Have your say & ask the experts

Andrew Everard:

pwiles1968:

how much credence is there in the CD tweaking side of things that are also supposed to improve the reading of the disc, green pens, freezing the CD's etc

Can't speak for the effects of freezing, but the idea of the green pens was to reduce light scatter within the transparent layer of the disc, while other companies made green 'tyres' which fitted round the rim and had the extra claimed effect of increasing the mass a little, adding to the flywheel effect and thus stopping the discs from wobbling as much in the player.

Similar thinking was behind the TEAC VRDS system, with its disc-sized clamp, Pioneer's Stable Platter Mechanism – disc upside down on a turntable, read by the laser from above – and any number of aftermarket disc stabilisers.

Did any of them work.

chebby:

JohnDuncan:

So bit-perfect data ripped to hard discs is better than CDs?

Now don't start that one going again.

Get a naimuniti then you can compare directly between CD and streamed lossless via the same DAC (and even have the output levels matched I think.)

Hopefully Joel did not read this.('Naim'. 'lossless', 'streamed', and 'DAC' all in the same sentence!)

[Edit] Just checked the online manual. And there is a function called 'input trim' (section 4.3 page E9) which.. "Enables the relative level of each input to be adjusted so that each is of an approximately equal volume."

Ideal 'vehicle' for those CD vs Lossless blind tests

 

pwiles1968:

Easy reading
So if you can make a disc easier to read, the error correction has less work to do, and the result should be a better sound, right?

Early CD player laser mechanisms and electronics had some really useful access points to their processing.

In the 80's I modified a Philips CD104 to output the amount of times error correction was being applied to the data stream. It also showed the quality of the signal being retrieved from the disc, along with amplitude, focus and tracking errors.

If I remember correctly the worst reading came from a copy of 'No Jacket Required' by Phil Collins with a total of over 250 = about 5 a minute. Would that really degrade the sound that much? After all it was not a continuous process.

I still have the player, maybe I should hook up the modification again; to see what the quality of recent pressings are like.

pwiles19:

Did any of them work.

Never too sold on green pens and rings, and of course not possible to compare the TEAC and Pioneer players with the same electronics fed from conventional mechs, but yes - the VRDS and SPM players sounded very good indeed.

Andrew Everard:

idc:

I asked this on the blog, but no harm in asking again, Andrew, will you have a try at importing one of the CDs onto itunes and make a comparison? Please.

Already tried that, idc, and there's no obvious difference in the sound between standard and 'new-spec' CDs.

Of course, because the rip is able to use more error-correction, and isn't happening in real-time (as the data-extraction is when simply playing a disc), that's exactly as you would expect it to be.

Thanks Andrew.

JohnDuncan:

Discussed here

Interesting reading - suggesting that the manufacture of a CD can turn modest spinners into better ones. Thoughts?

Interesting, although I doubt that anyone  can really hear the odd missing bit. It has to start skipping before it's noticeable.

Ah, the old 'bits is bits and all CD players sound the same' standpoint.

Next you'll be telling us that mains cables don't make a difference, there is no god, homeopathic remedies don't work and Fred Scuttle wasn't real.

Andrew Everard:

Ah, the old 'bits is bits and all CD players sound the same' standpoint.

Next you'll be telling us that mains cables don't make a difference, there is no god, homeopathic remedies don't work and Fred Scuttle wasn't real.

Doesn't follow because all CD players don't sound the same. Fred Scuttle? Wasn't he a Benny Hill character?

Yes a bitstream is a bitstream, but the bits being read can also be seen as a radio frequency signal (11Mhz I think) and there are factors that affect this RF 'signal' in real-time (when viewed as an 'eye pattern' on an oscilloscope) that are not as simple as just conveying a linear stream of bits. Scattering and spurious reflections and even breakthrough of acoustic/mechanical vibration can all affect this 'analogue RF' component of the transmission of the digital bits from the laser pickup and result in jitter.

So care taken by a CD player manufacturer in the suspension, mechanical isolation, and even judicious use of expensive (near IR) light absorbent paint in the right places in the transport can reduce 'interference' to this radio frequency transmission of bits.

Although DACs used in CD players are fairly democratic (and cheap), the quality of components and design in the analogue output stages of a CDP can make a huge difference.

JohnDuncan:

Discussed here Interesting reading - suggesting that the manufacture of a CD can turn modest spinners into better ones. Thoughts?

CD's can sound good, XRCD (plays on any CD player), unfortunatley not much of a mainstream catalogue, but they sound great. it's amazing what can be done with the plain old CD if it's mastered and produced properly.

regarding the errors that a CD player could produce when playing a disk - In photography theres a techneque called stacking (I think). The idea is that you can take more that one image of the same view (say 10 images) then the program stacks them, avaraging out any visual noise, and adding dynamic range to the shadpws, it does this by taking the best of every image to produce a super clean image.

Anyway, I could be wrong, but could something similar be done with ripping a cd ----- rip it 10 times and assuming all the errors arnt in the same place, get a program to clean it up correctly?

mushroomgod:

regarding the errors that a CD player could produce when playing a disk - In photography theres a techneque called stacking (I think). The idea is that you can take more that one image of the same view (say 10 images) then the program stacks them, avaraging out any visual noise, and adding dynamic range to the shadpws, it does this by taking the best of every image to produce a super clean image.

 

Anyway, I could be wrong, but could something similar be done with ripping a cd ----- rip it 10 times and assuming all the errors arnt in the same place, get a program to clean it up correctly?

 

This would not generally be necessary, most CD mechanisms, including the cheap PC CD re-writers, are able to produce an error free stream from a pristine CD; even at up to 52X CLV read speed. It is possible to do 10 rips and do a bit for bit comparison and they will all be exactly the same!

Stumpy21:

mushroomgod:

regarding the errors that a CD player could produce when playing a disk - In photography theres a techneque called stacking (I think). The idea is that you can take more that one image of the same view (say 10 images) then the program stacks them, avaraging out any visual noise, and adding dynamic range to the shadpws, it does this by taking the best of every image to produce a super clean image.

 

Anyway, I could be wrong, but could something similar be done with ripping a cd ----- rip it 10 times and assuming all the errors arnt in the same place, get a program to clean it up correctly?

 

This would not generally be necessary, most CD mechanisms, including the cheap PC CD re-writers, are able to produce an error free stream from a pristine CD; even at up to 52X CLV read speed. It is possible to do 10 rips and do a bit for bit comparison and they will all be exactly the same!

so are you saying that there is no difference in total errors between a CD player and a PC rip? or have I got the speeds mixed up?