Generic CD Player Mods

Discussion in 'Hi-Fi and General Audio' started by zanash, Jun 9, 2005.

  1. zanash

    zanash

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    [snip][leftnews]http://www.zerogain.com/forum/gas/images/1/1/4/1/2cd.jpg[/leftnews]Today I'll be taking you through some mods for your average CD Player. Whilst this isn't a full or final list, the things you can do are nearly limitless with the right imagination and a steady soldering iron, so add a little life back to that flagging CD Player - you may just surprise yourself...![/snip]Today I'll be taking you through some mods for your average CD Player. Whilst this isn't a full or final list, the things you can do are nearly limitless with the right imagination and a steady soldering iron, so add a little life back to that flagging CD Player - you may just surprise yourself...!


    Methodology

    I prefer to try and get the best from the circuits as they stand rather than rip out and replace. The designer must have had some aim in mind when he produced the design...?


    Case Work

    The thin pressed steel casework will need damping... foamed butyl rubber sheet or bitumen damping panels as used in the motor trade work really well. The lid and base will need damping as well, don't forget. The transport and draw mechanism can be treated in a similar way. But don't foul the workings with too much.

    A blue led shone onto the disc also has an effect [don't ask why as I don't know]. A green poster paint pen like the Posca pens by Uni can be used to put a green ring round the edge of CDs [including the inner hole]. If the case work is sprayed green on the inside [big job to remove all the working and mask up] this will help cut down the stray infra red scatter from the laser. The green shade depends on the freq. of the laser so a bit of trail and error is normally involved. Try getting two identical CDs and paint the edges of one... when dry do a bit of DBT. I find that the green one often sounds more relaxing [but not always].


    PSU

    Fit a decent mains cable from inlet to CDP board.

    Check the thermal compound on the regulators, and upgrade to a silver based compound.

    Replace diodes with Schottky types of suitable rating like 11DQ10's. As these work on a different principle to the normal diodes they have none of the draw backs like reverse current generation and RF production. In effect they are much quieter and I've found them pound for pound to be one of the single best upgrades you can make.

    Replace the reservoir caps with Audiophile types and then
    bypass them with values of 10% i.e. a 1000uf with 100uf, 10uf with 1uf, the theory being that smaller caps respond faster to transient power demands, making for a faster and more detailed sounding player.

    Look at the quality of the power supply wires to the various parts - use a high quality copper or silver wire with Teflon insulation; routed to cross the unit at right angles to other cabling.


    Output Stages

    First look to remove any muting transistors, just snip them off the board. These things are switched on when you press the next track or skip buttons, reducing the slight popping noise created by diverting part or all of the output to ground and thus muting the player. But as the transistor never actually switches off, a small amount of output is constantly drained to ground... never a good idea. The difference after removal is considerable in the scale of tweaks.


    Op Amps

    There are any number on the market ranging from a few pounds to tens of pounds [more expensive is not always better] its often a matter of personal taste, my low cost favourite is the Bur Brown opa2604, 604 for the mono. Remove the original op amp and solder in a high quality socket - I use ones with Beryllium Copper legs. This allows for easy swapping; even with the extra connections this set up sounds better than the original in all the players that I've made the change on. As most op amps work at such a low level, the can actually be operating in class B or C. It's worth putting a constant load on the output to raise the operation into class A. There are lots of websites that give you the instructions in how to do this, but remember that in class A 50% of the output is going to be heat! You need to address that problem and add a heat sink to the op amp.


    Signal Path

    The replacement of the resistors in and around the signal path will also remove a veil from the sound… as a minimum, use Holco's precision metal film [0.01% tolerance], but there are a lot of expensive good ones about i.e. Vishay bulk foils or Audio Note Tantalum's etc.

    Replace the copper tracks on the PCB with silver wire [Hard work! Not to be attempted unless really confident...]


    Clock

    Replace the following with its own power supply: Trichord Research Clock 4 or similar.

    Consider non oversampling [this of course is specific to the DAC in the machine].


    RF / EMI

    Copper foil shield all IC's and bundle and wrap all cables in foil, which must then be grounded to a convenient point on the case work. Cut the foil to size and stick to the top of all the IC's - use a small wire and solder the foil to the ground leg of each IC. Look to make a copper sheet screen to shield the PSU from the drive and the drive from the output stages.


    Shorting Plugs

    Build a shorting plug for the digital output: http://diyparadise.com/75ohmtweak.htm


    CD Output

    This can be high and might be the cause of overloading the input stages of the preamp… simply use a plug in attenuation or add the appropriate resistors to the IC plug.


    Tubes [For players like the Jolida XXXs]

    I like Svetlanas for me they give a velvety inky black silence and a smooth warm effect in there presentation, but these are a very personal choice.


