the definative cd lathe test

Some good and interesting points made both for and against ....

As I've said before ...ad nausium

ripping a disc that has been lathed and the original has no effect ...for me they both sound the same

the only reason I can think of is that the effect is transport mech sensitive ie cdrom drives and the like don't seem to be effected ....I repeat I don't know why so don't ask me !

therefore its logical to assume if a cdrom drive is used in the ripping ...the effect is imo likely to be minimal.

Rob ..thanks for the quick turn round on the disc ..they beat me back from my hols .

I use an external dac for my 99cdp2 ...the effect is clear ...

this raises another thought .....

some cd players may not be effected in the same way ? [as previously suggested] so

lets assume the original hypothosis is correct ..that the cut reduced reflected ir back to the laser ..as the makers state

some mechanisms may be more susceptible to the reflected /stray ir within the player ...... on the past I've built a green screen round the mech of a denon cdp [dcd960?] with a very slight improvment in sound quality....

that said I've tried stabilizers and the stat mat ...with no effect

Another thought ....

my wife finds it very hard to hear these changes ....

she says she listens to the whole of the music ..often not even hearing the words in songs let alone ..say the air and space round instruments. Could it be that some people don't listen in the same way as others and therefore miss some of the spatial clues ?

This applies to cables too ......



I've most of the disc now returned so anyone wanting to listen to identical disc please contact me ..... I'll pay the outward postage ...can't say fairer than that !

 

concentricness of cd's .......

As you lathe the disc with the playing surface upper ...its very clear that a great number of disc the centre hole does not correspond with the projected data centre as yu can see the silvered play area oscilate back and forth ....

I've not got [to my knowledge two disc with off set foils ....I have lathed disc that have been off set ...

as davef has said not all disc have the same magnitude of effect ...so that throws another variable into the mix

I've lathed in the region of 500 plus disc's [not all my own!] in that time only two or three have had what I'd call no effect ....I'll see if I can remember what they are

which might be quite revealing ...


I sent a set of disc to a non hifi friend who has a half decent system ...[sony?] his group of friends were able to pick disc b the lathed disc everytime [so I'm told by his girl friends mother!].......they were just told to listen to the same tracks on the two discs ...[no mention of what was done to the discs]

I think the most important question is why are some hearing this and some not ......rather than is there an effect ..[if there was no effect people with zero interest in lathed disc/hifi ie a control group should not experience the effect if the effect was not present ......this is anecdotal only

 

Lots of interesting points Pete.

I would only add that the discs weren't ripped in the usual was using a rom drive. They were played real time on a dedicated CD transport.

The only area I can see that might need further research is the possible effect of servo activity on a shared PSU if the standard disc is off-centre.
I can't see how anything would be audible using a separate dac though as there is no coupling, especially via optical.

Certainly in this case I think we can eliminate the transport as both discs gave bit perfect output and null.
So potentially with integrated machines there might be some effect, depending on the power supply arrangement, but it needs further investigation before I'd be convinced.