Weight on CD ?!?

[datune]

Today a service guy came to where I work to place the hands free car kit (Parrot stuff), and whilst he was installing we started talking about audio and acoustics (seeing how the company were the guy works also does audio installations etc...).

Pretty soon we started arguing about whether or not super high quality cable (read -> 0.75cm cable that costs 2500 dollar vs a cable that costs 40 dollars) actually makes an audible difference.

I actually am convinced that it doesn't make a difference, and he said he used to think the same, until he was invited over by one his clients, who had a high fidelity audio installation worth over 145.000 dollars (which apparently consisted of nothing else then one amplifier, one DA converter, one CD player and two speakers, that's it).

That client challenged him to do a test of whether or not he would hear a difference, but he always knew whether he listened to the cheap cable or the expensive cable (which I quickly pointed out pretty much made the test useless cause obviously you may be dealing with the placebo effect etc...).

Nonetheless, the technician pointed out that the difference was quite big, and VERY noticable that it sounded different.

But it get's A LOT better. And here's where I hope Bob Katz will jump in. He then told me that the client did another experiment with him.

The CD player: When you put the CD in the tray, you had to click it, and then you could add a WEIGHT on top of the CD (???!!!!???), which the client claimed would lessen possible reading errors (which he also claimed he could hear).

The technician said to his client:" Are you mocking me? That's impossible".
They then proceeded to execute the test, and sure enough the technician said to me he could hear a difference.

Now I would like to know, is this at all possible?

Summary:

1. hearing differences in cable brands, is it possible?

2. CD player which allows to add a weight on top of the CD, lessens reading errors during loud volumes? Does this really exist?

[Darius van H]

I know this will come as a controversial and perhaps shocking suggestion, but is it possible that they imagined they heard a difference?

I love these kind of anedotes......it's never the case that there was "maybe a difference but i was not sure and i could have been imagining it", it's always a "BIG" difference!

I would also say his CD player seems to be underperforming considering that it cost (presumably) a large chunk of that 145k, because my 60 euro Plextor burner will rip an audio CD (without any weights or crystals added) to a good enough degree that it will cancel bit for bit with the original wav file from which it was burned (although i do admit to having a dream-catcher draped over the power-cord).

edit: i just re-read your original post, and it seems the weight is part of the design of the player (like some of those fancy Sony SACD players), in which case it could make a difference as it's designed to work that way, although i imagine it's more likely designed like that for theatrical effect!

[Lagerfeldt]

1. hearing differences in cable brands, is it possible?

Yes, but mainly if you're testing very different types of cables. I personally can't hear the difference between my $100 Oehlbach and my $400 Oehlbach cables at home. So guess which type I didn't buy more of. For my studio I use Mogami with Neutrik all around.

2. CD player which allows to add a weight on top of the CD, lessens reading errors during loud volumes? Does this really exist?

Yes, I have one in my CD player in the studio. It stabilizes the cd while rotating which in theory could lead to less read errors under some circumstances. Read errors results in the CD player error correction interpolating the audio which degrades playback, even if it's just for a fraction of a second. It doesn't have anything to do with "loud volumes" though. As Darius says, this is part of the design with many Sony players. And a pain in the ass.

You can't simply rip an audio cd into your computer and compare it to a WAV file in your DAW by flipping the polarity, and because it nulls claim it actually is identical in the "real world". While it absolutely is identical inside the DAW, it might not be when played back on a CD player. While this sound like a bit of a paradox it's due to physics in the burned cd as the pits might be unevenly spaced or rounded which causes the player to error. But the ripped version isn't necessarily ripped in real time or the CD drive used for ripping might read the cd better. This is why the same cd can sound different on two different CD players, not considering D/A, etc.

In most cases all this is purely theory. But as this is Gearslutz AND the mastering forum, I think going into details is alright :-)

[807Recordings]

Originally Posted by Lagerfeldt

Yes, but mainly if you're testing very different types of cables. I personally can't hear the difference between my $100 Oehlbach and my $400 Oehlbach cables at home. So guess which type I didn't buy more of. For my studio I use Mogami with Neutrik all around.


