Where is the magic in a SHM disk?

So people in this thread are really admitting that their expensive CD players are worse than any $5 cd-rom drive... weird.

 

As suggested above, you should read up on how analog is converted to digital and vice versa. "Correcting errors" is done all the time. It is not turned on and off. The key word here is "correcting". A CD has to be extremely screwed up to have this correction fail and if it does, one or two (or even 1,000) bits being wrong simply cannot make the analog output sound completely different.

In order to "color" the sound, you'd have to change ~475,000,000 1's and 0's (for a 45 minute CD), not just a few of them.

 

1) Correcting digital errors does not "normalise" the sound.

2) You should realise that the vast majority of CDs are read without any error correction being applied. Error correction is really not an element in the sound of CDs as there is no error correction unless the disc is badly scratched.
Repeating that normal CDs sound different because they contain more errors that go uncorrected is factually wrong.

I still stand by my suggestion that you should understand how digital signal processing works before you delve into the SHM marketing material. Any student trying to read a university dissertation based on that material would be sent home within five minutes. It's so unscientific that personally I think that any company publishing that material should be sued for the way they misleading customers.

 

No, but I have heard coughs, claps, shouts, chatter, sweet packets, and plenty of other stuff

Tim

 

If that was to happen, the entire field of audio would be cringing...

 

Stop making sense! In some ways, its more fun to "believe" that something has a nice effect ( whether it can or cant ) than to hear the hard cold sterile reality.

Maybe SHM is better, mabye not, but as long as some "Feel" or "think" they hear a more pleasant sound, isnt that the goal?

More enjoyable in the end, not listening to scientific theories of why it cant be better!!

 

What I hear through my speakers is not unscientific. SHM does what it claims, although at a detriment to the music, in my opinion. The material works as stated. No need for a lawsuit.

 

Do they supply the Super-High-Material when they ship the CD? Is it supplied in resin or in unprocessed plant form?

 

Lets get some music in this thread .....

 

To be clear, the error correction logic is always running. And it is possible that *correctable* errors are not uncommon (that is to say, errors where the original digital data can still be constructed, with no errors or differences on output). You are correct, however, that *uncorrectable* errors are rare (where the data is either interpolated or not retrieved at all).

It may or may not be, depending on the conditions under which you listen, but your analysis of what is causing (maybe) differences is most certainly unscientific.

 

I wouldn't say worse, but I also wouldn't say better - at least with regards to the ability to read binary data. In fact, most CD players contain transports from the same handful of manufacturers such as matsushita, etc.

CD players, though, do offer much more than a $5 CD rom drives: A remote, a power supply, a ~17 inch wide enclosure which fits in a typical cabinet, various types of outputs such as balanced and unbalanced analog output, optical and coax digital, etc. Also, the last time that I used analog output from a CDRom drive (circa 1996), it was incredibly noisy unlike a typical CD player's analog output.

 

No, but some are saying that there is a fundamental difference between playback from an optical disc and playback from computer memory, and that difference can change the sound.

An optical storage system is a very complex electro-mechanical device, and it's very difficult to construct an inexpensive commercial system for real-time playback that can preserve timing and data relationships to the degree that some now feel is required for no sonic degradation (at least in a highly refined sound system with discerning listeners). The waveform recovered from the CD by the laser head is very similar to an RF signal with nine superimposed sine waves that must be converted to a digital data stream for loading into a buffer that allows a feedback loop to be setup for controlling disc speed, and hence maintain a constant data rate. The trouble is that the shape and precision of the pits (or more precisely, the lands) on the disc, and how well the laser is able to focus on the edges will determine to a certain degree the amount of timing irregularities (jitter) that is on this analog signal before being buffered. The clock driving the buffer output allows most of the timing irregularities to be removed, but the transitions on this incoming data stream will also influence the timing accuracy of the system clock thorough a variety of mechanisms, including power supply impedance, ground system, circuit trace impedance and even RF radiation.

So improving the timing stability in the clock used to write the data to the disc when the master is made, or improving the manufacturing process to generate better defined lands on the disc, or even applying polish and/or other treatments to the disc surface in order to help the laser better focus on the land edges on the disc could conceivably lead to improved sound with no change in the actual data presented to the D/A convertor because of less jitter transferred to the conversion clock. The right data at the wrong time can create very non-musical distortion components, especially at low levels since it is not linearly related to the signal amplitude, but can be related (correlated) to the digital word data pattern.

 

Just for yucks, I'm ready to bite the bullet, spend 150% to 200% as much as I typically would on an album, and test for myself. Can anyone recommend a good album that best demonstrates the advantages of the material? (Or, as Holy Diver might suggest, one which demonstrates the disadvantages of the material.) I like all types of music, but in order to conduct the test that I've outlined above, it must be a redbook CD or at least contain a redbook layer. I'm open to any suggestions that meet those simple qualifications, except that I will NOT be purchasing the Carpenters 40th anniversary SHM-CD set from Amazon at us $780.

