CDP Lasers and Lenses

[RobbieGong]

Can anyone shed some technical light on what these are/do.

This is more in relation to how they affect the sound negatively, if they are not as they should be ie: dirty lens, dodgy laser etc.

If hand cream, grease or such liquid gets on the lens, can it affect the laser as well ?

Also, anyone ever had a cdp sound wonderful one day and then sound wrong when switched on the next day, out of the blue, no warning ?

[Made in 1968]

All i know is most modern lenses are crappy plastic ones.

[NRG]

The lens keeps the laser focused on to the cd surface, the reflection is detected when the beam crosses from a pit to a land and back. The Pits and Lands are etched in to the CD surface. The laser strength is important for the reflective strength of the beam, some are not enough to reliably read CDr media for instance. The lens needs to be clean otherwise the beam can’t be focused on to the surface to read the pit to land transition. It’s also worth noting there are no 1s or 0s on a CD, CD is not a magnetic recording medium. The pits and lands are a time based based representation of bits, the length determining how many and the transition for pit to land a change from 1 to 0. HTH a bit!

[Light Dependant Resistor]

Can anyone shed some technical light on what these are/do.

This is more in relation to how they affect the sound negatively, if they are not as they should be ie: dirty lens, dodgy laser etc.

If hand cream, grease or such liquid gets on the lens, can it affect the laser as well ?

Also, anyone ever had a cdp sound wonderful one day and then sound wrong when switched on the next day, out of the blue, no warning ?

The lens should be clean, for the laser to work properly. You can expect data drop out or inability to read a disc altogether with a lens that has material on it.
With digital unlike analog, the compact disc player uses many astonishing feats of engineering to ascertain and correct replay. Whilst this is sometimes
criticized from a analog perspective, the digital domain has sufficient scope to be entirely different with different rules ascertaining what is allowable as
correct, and what represents genuine data loss.

No to the second question, in my experience CDP's of the same brand and model are extremely consistent with replay and reproduction,

As example if you have more than one CDP see if you can know which one is replaying, as each have certain signature sounds to them.
A Marantz sounds different to a Sony I think Sony's have perhaps the best accuracy with music replay, but the stable platter Pioneer I use is equally alluring
so are the two players I use the most.

Perhaps it is equipment down stream of the CDP in your system that is causing inconsistency ?

[Macca]

Also, anyone ever had a cdp sound wonderful one day and then sound wrong when switched on the next day, out of the blue, no warning ?

If you are having that experience I'd look at other factors as it is 100% not the laser and almost certainly not a problem with the CD player.

What other factors are different? Curtains open or closed can have an audible effect (should be better sound with them closed). Are volume levels different? Are you comparing the same recording? Sober vs under the influence? Amplifier warmed up as opposed to just switched on? Big difference in the ambient temperature of the room between the two comparisons?

[struth]

If using the cd players own dac it could have capacitor issues.

[RobbieGong]

To add some context as I've been in this game a long time - system always switched on hours before any music is played - standard.

Although I've had my cdp for some years I only really got to listening to it properly recently, as reported here and it was a revelation in terms of how good cd can sound to my ears, as a vinyl addict.

For two weeks straight it sounded fab !

Then, I put a cd that had played perfectly fine before, one day and it skipped so i put another regular / familar cd in and sat down and became aware that the sound was wrong.

Sound is now pinched, closed with a level of distortion and just overall very poor.

I've cleaned the lens with a cotton bud type swab, dipped in isopropyl alcohol cleaner - no change to sound at all.

I'm baffled. Hoping it isnt the analogue / output section. It's a lovely rare thing, pretty much cosmetically near mint. I really dont want to lose it.

Btw - I've also done all the usual basic trouble shooting, ie: checked and reconnected interconnects etc, speaker channels and amp all good.

Unplugged, re-plugged - you name it.

If there's something on the lens, then cant imagine as I cleaned it. I'm baffled

[Macca]

If it's a 'scratchy' sort of distortion that's low laser power i.e laser is on its way out so the only fix would be a new laser that isn't a counterfeit one. I don't think there's much chance of finding an NOS one. It's harsh I know but nothing lasts forever. You might find another PD91 that has other issues but the laser is fine, and you could swap them over.

However the skipping is probably a separate issue. Have a read of this https://www.audiokarma.org/forums/in...layers.440522/

[RobbieGong]

Skipping isnt an issue as it only did that one time.

Wouldnt be surprised if it is the laser and as you say finding one will be pretty nigh on impossible. The part PWY1004 isnt available anywhere I've ever found and that's assuming that the issue is the laser.

As much as i love vintage gear, vintage cdp's are another example, that as good as some of this gear is, when working properly, reliability and parts are always gonna be an issue to some extent, as many have found out.

Worse, they just dont make them like the PD-91 anymore, great looks, sound and build to match, copper chassis, wooden sides etc etc.

If there's a modern equivalent I'd like to see it, and even if it does, the cost today

[Macca]

Get another vintage high-end player then. Still loads about. Yes it will go bad in time but what can you do? Just don't pay the silly money some people are asking for them. Three grand for a wooden-cheeked future boat anchor? I don't think so! There's also a lot of players that are off the radar but are equal or better to the old high-end stuff and can be had for under £200.