Yes, I have one in my CD player in the studio. It stabilizes the cd while rotating which in theory could lead to less read errors under some circumstances. Read errors results in the CD player error correction interpolating the audio which degrades playback, even if it's just for a fraction of a second. It doesn't have anything to do with "loud volumes" though. As Darius says, this is part of the design with many Sony players. And a pain in the ass.

You can't simply rip an audio cd into your computer and compare it to a WAV file in your DAW by flipping the polarity, and because it nulls claim it actually is identical in the "real world". While it absolutely is identical inside the DAW, it might not be when played back on a CD player. While this sound like a bit of a paradox it's due to physics in the burned cd as the pits might be unevenly spaced or rounded which causes the player to error. But the ripped version isn't necessarily ripped in real time or the CD drive used for ripping might read the cd better. This is why the same cd can sound different on two different CD players, not considering D/A, etc.

In most cases all this is purely theory. But as this is Gearslutz AND the mastering forum, I think going into details is alright :-)

like the Teac VRDS Transport?
It has been tested to have lower jitter than other cheaper brand ones and part of their claim is because of the weighted disk that couples to the CD or DVD etc. It is in many very high-end brands but I suspect good design is really the factor and not the weight.

[Lagerfeldt]

Agreed.

[Darius van H]

Theory is fine, but that still doesn't explain why you'd pay thousands of euro's for a CD player that plays CD's less accurately then a 60 euro DVD burner.

[Lagerfeldt]

Haha, you got me! I don't think my CD player cost more than €850 though.

But seriously though, you can't compare like that unless you rip in realtime. Not relying on realtime means you can take all the time to re-read in case of errors when ripping.

In realtime playback on a CD player you might have cross interleaved coding but you don't have infinite time, hence the need for on the fly error correction.

A nice feature on my CD player is 3 filter settings on the D/A, off sounds very "Japanese" i.e. high freq happy, while 1 and 2 are gradually more filtered. 1 sounds best to my ears, a good compromise. But I always test with 0 (off).

[UnderTow]

It sounds like someone should have spent 145.050 $ on their set up and gotten a CD player with a proper transport. ;)

As for the cable thing: The guy could earn back his investment 6 fold:
Calling Bullshit: James Randi Offers $1 Million If Audiophiles Can Prove $7250 Speaker Cables Are Better

Does anyone truly believe that NO ONE would claim this prize if they could really tell the difference? Occam's razor.

Alistair

[Boomshanka]

Originally Posted by Lagerfeldt

A nice feature on my CD player is 3 filter settings on the D/A, off sounds very "Japanese" i.e. high freq happy, while 1 and 2 are gradually more filtered. 1 sounds best to my ears, a good compromise. But I always test with 0 (off).

Sounds like you've got something like the Sony CDP X3000 which we have here, with the filters "STD" or 1, 2, 3 (though we use the digital out) and the centre weight (which of course is not for enhanced sound but purely for stabilizing playback - this machine's design).

[credentialed]

Originally Posted by Lagerfeldt

Yes, I have one in my CD player in the studio. It stabilizes the cd while rotating which in theory could lead to less read errors under some circumstances. Read errors results in the CD player error correction interpolating the audio which degrades playback, even if it's just for a fraction of a second. It doesn't have anything to do with "loud volumes" though. As Darius says, this is part of the design with many Sony players. And a pain in the ass.
)

Reminds me of the days of growing up with vinyl. When our records would get scratched we'd put a penny or two on the end of the arm to hold the needle down so the record wouldn't skip.

[Bob Olhsson]

It's more likely that people are hearing a minute speed change caused by the motor servo heating up the crystal than anything to do with data errors.

[datune]

First, thanks everybody for the replies.

Second, right after posting, I started researching and searching across this forum, and I now realize that the cable issue seems to be a very delicate one, to say the least. I have formed my own oppinion by now, but to avoid flamewars, I'll just keep quiet about the matter.


I really didn't know about those kind of CD players, and I agree with what some in this thread suggested, imagination can go a long way

[Francis Vaughan]

This stuff has a loooong history in the audiophool arena. There are good and real technical reasons why differences can be heard, but what does not follow is that if your gear produces these differences, and you can induce them, that you have a technically good system. Quite the reverse.

