CD stoplight - some analysis

OK, have just sacrificed Philippe Herreweghe to the interests of science and attacked him with a large indelible black marker. Result - no difference that I could hear. I remain more than ever an unbeliever.

 

You know this I'm sure, but there is a distinction between something that looks black and something truly black (a black body). If you look at something you are by definition only seeing how it behaves in the visible part of the spectrum. To take a very extreme example I could look at a black wall but know perfectly well that a radio wave would pass straight though it. In the current case, the wavelengths we're talking about are sufficiently close to visible that I reckon you're right that black ink would absorb just as well, but I'm willing to concede that this might not be the case.

 

Tones,

if I were you I wouldnt bother any more with these kinds of tweaks. I would have thought that past experiences would have put you off by now

 

But can it be noisier? After all, the thing only reads, can only read, a one or a zero. There can never be a 1.15 or a 0.15. The word "noise" in this context would therefore appear to have no meaning, unless there was major disruption, so great that the error correction systems that correct the (inevitable) errors on the disc were overcome. And if that were the case, would it not happen anyway, and why should marking the edges of the CD make any difference?

 

The only sacrifice made of course is that if you pull that CD out to play when other people are around you'll have to explain why the edges are black .

 

I'm fast arriving at that point, Robbo!

 

That's why I sacrificed it - it was a free demo disc that never gets played and is only useful as a coaster or for things like this.

 

If the Stoplight pen reduces jitter then presumably this can be measured? Surely someone like Paul Miller at Hi-Fi Choice could do/has done this?

 

Well, I was thinking of two possible things. Firstly time domain jitter, i.e. I could see how stray light will affect the 'shape' of the light pulse reaching the detector, but could this cause any timing errors? Secondly, there has been talk before of electrical noise traveling along digital interconnects, superposed on the digital signal, having a detrimental affect on the DACs performance. Now I don't imagine that there is a direct conversion of say light signal to electrical output that might give something like this, but if there was... That's why I asked about the light - digital signal conversion of which, as will be obvious to those cringing reading my preceding words, I know bugger all.

 

Robbo,

I don't have a fascination for bake-offs – you may have used the wrong word there. However, I do have a fascination for the music, the whole music and nothing but the music. But somehow, I get the feeling that for many of you, the fascination lies with boxes and measurements but not with the music or using your ears. Am I getting warm?

The bake-off or myth-busting day (as the bake-off is now creatively being called) is the perfect opportunity to prove or disprove a lot of the theories that are now spilling out over the many pages on this thread. Yet all we seem to read about in the bake-off reports is how much 'thwack' such and such a person's system has or how wonderful His Lordship's system sounds etc, etc. Well there is more but I'm sure you got the drift. Is that why the name was changed to 'Myth-Busting Day'? Another observation is that people seem to prefer debating on forums, the effects on non-effects of certain products when there is the perfect opportunity at these Myth-Busting Days to do what it says on the outside of the box, (and I hate to say it) bust a few myths. Therefore, if this means that I have a fascination (your phrase) for bake-offs then so be it but every bake-off report appears to read like the last one whilst all tests are carried out by written debate on the forum.

Btw, are a lot of the posters on this thread in the science or technological professions because if you are, it could help explain the 'fascination' for measurements (occupational hazard, I guess) over using your ears and enjoying the music. A lot of high-end audio equipment designers also share this view in that listening with their ears to their creations is not as important as how it measures in the lab so you are not alone. Just a thought and on that note .............



Enjoy the music,

Lawrie.

 

It is entirely possible to do both .

For my part I'm very interested in getting to the bottom of some of these issues as I have tried a number of so called tweaks, some of which from my listening tests I'd say worked, and therefore use. The arguments put forward by those more knowlegeable than myself that such effects are phyiscally impossible, and that perceived improvements are psycho-acoustic in origin, is at least one I'm prepared to entertain. (Oh, and I am guilty of being a physicist, but I can assure you I don't by HiFi on technical specs !).

 

Jitter

Well acording to a post by Stewart Pinkerton in Google (he's the guy who will give you £1000 for passing a cable double blind test), "The green pen can ONLY affect the accuracy of data
recovery, which is already virtually perfect (error rates of less than
oone in ten million being standard). Jitter is a separate issue which has nothing to do with the optical reader (where jitter levels are in fact horrendous, but are COMPLETELY removed - but perhaps replaced by new jitter from the master clock - at the output of the RAM buffer which is an esssential part of EVERY CD player)"

http://groups.google.com/[email protected]&output=gplain

Also note that Mr Pinkerton refers to the green pen thing as starting as a newsgroup joke: "this was a joke by one of our older contributors more than a decade ago, which got out of hand and into the market place. Never underestimate the paranoia (or gullibility) of the average audiophile!"

http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&[email protected]

 

Blimey
I sit down for a sunday lunch and 30 posts hit the system...

 

Not really, no. I think most of us who attend bake offs share your love of hearing new music. Thats probably why nobody is really bothered about conducting properly organised tests. They'd rather listen to music and have a good chat. I personally prefer the get togethers where no equipment is swapped and we just chat and listen to music (There have been many of these, they just dont get discussed on the forum).

 

Just a thought, Teac have recently launched the no holds barred Esoteric CD mechanism. I wonder why they felt the need to coat the outside of the VRDS mechanism in green paint? Surely multinational electronics companies dont just do these kinds of things for the fun of it as it must have significantly increased manufacturing costs. There must be a technological/sound quality reason behind it.

 

I've seen several of these hi-fi green pens back in the early 90's. All they are are the glass pens that pubs use to write out their menus. If you pay more than £2 for one from any reasonable stationary shop then they've seen you coming.

Thats the thing with 'specialised hi-fi improvent tweaks' often you will find the same product for sale in its proper intended marketplace for significantly less. Very few specialised 'hi-fi' companies produce/develop items at great cost that will potentially only sell in very small numbers. There is a lot of re-badging in this business. Be careful out there!

 

The cynic in me says, "So that audiophiles will pay an arm and a leg for it". It doesn't take much to paint a mechanism green if it can be used to justify charging vast amounts of moolah for it.

Having said that, it may work for all I know. Never actually tried painting any of my CDs. Or transports.

-- Ian

 

Presumably for the same reason Chord felt the need to launch an enormously expensive transport to match the DAC64, having previously announced that they'd designed the DAC64 to be transport-independent

 

Cynics, the lot of you


IMO, the DAC64 never was transport independant, but thats a subject for another thread

 

Oh, sorry. Of course.