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Thread: CDP mods

  1. #1

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    Default CDP mods

    I've been thinking about a new source or a dac.
    But while I ponder, I took my old AMC cd8b and tried an easy mod.
    I pulled the muting transistors out. Wow. The highes came alive.
    That was WAAAY too easy. Next stop: chip changes.

  2. #2

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    Nice going. It's amazing what little mods can do. After that, open the wallet or buy "THE CDP MOD BOOK" by F1NUT.
    Michael ;)
    In the beginning, all knowledge was new!

    NORTH of 60

  3. #3

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    Tell me more on the muting transistors, my CD8B is my daily driver on the whole house rig with an Entech D/A.

    Cheers,
    Russ
    Check your lips at the door woman. Shake your hips like battleships. Yeah, all the white girls trip when I sing at Sunday service.

  4. #4
    GV#27
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    Quote Originally Posted by RuSsMaN View Post
    Tell me more on the muting transistors, my CD8B is my daily driver on the whole house rig with an Entech D/A.

    Cheers,
    Russ
    That Entech is a nice little DAC that should be easy to mod.I would look at upgrading the op-amps in the analog output stage.Can't remember but I think it uses an OP275 which is good but can be improved upon.Also If it has any output coupling caps I would remove them.Also adding a higher current outbourd power supply to replace the wall wart may be benificial.

    oops sorry Russ I guess it was just the player not the DAC you wanted to mod.
    Last edited by GV#27; 07-04-2007 at 09:54 PM.

  5. #5

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    If you are using an external DAC, this mod won't do anything. The muting
    transistors kill the analog output when switching on or off the CDP.
    This stops the little pop sound. The transistors in the circuit pull down the high end output a bit. Removing them adds sparkle to the high end.
    I've already added Dynamat, and replaced the cheap board mounts with
    real screw down standoffs.

  6. #6

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    Russman, how does the Entech DAC sound VS the the stock AMC sound?
    Big difference, litlle difference? I know the Entechs are modestly priced
    and I'm wondering if I'm just wasting my time fooling with mods if an
    affordable DAC would get the job done.

  7. #7

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    Dynamat the base and lid, almost always makes a reasonable difference.
    madmax
    Vinyl, the final frontier...

    Avantgarde horns, 300b tubes, thats the kinda crap I want... :D

  8. #8

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    Already been Dynamatted.
    For reference, the muting transistors are q423 & 424 next to the
    rca output jacks.
    Now, I'm stumped. The info I had said they had tl072 chips for opamps.
    Seems I've got a newer one with ne5532n's. Better chip. The adc8610's
    may help, or may be too bright. Damn. Guess I'll just have to take a leap of faith. I'm gonna look up some other improvements while the top is off.
    And get a bigger magnifying glass.

  9. #9

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    Found some machined 8 pin ic sockets and some ne5532's(same as stock)
    op amps. Got enough fast recovery diodes to change out all of the current ones in the PS of the AMC cdp.
    I cut out and removed the ne5532n's, soldered in sockets, and changed to the FRED diodes.
    The spare NE5532's were of the NE5532ap(TI) rather than NE5532n(Fairchild). Supposed to be
    slightly better. Fired it up, WOW. The bass is there. The drum hits are there with authority now.
    More weight to vocals. Had to stop to get a PAS pre from RUSSMAN(to be tested later:D ).
    Listening last night to Joe Satriani/Joe Satriani, the treble is still there, just more body in the mids
    and harder hitting bass. More testing today. The DIY guys weren't joking when they said
    FRED's in the power supply would make a big difference. This is without a major OPamp changout.
    Time to pop the top on the Acurus acd11 and do the FRED diode mod. I even gave up and bought the geeky magnifying flip down visor. 20 years ago I used to laugh at a guy for soldering with those.
    Damn getting old.

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