    Dislikes and Don'ts

    I'm not a great fan of black gates… they take years to burn in, so you will never get their full benefit - their cost is prohibitive to.

    I like Elna Stargets in and around the PSU and output stages… they are cheaper and give an honest performance straight from the box. Replace all the caps [not already swapped] with Oscons [sg?] you can use the copper legged ones, especially around the digital section.

    Don't use any ferrite beads… they will squash the dynamics of the system.


    Out of Box Things to do

    Make or buy a decent shielded mains lead... these act as filters removing grunge and cack before it gets to the player. Look to use a mains conditioner beyond the power cable, and use decent wall plugs. Don't neglect to clean all metal contacts. Metal oxides act as diodes.

    Feet... well a simple three point system of cones will be effective - there are many on the market to suit all pockets but if you are like me, you may prefer the DIY approach. Try some domed hard wood cupboard door knobs [approx 10mm dia]. These work as well as anything.

    The support should be a vibration absorbing sandwich on a sand box. I use 2 layers of 5mm MDF separated with a sheet of foamed butyl rubber - kills vibration by an average of 20%, more for high frequencies. The sand box is a box full of sand [oven dried] with a sheet of MDF sitting on the levelled sand, but clear of the sides of the box by a few mm.

    Build the best IC you can - for me at the moment this is a simple twisted pair of solid silver 4N wire in a Teflon sleeve with bullet plugs, fabulously revealing but not as overly bright as you might expect or have been told.

    In my opinion you can achieve a lot by cleaning the pins of the mains plug so they shine, use Duraglit or other metal polish, and don't forget the fuse ends and the holder. In the UK the fuse is in the wall plug. A good fuse has copper caps but they are often covered in soft solder [tin and lead] - once removed, the difference is clearly audible. Also if the CDP has valve output stage, clean the pins on the valves.
     
    zanash, Jun 9, 2005
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  2. zanash

    mudgey

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    I can certainly appreciate all the tweaks you are stating, but how the heck do you recognise these items in your player?
    Pictures pointing out the various parts would be ideal for us non electronic types, but some of us can can use a soldering iron.

    Appreciate your information
     
    mudgey, Oct 31, 2005
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  3. zanash

    cbandera

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    Modding switching PSUs

    Very nice article.

    I bypassed the mute circuitry on a Pioneer DV-45A SACD/DVD-A player with incredible results. So sad that Elite would have sacrificed so much sound quality to save on the cost of a little relay. At least they got the D/As and the op-amps right; the latter run class-A with a 6V bias that, until I install a muting relay, makes for a serious power-on pop when the volume is up.

    My next step is to dampen the bridge rectifier as you describe. Because the swiching power supplies in these lightweight players are often underdesigned (the first things to blow), I suspect any reduction in rectifier noise will be noticeable. The scope shows tremendous amounts of switching noise on the PSU outputs (moreso on the digital rails).

    Question: switching PSU's have several transformers (primary, high frequency, etc.) crowded on a board with little room for sand resistors. Any thoughts as to which transformer(s) to attack first?
     
    cbandera, Dec 13, 2005
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  4. zanash

    mike lacey Akiverer

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    Wow, what a great post.
     
    mike lacey, Feb 13, 2006
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  5. zanash

    kenneth cooke

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    Or buy a decent CD player in the first place
     
    kenneth cooke, Jul 18, 2006
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  6. zanash

    zanash

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    Ah yes if money is no object .....but I feel your post misses the point even in jest.
     
    zanash, Aug 3, 2006
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  7. zanash

    mr cat Member of the month

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    where can I buy - foamed butyl rubber sheet or bitumen damping panels online from..?
     
    mr cat, Aug 18, 2006
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  8. zanash

    aquapiranha

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    From here for example, used widely in car audio applications on door panels etc..

    http://www.raysmith.co.uk/Dynamat/DYN10125/
     
    aquapiranha, Aug 18, 2006
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  9. zanash

    Sid and Coke

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    Although perhaps a little more hassle why not use some kind of adhesive sealant for damping down case panels, using something like silicon window or bathroom sealant would probably have a positive effect. I've been meaning to do this on my Rotel Phono stage, (even if i think its effects may be minimal at best). I would use Polysulphide Aircraft Fuel Tank sealant as i can get hold of it easily. It is a conformal coating and adheres to degreased surfaces like a limpet , once it has cured it has the same compliant consistancy as rubber ( Rubber as in; a Pencil eraser...) . PR-1422 A2 made by PRC-DeSoto is a typical product.
     
