Pioneer cd 906 mods

Discussion in 'DIY Discussion' started by zanash, Feb 8, 2006.

  1. zanash

    zanash

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    For various reasons I'll keep this short, but I hope the owner [chris123] will add a few words as to the performance of the player.

    This is a Stable platform transport, and fairly bog standard inards with a sprinkling of starget caps seemingly at random. There are a number of good things about the design ie the transport but this is let down by the layout of the pcb's and the level of construction. A big downside is that the case with the lid off flexes and has so little rigidity you could see it bend as the unit was lifted. The pcb's are linked with low grade wire, the socketry is particulaly poor, mains input could not be done any cheaper!

    So this gave a lot of scope for modding.....now I hear you all shout why not reclock and be done ? Simple reason is I like to squeeze the most from a unit before I alter the original design. In other words I like to get what the original design team wanted before the bean counters got there hands on it. In most cases this improves cdp's performance but keeps the charactor of the original sound....which was why you originally purchased it.

    The Mods
    fitted about 15 11dq10 schottky diodes in the various power supplies
    Fitted good Quality RCA sockets and wired to the board with solid core silver in ptfe. For both phono and spdff .

    At critical points in the signal path cheap caps were replaced with silmics, silmics were also used as bypass caps on some of the bigger psu resovoir caps along with a shed load of wima film caps on most of the smaller caps in the dac and analogue output.

    The analogue side was barely touch as this unit feeds a NOS DAC so really there was little point in wasting time money and effort...I'd already been let loose on the NOS with very intresting results.

    The mains lead and internal mains wire were replaced using a good three core 20 amp shielded type and soldered straight to the psu pcb's rather than the long pins as before. I was going to fit an IEC socket but realised that this would entail too much work to cut through the two plates that make up the back plate assembly, so when for they flying lead approach.

    Strengthening the case and damping the unit ammounted to a high proportion of the rebuild. I used the metalized bitumen roof flashing strip. I covered the whole of the base after removing the nasty plastic feet. The lid, sides, and back plate along with cutting out shaped peices to fit the transport. The draw and mechanism was loaded with two giant packets of blu tac, making the tray stiffer and throughly damped. The dac pcb sits on its own metal tray so this was removed and bitumen damped.
    All the Chips where also treated along with the crystal. In all an extra 2kg was added to the mass of the player.

    So how does it sound ....thats not for me to say in any detail. But its worth saying that once I'd discovered why it kept skipping in the same place what ever the disc ! The sound was very nice indeed. What for me were the real gains was the improved level of resolution, instraments all now had space to play in. Small details in the sound were now clearly evident, where before you were not even aware they were there.

    Thanks to Chris123 for letting me play with his CDP and if he's got time before his big day perhaps he'll add a few details.

    Before I forget I'll wish him "All The Best" and I hope everything goes to plan!
     
    zanash, Feb 8, 2006
    #1
  2. zanash

    chris1968

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    Apologies for the delayed response but wedding plans, stag do etc etc have not left me with much time to do 'owt since i collected the CDP from Pete.

    Given that Pete tweaked my NOS, showed me just how good silver cable can be, showed me what happens when you selectivley use a green pen and tweaked the CDP in a matter of a week its hard to quantify just what effect the CDP tweaks had (i'm an 'overall' listener as opposed to a 'critical' listener, add to that a lack of prose when trying to translate thoughts to the written word and i'm all but useless onthis kind of fora) - however - to sum up

    Overall comments then (which they have to be give the 'en-masse' tweaking!!) is that the system is far more musical (veils have been lifted, feet are tapping!), great improvements across bass, mids and highs (must order those bass traps!), more detailed (i can hear little 'sighs' as valves open / close on certain brass instruments / tracks) and more natural - vocals are great and its like some of my disks have been 'green penned' but they have not (yet!) - strings, drums, accoustic guitar, violin, piano etc etc just sound so much better.

    Trying to isolate the effects of the CDP tweaks, is, to me tricky but bass is certainly deeper and highs are higher, there is more detail and sound is more natural - wonder is that is cos the nos is getting a better 'feed', as well as the fact it was also tweaked!

    Next steps (once there is a penny or two back in the bank) is to look into getting the beast clocked (from what i hear / read that should ice the cake as it were!) i would also like to hear a dedicated PSU with the NOS though comments elewhere mostly relate to the psu bolstering the bass and, to be honest, improvements have been so good so far i cant see how the PSU could lift things further...time will tell

    Thanks again Pete!!

    Chris
     
    chris1968, Feb 19, 2006
    #2
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