Cleaning CDP laser lenses

Discussion in 'Solid State' started by rudedogg, Jul 16, 2014.

  1. rudedogg

    rudedogg AK Member Subscriber

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    Ok, i hope this does not sound crazy, or start a wild debate, but i cleaned the laser pickup in my Denon DCD-1500 . I SWEAR it improved sound quality, mostly the high end....sound nuts?? I will do this more often and on my other players from now on.
    The Denon was skipping randomly on all cds...sometimes more than others, and was becoming more sensitive to floor vibrations, i popped the top, cleaned everything up real good, and all seems well. I can now literally jump up and down next to my audio rack and very rarely cause a stir. I was ready to pull it out of rotation! Simple maintenence fixed 'er right up!
    Does anybody else do this?
     
  2. steerpike2

    steerpike2 Super Member

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    Yes, it maks sense. A dirty lens will cause read errors, maybe no so bad as to cause obvious clicks or gaps, but it makes the error correction and error concealment process work harder. Enough 'concealed' errors can become audible as a kind of edginess to the sound.

    Any of my many players that seems to sound less clean, or becomes abnormallly sensitive to certain discs, a lens clean is the firsts thing to be done.
     
  3. Binkman

    Binkman Addicted Member

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    Denon shared the same model cd deck hardware with (can't frigging remember the mfg.. in their boxes. Good reliable japanese mfr. went into a few top brands.)

    Many people people just don't realize the sensitivity of cd players thinking they are built like tanks and don't take care of them or just place them anywhere exposed to vibration. I'd be leery of getting a used one shipped to me as some gorilla on shipping dock will ruin your day if not packed and labeled "Fragile".

    (movie: "Xmas story".. "fragiliee... must be italian" when he got his leg lamp)
     
  4. cademan

    cademan Addicted Member

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    Q-tip and rubbing alcohol!

    EDIT: Only if the lens is glass! I had no idea they made a cheap plastic lens. All of my CD players (all 8 of them) use a glass lens.
     
    Last edited: Jul 16, 2014
  5. slow_jazz

    slow_jazz Lunatic Member

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    I only clean mine when they start acting up.

    Agree with cademan.
     
  6. EchoWars

    EchoWars Hiding in Honduras

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    I don't recommend alcohol. Some mfgr's used plastic lenses and alcohol can permanently fog them. Glass Plus is much safer.
     
  7. Binkman

    Binkman Addicted Member

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    my point is cd players are fragileee! My point was they should be isolated.. I mean how many post have we read where the door doesn't work? skipping etc including damage from handling. Cleaning is one thing one thing but for playback (or recording if you have a device or burning) you got to put it where it won't get a long term beating and isolation.... just like a fine turntable for placement if you want accuracy and clarity.
     
    Last edited: Jul 16, 2014
  8. gonzothegreat

    gonzothegreat Super Member

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    I'm with Echowars on this one. Plastic-safe glass cleaner is the only way to go. Its not like the stuff is expensive.

    If the disc tray is dirty you should clean the entire mechanism since the dirt could eventually make its way back onto the lens. A few times I've removed the laser tray from the player and soaked it in glass cleaner followed by a water rinse and 24 hours in front of a fan to dry. This is only recommended when the qtip method doesn't work but it does get all the dust out.
     
  9. river25

    river25 Super Member

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    How can it sound better? It either works or it doesn't, as it is digital.

    If there are read errors it will go through its error correction protocols. If these can recover the read data then sound is fine. If it cannot correct the errors then it will not play, get a read error or intermittent sound etc.

    Digital consists of only 2 valid states.... on and off... 1 and 0... black and white... work and don't work, etc. If it experiences anything else then it is a logic error and error correction may fix this (depending on the error correction methods) or it won't read.
     
  10. cademan

    cademan Addicted Member

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    River25 is correct about digital and the 0's & 1's (ons and offs) but when a CD player plays a CD and it sounds scratchy on one CD player but sounds clean and perfect on another one, what the hell is that?

    As with the OP, the q-tip and alcohol (or other cleaners) cleared up the scratchy CD on the certain CD player in question.
     
