Super Bit Mapping....any difference?

Discussion in 'Audio Hardware' started by Stateless, Mar 5, 2004.

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  1. Stateless

    Stateless New Member Thread Starter

    Location:
    USA
    Just had a quick question for the experts here. When I make copies of discs I use a SONY dual-disc component burner. The question I have is that occasionally I will come across a CD that is copy protected, or a CDR that cannot be copied digitally. (I always record in "CD Synchro" mode.) What happens is the burner will detect this, and in order to bypass the protection, the burner automatically switches recording from digital to the analog mode.

    My question is, does SBM matter in this case? Can it make difference in the sound when you are just making a duplicate of another CD in the "sychro" mode? I didn't even know SBM could work in this instance. :confused:

    Thanks for the help.
     
  2. fjhuerta

    fjhuerta New Member

    Location:
    México City
    I think SBM only adds dither to the original signal in order to try and save as much extra bit depth as possible from 20+ bit sources.

    So I'd guess you'd just get added dither, but no extra resolution.
     
  3. -=Rudy=-

    -=Rudy=- ♪♫♪♫♫♪♪♫♪♪ Staff

    Location:
    US
    I believe that direct digital copies ("synchro mode") are just bit-for-bit copies. SBM should only apply when copying from an analog source to digital. My dual-deck is a Sony also, but a cheaper model without the SBM.
     
  4. Stateless

    Stateless New Member Thread Starter

    Location:
    USA
    Exactly. But the thing is, when I thought I was making a synchro digital to digital copy, it would change to analog in the instances I mentioned. It's called the "Serial Copy Management System" which does not allow you to record digitally from a digitally recorded CDR. Now that I think about it, this was only happening when I would record from these types of CDR's. I just wanted to know if SBM mattered in these instances. It looks like you could add it if need be, but I don't even know if it matters with these digital CDR's.
     
  5. -=Rudy=-

    -=Rudy=- ♪♫♪♫♫♪♪♫♪♪ Staff

    Location:
    US
    I thought SBM was just an improved type of A to D converter. So yes, I would expect it to kick in whenever you're recording analog, including the analog mod of copying the copy-protected discs. Is there some kind of defeat switch for it, or not?
     
  6. fjhuerta

    fjhuerta New Member

    Location:
    México City
    I'd suggest taking it out. Increased dither levels are not beneficial if the source recording is 16-bit to begin with.
     
  7. Stateless

    Stateless New Member Thread Starter

    Location:
    USA
    Yes there is a switch. I think I recorded both ways when making a mix disc and not realizing it at first. I didn't notice any difference in the sound from the original source. Would I? I don't have a top of the line system.
     
  8. fjhuerta

    fjhuerta New Member

    Location:
    México City
    WW, the extra dither will be noticeable in very, very quiet passages.

    SBM is just extra noise. It's beneficial when the source recording has a higher dynamic range than 20 bits...
     
  9. Stateless

    Stateless New Member Thread Starter

    Location:
    USA
    Most Cd's are 20 bits or less aren't they? I know this is probably a basic question...
     
  10. JoelDF

    JoelDF Senior Member

    Location:
    Prairieville, LA
    All CD's are 16 bit - no matter what, or it would not follow the Philips/Sony redbook standard and play on any player.

    That why dithering comes into play with digital sources that are converted from higher bit depths.
     
  11. Stateless

    Stateless New Member Thread Starter

    Location:
    USA
    So I take it that SBM wouldn't even matter in the instance that I mentioned.
     
  12. fjhuerta

    fjhuerta New Member

    Location:
    México City
    No. ;)
     
  13. Stateless

    Stateless New Member Thread Starter

    Location:
    USA
    Thanks. :)
     
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