 

All SHM-CD discs are redbook. SHM-CD is not a different format (ie. SHM-SACD)...they are playable on any CD player.

 

I ripped my SHM copy of Joe Jacksons Night And Day to a blank conventional CD and compared it to the SHM that I ripped it from. Absolutely no difference in both. I then compared the SHM to my 1983 AM+ CD. Huge difference.
All thats left for me to say is ........

 

Not saying YOU don't hear a difference but if it can't be proven and documented and therefore peer reviewed then it's not scientific. Sorry.

 

Right. In order to conduct my experiment, I am looking for a recommendation which is not a single layer/non-hybrid SHM-SACD. Although it appears that carrolls already conducted my experiment as noted in post #240.

 

Of these three SHM-CDs I have read in this forum that they are supposedly the best digital version (I don't have them myself), so they might be worth buying anyway:

Buffalo Springfield: "Buffalo Springfield Again“
Neil Young: “Harvest”, “After the Gold Rush”

 

opcorn:

 

I guess any kind of testing the possible advantages of the SHM-CD can only be done by comparing a CD and an SHM-CD that have identical files (mastering) on them, otherwise you won't be able to tell if you are just listening to a very well mastered album and attribute the good sound to the material.

 

Right. That's what I intend to do (and what carrolls did with his Joe Jackson shm-cd): Extract the data from the SHM disc to a computer, burn the resulting data to a CD-R (which contains dye and is definitely not SHM), and then A-Bing the two discs.

I admit that I'm going into this from a very skeptical point of view. I'll point out that I would expect the SHM disc to outlive the CD-R by many years, but but for now I would expect it to contain the same data.

I'll use my ears and my admittedly low-fi equipment to be as objective as possible, but my hypothesis is that the following will also be true:

SHMCD -> EAC

will be equal to

SHM CD -> EAC -> CD-R -> EAC

 

That might only show that a pressed CD sounds better than a burned one.

 

You have to A/B the regular CD and the SHM CD themselves that have the same mastering. Not ripping or burning anything. The SHM will sound different due to the material it is made from. That simple, at least for the CDs I have that contain the same mastering but are one of each. I can tell which one I like from the two.

 

Will? Or might?

 

13 pages on and I'm amazed this thread is still active.

I happen to know a thing or two about what's inside your CD player and your CDs*, so I'll share my opinion.

For any two bit-identical discs, the stream of 0's and 1's that are read off the disc are ALWAYS THE SAME. The theories that are batted about about error correction, lasers, pit shape and non-transparency of the polycarbonate are all crap. Sorry, that's not how digital works.

An analogy: You can wear whatever sunglasses you want, but if you can make out the words in this post, then the letters will always be the same. (If your glasses are too dark and you can't make out the words in the post, then it's just noise - that's what you hear when the CD is really, really damaged. You know it when you hear it; this is not the noise we're discussing here in this thread.)

If two bit-identical discs sound different to you, then it's the fault of your CD player. And it's not the fault of the stream of 0's and 1's that are read off the disc, or the built-in error correction that ensures that those 0's and 1's are accurate. It's the effect of the other electrical stuff in the player that's all running off the same power supply.

Example: If a disc has a tremendous wobble at 35 Hz, the focus and tracking servos may see a lot of activity at 35 Hz. If those focus and tracking servos are tied into the same power supply that amplifies the stream of 0's and 1's, then it's possible that some of that 35 Hz activity may bleed into the ANALOG signal that's sent to your speakers. The 35 Hz isn't in the DIGITAL signal; it's only in the ANALOG signal due to a small amount of bleed-through in the analog electronics. That's why people spend thousands of dollars on fancy power supplies - to cut down on the type of electrical interference between circuits that can cause (admittedly minor, but audible) deterioration of the sound.

If your CD player electronics were perfect, there would be no such bleed-through, and you wouldn't hear any difference between bit-identical discs.

That's also why if you rip bit-identical discs to your hard drive, they sound the same. No more electrical interference from other circuitry inside your CD player.

The main claim of SHM, namely that the difference in substrate transparency affects the sound, is COMPLETE crap.

Polycarbonate is extremely transparent at 780 nm; it's on par with any common optical glass at that wavelength. The laser has to travel through a total of 2.4 mm of polycarbonate (1.2 mm in each direction, assuming normal incidence), and the drop in intensity associated with transmission through 2.4 mm of polycarbonate is ridiculously small. (You can still read signs through your car windshield, can't you?) Nearly all of the drop in intensity is caused by reflections off the front surface of the disc, which amount to about 4-5% of the light in each direction. Losses from those reflections, as well as the other optical effects, are built into the optical specs for the CD head.

The bottom line: if you hear differences between bit-identical discs, it's the fault of your CD player. You're hearing noise in the ANALOG output signal that's caused by other stuff that's fed by the same power circuitry inside the CD player. It's NOT that the streams of 0's and 1's are different; the DIGITAL signals in the player are the same.

* A handy link. I think I know what I'm talking about.