there was a little marketing mumbo-jumbo back in the day (eg. Pioneer Legato Link) and maybe ideas were being tried without an exact understanding of why they did or didn't work.
    I was one of the first engineers drafted in at the time (1983) from the repair industry to start testing and help the design engineers to come up with next generation solutions for CD playback. Philips and Sony were the first companies that needed my services, but others followed once I got known. This was well before any finished product was presented to any marketing team, and in many cases some machines and functions never made it to market. So what I am writing here is from an insider who was involved in the design of early CD equipment.

    Some of the features I miss because they were not implemented or withdrawn after implementation are:
    The track and CD album name on the display.
    Memorizing of the tracks that were most frequently played on a CD, with an option to then play your favourite selection or the whole CD.
    Selectable bitrate playback. This was to allow for suppression of low level noise on old analogue recordings that were converted for CD playback.

  6. #46
    Join Date: Jan 2010

    Location: Bristol, UK

    Posts: 85
    I'm Russell.

    Default

    That must have been interesting work, comparing what's known now with then though do you think it's reasonable that converters could possibly just make up valid data (that is audible) or do we now just have better resolving and especially more linear converters? I occasionally bought some slightly duff gear over the last 30 years or so but there have been some stand-out good ones. Still the trend with time has been that the sound quality has just got better, the CDs from 20-30 years ago now sound great and well produced red-book sounds difficult to distinguish from hi-res. Coming back to my original comment though I'd stick with well produced 16 bit 44.1 as a final format as being just about spot on.
    Russell.

  7. #47
    Join Date: Apr 2008

    Location: Warrington

    Posts: 3,451
    I'm Neil.

    Default

    The first 16 bits are infinitesimally more important than the 16 vs. 24 bit, so it is more important to focus on the DAC type IMO. I would take 16 bits from a well-implemented multibit DAC than a delta/sigma, oversampling, upsampling DAC etc. anyday. In reality too, no analogue system can physically play anything near 24 bit, the noise floor of real life limits the actual resolution to a maximum of below 21 bits. Where 24 bit or 32 bit, maybe even 64 bit is very useful is in the studio due to the additional headroom during digital editing. EDIT: I should add that if you're listening at over 100db volumes in the listening position, aside from going deaf, you'd might then gain an advantage with the extra dynamic range beyond 16bits...

    A little tin foil hat wearing person in me would think that companies pushing higher resolution may be inclined to work on these files and 'improve' them, or make them sound different...
    Last edited by Yomanze; 05-09-2013 at 19:00.
    Mana Acoustics Racks / Bright Star IsoNodes Decoupling >> Allo DigiOne Player >> Pedja Rogic's Audial Model S DAC + Pioneer PL-71 turntable / Vista Audio phono-1 mk II / Denon PCL-5 headshell / Reson Reca >> LFD DLS >> LFD PA2M (SE) >> Royd RR3s.

+ Reply to Thread
Page 5 of 5 FirstFirst ... 345

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •