The Weak Link: Cd Player To Himd

[rlmoss]

I'm in Taiwan with a PCD with headphone. I didn't bring my CDs but the public library has good collection. SONY'S new MZ RH10 has USB and line in (analog, optical).

I would think the cleanest signal in would be an optical digital signal from "black box" --sorry I don't know what black-box would be but imagine it is digital signal from a PC before the sound-card turns into analogue. Or the digital feed out of transport before it goes to a DSP.

I don't have audio or computer audio equipment of that caliber in Taiwan. If my fall back is using the line out / headphone out from the Phillips PCD, I assume the HiMD will have whatever colorations the PCD adds or replicate the limitations.

Are there any other ways to get a more faithful replication of the CD.

Many thanks,

Richard Moss

Taichung 400

Taiwan ROC

[The_Stamp]

if you say you can use your computer's soundcard, you can transfer the CD digitally via Sonicstage with no degredation in PCM mode. As far as i know, CD to PCM has no degredation whatsoever.

[A440]

Forget SonicStage for this purpose, use SimpleBurner, downloadable here.

http://forums.minidisc.org/index.php?showtopic=5552

Connect via USB, open Simple Burner, pop in CD and transfer.

[MDGB2]

Technically, transfering music via digital Coaxial cable is superior to optical cable.

Can't really do that however until someone makes a proper Hi-MD deck...

I currently use Simple Burner 2E for transfering CDs in Hi-SP mode, SonicStage SUX!!!

[KrazyIvan]

Technically, transfering music via digital Coaxial cable is superior to optical cable.

Can't really do that however until someone makes a proper Hi-MD deck... 

I currently use Simple Burner 2E for transfering CDs in Hi-SP mode, SonicStage SUX!!!

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I am curious, How can one digital format be superior to another digital format if digital is digital? Asumming the bit-rate is the same, of course.

Edited May 6, 2005 by KrazyIvan

[arb226]

I am curious, How can one digital format be superior to another digital format if digital is digital? Asumming the bit-rate is the same, of course.

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Depends on whether compressed or uncompressed, and if compressed, what compression algorithm it uses. MP3 is digital but it's compressed. CD is digital but uncompressed. Minidisc uses compression but sounds much better than CD.

[MDGB2]

I am curious, How can one digital format be superior to another digital format if digital is digital? Asumming the bit-rate is the same, of course.

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Coaxial cable (75ohm) has always been considered "superior" to Toslink (optical) for recording digital music. Don't know why as they're both digital, although they do transfer the signal differently (Coax - Electrical, Toslink - Optical)

[KrazyIvan]

Coaxial cable (75ohm) has always been considered "superior" to Toslink (optical) for recording digital music. Don't know why as they're both digital, although they do transfer the signal differently (Coax - Electrical, Toslink - Optical)

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No offense against you but that sounds like a bunch of hocus pocus snake oil to me. Digital is just one's and zero's. It cannot be reproduced any less or any more, unless you get some sort of data corruption. Where I can see the sound being affected is in the amp or any sound shaping devices like EQ.

The only advantage to coax that I can see is the strength of the cable.

arb226: Yes, that is why I assumed the bit-rates are the same.

Again, I don't want to offend anyone, that is not my intention.

[jadeclaw]

There are claims, that a coax digital has less jitter, being therefore more precise than optical transfer,

resulting in cleaner sound, more defined soundstage and clearer highrange details.

However, the transmitter and receiving circuits are identical for both and the chips used for that have a signal conditioner,

which removes the jitter anyway, as the following circuits need everything precisely synchronised.

Yes, KrazyIvan, it is snake oil indeed.

[physya]

No offense against you    but that sounds like a bunch of hocus pocus snake oil to me.  Digital is just one's and zero's.  It cannot be reproduced any less or any more, unless you get some sort of data corruption.  Where I can see the sound being affected is in the amp or any sound shaping devices like EQ.

The only advantage to coax that I can see is the strength of the cable.

arb226: Yes, that is why I assumed the bit-rates are the same.

Again, I don't want to offend anyone, that is not my intention. 

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Digital is digital, but you may introduce digital noise (just electric fluctuations and EM pickup from surrounding) - new ones and zeros during transfer.

So, unless you use a sophisticated error correction/rejection protocol (e.g. FTP reads back the packets and checks for the error bit) you gonna have digital noise in your recording.

[KrazyIvan]

Digital is digital, but you may introduce digital noise (just electric fluctuations and EM pickup from surrounding) - new ones and zeros during transfer.

So, unless you use a sophisticated error correction/rejection protocol (e.g. FTP reads back the packets and checks for the error bit) you gonna have digital noise in your recording.

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In that case I would see digital coax as being more suseptible to EM since it is copper/metal cable. Optical is fiber, so impervious to EMI. This would leave the recorder and player doing all the EMI reception. In that case it would not matter what you are using to record. Whatever the case, I use coax and optical on a regular basis, just different situations. I don't have complaints on either.

[LupinIV]

Coax vs Optical? This is crazy

Digital is digital (to quote physya). They deliver 0 and 1. how can one have higher or better frequency response than the other since there is no frequency based carrier?