    Last edited: Jul 16, 2014
  11. rudedogg

    rudedogg AK Member Subscriber

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    I have a digital TV, and when it gets a bad signal, the picture gets " distorted" and " pixely" also the sound is garbled...not just off or on....lol
     
  12. river25

    river25 Super Member

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    The distorted and pixelisation is due to too many errors. When that happens you get the effect you see. This is normal as part of the bit stream cannot be determined, hence the artifacts.

    What people often say is the sound quality and/or image quality is lower quality but still listenable/viewable. This is fine in an analog world but in digital it doesn't do that... it gives you the distortion and garble, whcih is what you are experiencing.
     
  13. rudedogg

    rudedogg AK Member Subscriber

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    Yes that's what i mean...so by getting better signal by cleaning my CDP lens, couldn't the sound quality have improved. Or is that my imagination? Of course eliminating the random skipping problem makes sense. I also pushed in all the connectors to make sure they were fully seated. And cleaned the boards and components of dust since i had it opened. I did not realise how easily accessible the laser pickup is. You lift up the pressure plate, it locks in the up position, and wide open access! I never opened up a CDP before...pretty cool
     
  14. river25

    river25 Super Member

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    Digital signals have very defined parameters of what is and is not acceptable. Anything outside of those parameters is an error, as the digital value (whether it is a logic hi or logic lo) cannot be determined. There is error correction circuitry which can, depending on the actual error, provide the necessary correction. However, excessive errors cannot be corrected.

    Yes, cleaning of the lens can assist in fixing tracking/skipping errors. But once the data is read in by the laser - being digital - it is either right or wrong. There is no hi vs lo quality of signal. It is black and white, as that is the whole foundation of digital. It is binary.

    How the CD player deals with a digital error is a another story. The DACs may try and do some fancy interpolation of missing digital signals, which results in garbled or missing elements of sound (and images if talking DVD player showing a video), but it won't give you a "reduced quality" sound.

    When digital input signals are missing or in error, the resultant analog output (through a DAC) would be interprested as moments of silence or glitches in the sound... but not a reduced (ie only goes to 4khz but other than that everyting is sweet) sound quality. I hope that makles sense.

    You mentioned you cleaned up other parts of the player and connectors, and it is possible that may have made a difference. A poor connector can have a high resistance and this would affect the analog output by attenauting it.
     
  15. fiddlefye

    fiddlefye AK Subscriber Subscriber

    I have heard a few things with regard to digital that perplex me, but they were audible nonetheless. Apart from cleaning the lens improving the sound of a CDP (which I have experienced several times) I've also noticed that even using the same identical outboard DAC and connectors there can be noticeable differences in sound, all else being equal. A couple of weeks ago I heard something that really was baffling. I was in the local high-end emporium and a system was playing. I thought it sounded quite good, but it seemed to be have a bit of mid-range suck-out. It turned out the transport had some sort of sprung pad under it. I mentioned the tonal issue, we removed the pad and the balance was back to normal. What was that about? Things in the digital domain are apparently not as simple and cut and dried as one would imagine.
     
  16. river25

    river25 Super Member

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    Actually, things in the digital world are that cut and dried. That is how it is designed.

    However..... how that digital signal is interpreted by the circutry that does the analog conversion is a whole new ball game.
     
  17. fiddlefye

    fiddlefye AK Subscriber Subscriber

    True enough!
     
  18. CT Jim

    CT Jim AK Subscriber Subscriber

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    And the use of one of those cd cleaners with the little brushes achieves the same cleaning of the lens, right?
    General cleaning of the tray and it's accessible moving parts should be done on a regular basis; you determine what regular is depending on usage!
     
  19. jeffj7

    jeffj7 New Member

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    the brushes are not very good, and i have seen a few cases were draging dirt across the lens damaged the lens
     
  20. steerpike2

    steerpike2 Super Member

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    What you are saying is just not true.
    When errors get too big, or too frequent for error correction, error concealment takes over. The digital signal processor (not the DAC) makes 'educated guesses' at what the data should be. A handful of these intermittently you cannot hear, but when they become too frequent, the effect is slightly distorted sound. If it isn't too bad, you may not identify it as real distortion, but the player will sound harsh or edgy. That is indeed 'reduced quality sound'.
     

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