One point, this was made in a recent thread here, there is no interpolation occurring during error correction - the errors are completely corrected - which is why the DAW null test works. Very very occasionally a CD player will encounter an uncorrectable error - typically a few in an entire CD, so they are many minutes apart. These do get interpolated (typically) by the DAC. The S/PDIF subcodes flag the packet as bad.

What one did see in the loony end of audiophool components were broken designs. There is no shortage of insanely expensive digital components that have been incompetently designed. Often designers with some experience in analog electronics who think they can simply bolt on some digital bits. Such devices can have much greater sensitivity to jitter on the input than more mundane, but competently designed gear. Yet the fact that the DAC is so sensitive to jitter on the input is held up as a good thing - the DAC is so good that it can "resolve" the nuances of different sources and even the sort of cable used. Which is silly, at best.

And the cable? Sure. Cables can have a huge effect on jitter. If the gear they connect is badly designed. Poor termination is a good start. Poor noise rejection is another. Simply terminating into a resistor and a Schmidt trigger is guaranteed to give trouble, because most logic gates are not designed as line receivers and actually spit back energy when they transit levels.

Counter intuitively, a more lossy cable can be better, because it attenuates the energy ringing in the cable, and tends to open up the "eye pattern" seen at the receiver. Thus yielding lower jitter. Indeed, one of the mantras of good design is to have as wide a bandwidth as needed, but no more. Ultra fast logic causes more problems than it cures. Low jitter requires controlled rise times and a clear understanding of other aspects of digital design that are not found in undergraduate level textbooks.

So, I'm not at all surprised that differences can be heard. What one can't do is infer that this is due to some fantastic level of quality of the system. It is more likely to be the result of a very good backend (amp, speakers) revealing design flaws in the digital components. Flaws that can be exacerbated by messing with things like cable loss and cable length.

Swap out the DAC for a competently designed one (the usual offenders, Benchmark, Lavry, etc) and the effect goes away. Yet the audiophool complains that sound has lost a certain something. An inability to justly the insane cables being one of them. I'm also convinced that the final design tuning that occurs with these silly priced DACs partly involves tweaking to find a sweet spot where the distortion effects of jitter induced from the S/PDIF input (signal correlated) are fiddled to a point where they add a euphonic colour to the sound. This may involve simple blind fiddling with grounding and bypassing, with no understanding of why it is changing the sound, but simply providing a way of tuning it. The designer then trumpets the importance of designing by ear, and hints at mastery of deep and subtle arts, when in fact no such thing is true at all.

[Ethan Winer]

Originally Posted by datune

imagination can go a long way

Yes, imagination, and placebo effect, and also comb filtering as described here:

A common-sense explanation of audiophile beliefs

--Ethan

[Professor]

I believe that in the world of digital 1's and 0's it makes absolutely no difference if you use a £20 cheap computer CD drive vs a multi £thousand high end cd player to READ the information - the only important part of playback is the DAC. To say that the DAC is sensitive to input errors is true to some extent, but look at the Benchmark DAC-1. It removes all the jitter from a bad source.

Thank about it. Every application on my PC requires bit-perfect execution, if there was even a small error then the program would crash spectacularly.

In actual fact hard drives and CD drives do produce a number of errors when reading, but these are corrected well within execution tolerance

We have Reed-Solomon error correction which restores the information exactly, read errors or not - they are corrected back to the original information precisely.

Reducing the read errors, makes no difference to the end product if the end product is identical regardless of being reproduced from lots of errors, or no errors.

Anyway check this out (taken from wiki)

"There has been a move by the recording industry to make audio CDs (CDDAs, Red Book CDs) unplayable on computer CD-ROM drives, to prevent the copying of music. This is done by intentionally introducing errors onto the disc that the embedded circuits on most stand-alone audio players can automatically compensate for, but which may confuse CD-ROM drives."

Deliberate errors!

As for cables.. I have NEVER heard a difference and I get bored just thinking about constructing an argument based on my experiences.

[producerwillj]

Off course there are differences in audio-quality from different brands of cables. But to say if one is better comparing to another is a matter of personal opinion.......

Holla
Will