JB920 digital in/out 16/20/24 bit question

[wildgoose]

My JB920 has option to set the bits for digital in/out between 16, 20, and 24. The default is 20.

Now if I want to make an "as pure as possible" copy of a CD, should I set it to 16? Since CD is 16bit?

What about if I am copying an MD (to a MZ-R50 digitally)? Should I set both in/out to 16-bit to bypass any upconversion/down conversion in the progress?

If that is the case, what is the point of providing 20bit and 24bit output? When I am listening to MD? When I am encoding from analog source?

Thanks!

[MDX-400]

Yeah set it to 16-bit if you're using a normal CD with a normal CD player's digital output

Going to an R50, I think 16-bit would be correct though I'm not 100% sure.

The longer word lengths are for equipment that can properly handle the extra bits. Any MD equipment with "Wide Bit Stream" can make use of either 20 or 24 bit information. I'm not sure exactly when portables started using this, but I don't think the R50 had that feature.

Also if you're using the digital out of the deck to connect to a receiver or something, setting the output to 24-bit is going to be better as well.

Note that no matter which way you set it, you're probably not going to hear any difference though, lol.

On my JB920 I leave my input at 16-bit and my output at 24-bit and it works fine for me (though I never record from the JB920 to another device, I just have the output connected to my receiver).

[wildgoose]

Strangely when I toggle the D.OUT bits using the remote, there isn't any pause/interruptions in the sound from the receiver. Makes me wonder if it's actually doing anything. My receiver is a Denon 3803 and I can't get it to actually display the bit depth info..

Is the MD format itself 16bit or 24bit? IF it is 16 bit, does that mean the JB920 will interpolate the signal into 24bit, does the encode, and finally transform it again to 16bit and store it?

Or perhaps the question doesn't even make sense. MD is a compression format, therefore have no bit-depth. Some kind of a formula to approximate a specific curve. If there are more bits to represent the curve in the first place, then the approximation may be better. If that's the case, then perhaps the IN.OUT should be both set to 24bit.

I don't know if the R50 can handle the wider bit or not. My receiver has 2 optical out. One is connected to the JB920, the other I connect it to the R50. I have recorded digitally to the R50 from the JB920 through the receiver. I am going to try tonight to copy a MD using 24-bit out to the R50...

[MDX-400]

My STR-DA4ES shows "STREAM = PCM 23BITS [44kHz] BITRATE=2028kbps FS=44kHz" when playing back on the "24-bit" setting on the JB920. It changes instantly to "STREAM = PCM 20BITS ... BITRATE=1764kbps" and "STREAM = PCM 16BITS ... BITRATE=1411kpbs" when I change the setting on the JB920. There is no pause or gap/skip in the music at all when this happens, it just changes on the receiver when I change it on the MD deck.

So it is definitely doing what it's supposed to. (Not sure why it actually shows 23 bits instead of 24, but it's still working...)

The word length settings affect the inputs and outputs, not the actual recording of the MD. On the JB920 the recording will always be with Wide Bit Stream, regardless; however, if 20 or 24 bits are available for input, it's better to use those if possible.

The R50's input will most likely accept 20 or 24 bit digital input fine, however my remark was more regarding whether it actually makes any real use of them (whether it has Wide Bit Stream) or not...

[ZosoIV]

MD's, like all other lossy codecs, don't have a bitdepth until decoded to PCM. The compressed data on the disc is in floating-point. If playing back an MD recorded from a CD, the output signal will at best be equivalent to 16 bits because that's what was put into the encoder - regardless of your output settings. All that will be up past the 16th bit is silent padding, quanitization noise, or both.

The only time I could see using a higher output on the JB920 is for discs recorded via the analog or mic in, which *may* have slightly more than 16-bits equivalent resolution in terms of dynamic range (though very unlikely - tapes and records certainly don't, and who here has a mic that can record a 108dB signal without distortion?). If you're really lucky and do an outstanding analog recording on a deck with very quiet inputs, the result could, at certain frequencies, be better than 16-bits. Possible in theory, doubtful in practice. And that’s to say nothing of the effects of ATRAC, which introduces a lot of pre-echo and quantization noise at certain frequencies, as well as a reduction in dynamic range. In short, the output setting should have no discernable effect on sound quality in a blind comparison.