Also, digital noise is not an issue. Even if there is a certain amount of noise introduced to the transmission, it would completely be obliterated by the "same" digital corruption introduced by processor decoding, memory storage and DSP convertion that are all, guess what, digital!!!

So, if you believe the bogus, then any digital movement of data (optical, cable, wireless) should screw your data and consequently become useless after many transfer.

Try transferring data trough optical or coaxial many times, the digital noise and data loss will never be always located on the high or low or mid range, since a loss or corruption of data by noise is RANDOM thus affecting the data in different location at different time.

Imagine a train transporting a car broken down to little pieces and distributed on 100 carts. If the train carts are corrupted randomly, then when you assemble the machine at the end, the "errors" will be located in "Random" places, not always on your tires, or frame, or whatever....

Think! Think! Think!

Cheers

Good luck.

[KrazyIvan]

Coax vs Optical? This is crazy

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I think that is what I said a few posts up.

[physya]

I think that is what I said a few posts up. 

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Well folks, this is not as simple as it looks.

I mentioned error correction and rejection buil into any file transfer protocol. The actual amount of information is about 1/5 of all traffic - the rest is used for the error correction. I don't think the recording uses same thing.

Now, certainly noise have frequency dependence. Usually it is so called 1/f noise, so your low frequency is more affected. On the other hand, the surrounding is full of high frequency stuff and tends to have elevated noise at higher frequencies.

Coaxial cable is a pretty good shield up to few MHz frequencies above which you have to use solid stainless steel coax with SMA connectors to completely suppress noise.

I can actually beleive that coaxial is better than optical, because transformation of electric to optical and backwards is potentially a source of errors.

[lightbulbjim]

Ok, someone go do a double blind test.

Don't forget to test it without any cable attached at all. That way we'll get a fair and even response

In all seriousness, I think the differences are more practical than anything else. For instance, coaxial can go round sharp corners without damage easier than optical.

And you could run optical cable a lot further than coaxial for the equivilent signal loss, but that would only start to occur once you had cable runs of several kilometres.

Meh, just enjoy the music

[dex Otaku]

No offense against you     but that sounds like a bunch of hocus pocus snake oil to me.  Digital is just one's and zero's.  It cannot be reproduced any less or any more, unless you get some sort of data corruption.   Where I can see the sound being affected is in the amp or any sound shaping devices like EQ.

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Coax or optical for short cable runs are fine. Both use nearly the same standards to talk to other devices as the AES/EBU interface [digital over balanced cables, usually XLR line cables].

Coax is considered superiour because plastic fibre can cause jitter in the bitstream, which can't happen with an electrical cable. Fibre, when bent or looped, causes minute refractions and reflections both inside the material carrying the light and from light reflecting off the walls of the fibre itself [which, at worst, causes something close to standing-wave interference patterns]. Given sufficient bends, the signal can be degraded sufficiently to cause unrecoverable errors.

In practise, this is almost never experienced.

Another thing to keep in mind about "digital is digital":

MD and HiMD recorders, to my knowledge, resample their input to 44.1kHz [and have been doing so for years]. Nominally this is to convert 32kHz or 48kHz streams to MD's 44.1kHz.. however, in order to maintain time accuracy, even 44.1kHz streams are resampled; all streams, regardless of sampling rate, are reclocked. This means that recording with the optical in is -never- bit accurate, probably even if using PCM mode with HiMD.

Some have said this accounts for MD's "better sound" than even the source a recording came from.

Again, in practise, the chance that anyone will notice any effect from this is close enough to nil to be nil itself.

[physya]

...

In all seriousness, I think the differences are more practical than anything else. For instance, coaxial can go round sharp corners without damage easier than optical.

And you could run optical cable a lot further than coaxial for the equivilent signal loss, but that would only start to occur once you had cable runs of several kilometres.

Meh, just enjoy the music 

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...and (to be completely paranoic) then you should make sure that both devices properly grounded and there is no ground loop. (not a joke - there is NO good ground in a normal household). ... and yes, you want to make sure that cables are properly terminated at 75 or 50 Ohms...

[KrazyIvan]

Meh, just enjoy the music 

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I like that!

[1kyle]

Any signal can get corrupted -- extra bits can get inserted / changed due to magnetism / electrical or other interference --ever tried watching Satellite TV in a weakish reception area when it's raining heavily or using one of those TV senders when next door has got a microwave switched on.

Fibre optical cable is actually likely to be better shielded against this type of interference than coax since decent fibre optic cable doesn't actually carry a "traditional electric current" like copper wire etc.

So whoever came out with Coax is better than optical needs to go back to physics 101.

Coax appeared long before RELIABLE optical cable appeared which is probably why it was the preferred medium --and of course you can use longer cable lengths without needing repeater amplifiers (another area where signals can get corrupted).

However if you can assume either cable type is losseless and no signal can get corrupted by outside influences then a digital signal is a digital signal pure and simple -- like copying a data file on your computer from one disk to another or to an external drive or even a DVD. You expect your data to be the same whether it's on a CD or hard disk

--same with a digital music signal -- the mechanism used to get it from the source to the destination shouldn't normally matter.