    Sid and Coke, Aug 19, 2006
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  10. zanash

    mr cat Member of the month

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    mr cat, Aug 21, 2006
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  11. zanash

    mr cat Member of the month

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    this arrived yesterday (actually - they've ran out of dynamat but offered a better solution called Skinz) and this was just enough to do my Cdp and dvd player - I first done the cdp but I haven't had time to test this - but I maybe there won't be that much of an improvement as the stereo amp sits on top ofthe cdp.

    a review of my dvd a few years ago by what hifi suggested that one places a weighted object on top of my dvd player - so Iwas expecting some improvement there...I when I played a dvd (saw 2) and I noticed a big improvement straight away - the weight of the sound is much better - if that makes any sense!
    the sound from the rear channels have also improved.

    well worth the investment I think...do you think this sheeting would improve my amps too..?

    cheers
     
    mr cat, Aug 24, 2006
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  12. zanash

    zanash

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    case work and damping are often ignored by the makers ...try it and see!
     
    zanash, Aug 24, 2006
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  13. zanash

    zanash

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    DC blocking caps.......
    these are found to almost the last component before the output sockets after the opamps in the signal path.

    If you've not tried film caps or the more exotic PIO's [paper in oils] its quite unbeleavable how electrolytics and especially bipolars can emasculate the sound ...

    the downside is pio are large and its often a squeeze to find suitable space to shoe horn them into the case.
     
    zanash, Nov 18, 2006
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  14. zanash

    felix part-time Horta

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    That also applies in cd players using coupling caps between the DAC chip itself and the analogue stage. Because the stage impedances are usually reasonably high the capacitance values can be quite small, allowing use of reasonable-size parts like Wima FKP parts.
     
    felix, Nov 18, 2006
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  15. zanash

    carlejo

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    Hi Guys .... new to this forum but this has made a very interesting read....

    Zanash, are you from an electronics background ?..... I frequent another AV forum and it deals with everything except DIY stuff really..... however, there is a guy on the site that has just let board members "loan" some things that are placed directly under CDP, DVD, amp, etc...... apparently it offers damping qualities and isolates any electrical inteference and vibration....... is this what the butyl rubber does ?..... the reason I ask is that the four feet that were supplied were covered in a protective coating so that the product could not be seen.... to squeeze, it did feel like an eraser like you would use in school, only a little harder......these thing did make an substantial improvement under my Rotel RA02.... RA01 did not have any damping at all as I only had one set(of 4) to lend.... bass seemed tighter and more controlled..... the guy from the forum has said and I quote "it makes a £500 CDP sound like a £2000 CDP".... the cost, £70 for a set of 4
    Any thoughts on this....
    cheers
    Carl
    :mana:
     
    carlejo, Dec 21, 2006
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  16. zanash

    zanash

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    The material sounds like sorbthane .....the butyl rubber mat cost £20 1x2m sheet .....£70 sounds rather a lot for four ....If you want to try some virtually free feet, get some wick large floor tile spacers the ones that have holes in them. Thread one at right angles through another to make a caltrop. Sit your cdp on top of these and be amazed !

    if your cdp is too heavy you can stack thes spacers togeter with a blob of blutac to glue them together.

    Also remember that three feet will be better than four...triangle of stability etc. place one under the transformer and one under the spindle and the other to balance the unit.

    I'd be sceptical about the electrical isolation [though they may have some anti static properties] of these squishy feet, they sound like they are doing the standard vibration absorbtion.

    I've also heard good results from small cinder blocks and those foot scrubbers [see TNT audio].......

    As a paid up member of the cheap skates club I'd be very warry of things costing that much ......especially as I've not got first hand experience with them !
     
    Last edited by a moderator: Dec 22, 2006
    zanash, Dec 22, 2006
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  17. zanash

    carlejo

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    Thanks for the reply... not sure what you meant by above statement with caltrips, etc.... could you help me a little more please.

    also, where can I get this sorbthane ?..... and can you explain in laymans terms about vibration absorption ?..... not sure on the weight of the Rotel RCD02, but i'd like the best method to enhance CDP without taking apart and making mods....

    thanks
    Carl
     
    carlejo, Dec 22, 2006
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  18. zanash

    T-bone Sanchez

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    Hey Z

    any experience with the zapfilter?? Im going to be working on my cdp in the new year (want to get rid of the dac) and looking to try one. I have a flea pcb so the clock is sorted.
     
    T-bone Sanchez, Dec 22, 2006
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  19. zanash

    zanash

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    No but only heard good things !

    Sorry not wanting to sound obtuse ...

    google caltrop !

    If you have a decathalon store look at the 18mm blue exercise mats ...thats the material I used.
     
    zanash, Dec 22, 2006
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  20. zanash

    peez

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    Hi Zanash, I have a micromega stage 4, got the lid off at the mo and am in the process of ordering a (better) mains cable but wouldnt know what a muting transistor looked like if it bit me, any ideas? Have pliers and ready to snip snip snip!
    Great article too mate.
     
    peez, Dec 30, 2006
    #20
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