So the whole argument here should be left "in the Realms of Bovine Scatology".

Cheers

-K

Edited June 5, 2005 by 1kyle

[physya]

Indeed, optical is much better ... for trans-Atlantic communication. At home, the conversion of electric to optical and cable bending are bigger problems than electric noise. (Good) coaxes are good up to MHz frequencies.

As for CD vs HD etc. You again forget the error correction built into any copying process.

I think the following will be useful for all this "digital is digital" discussion:

(taken from CD-Recordable FAQ)

-------------------------------------------

Subject: [2-17] Why don't audio CDs use error correction?

(2001/08/01)

Actually, they do. It is true that audio CDs use all 2352 bytes per block for sound samples, while CD-ROMs use only 2048 bytes per block, with most of the rest going to ECC (Error Correcting Code) data. The error correction that keeps your CDs sounding the way they're supposed to, even when scratched or dirty, is applied at a lower level. So while there isn't as much protection on an audio CD as there is on a CD-ROM, there's still enough to provide perfect or near-perfect sound quality under adverse conditions.

All of the data written to a CD uses CIRC (Cross-Interleaved Reed-Solomon Code) encoding. Every CD has two layers of error correction, called C1 and C2. C1 corrects bit errors at the lowest level, C2 applies to bytes in a frame (24 bytes per frame, 98 frames per sector). In addition, the data is interleaved and spread over a large arc. (This is why you should always clean CDs from the center out, not in a circular motion. A circular scratch causes multiple errors within a frame, while a radial scratch distributes the errors across multiple frames.)

If there are too many errors, the CD player will interpolate samples to get a reasonable value. This way you don't get nasty clicks and pops in your music, even if the CD is dirty and the errors are uncorrectable. Interpolating adjacent data bytes on a CD-ROM wouldn't work very well, so the data is returned without the interpolation. The second level of ECC and EDC (Error Detection Codes) works to make sure your CD-ROM stays readable with even more errors.

It should be noted that not all CD players are created equal. There are different strategies for decoding CIRC, some better than others.

Some CD-ROM drives can report the number of uncorrected C2 errors back to the application. This allows an audio extraction application to guarantee that the extracted audio matches the original. The Plextor UltraPlex 40 is one such drive.

See http://www.cdpage.com/dstuff/BobDana296.html for an overview of error correction from the perspective of media testing. If you really want to get into the gory technical details, try http://www.ee.washington.edu/conselec/CE/k...95x7/iec908.htm

[dex Otaku]

So whoever came out with Coax is better than optical needs to go back to physics 101.

There are at least a few thousand audio engineers who would dispute this, from experience in practise, not theorising.

Not that they'd dispute physics, just that they'd dispute which works better.

As for CD vs HD etc. You again forget the error correction built into any copying process.

True, but the bitstream going over AES/EBU, SPDIF coax or optical does not contain this kind of error correction. CD's error correction is part of reading the stream from the disc. What comes out the digital pipe does not work the same way.

More info? Look up SPDIF on wikipedia.

[skyther]

Minidisc uses compression but sounds much better than CD.

Errr..... wtffffffffffffffffffomgbbq! (sorry, am I allowed to say that? ) Man I never thought I'd hear anyone say that again... I sure hope that placebo remark about MD sounding better than CD on one of md.org's pages has been removed.

Lossy compression means fidelity gone out the window. MD sounding MUCH better than CD is just so wrong. I'll just pretend I didn't read that.

Anyway re the coax v. optical issue. Optical is good over long distances because:

1) the latency through fibre is lower

2) signal fade is less, so less repeaters are needed; again reducing latency

3) fibre has much higher bandwidth than coax

4) In the case of harsh environments, ie. as with undersea cables, optical signals remain unaffected by interference

Why coax > optical in domestic purposes:

Your CD player functions with circuit boards, which function on electrical pulses. With a coax, all the CDP does is to feed unaltered electrical signals straight into the coax out, while optical signals go through a converter, which sends light pulses based on time. The timing on the Tx and Rx ends of the optical path may not necessarily be in perfect sync so that's where you get jitter. Coax just doesn't suffer from this. RF/EM interference in a domestic environment with coax wouldn't be significant enough, just in case you didn't notice how heavily shielded coax cables usually are.

[dex Otaku]

Thanks, skyther.

BTW, I know people here who use their MDLP portables exclusively with LP2 [hardware encoded via optical copy] - because they like how it subtly alters the stereo image.

The first time someone told me that, I almost choked on my drink - but there it is.

[physya]

True, but the bitstream going over AES/EBU, SPDIF coax or optical does not contain this kind of error correction.  CD's error correction is part of reading the stream from the disc.  What comes out the digital pipe does not work the same way. 

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That's the point... and this is why the errors can be introduced into a digital stream if sender/receiver do not have error correction protocol. I just think that not everybody realizes how much cable traffic is used for this correction to keep "digital be digital".