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    Recap a PH-12?

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    vtshopdog

    Posts : 60
    Join date : 2015-07-11
    Location : UT, USA

    Recap a PH-12?

    Post by vtshopdog on Sat Apr 02, 2016 6:14 pm

    Hello

    Opened up my VTA SP/PH 12 to replace the stock scratchy dual mono gain attenuators that have been bugging me for a while.  Don't have a project going at the moment and the slippery slope of OCD-guy mission creep has set in.  Now I'm pulling boards out of chassis, rewiring portions, replacing resistors and have new coupling caps on order for the SP-12.  

    My question - has anyone tried upgrading the Panasonic(?) metalized polyester output caps on PH-12?  I won't throw boutique parts in this position, but maybe some sort of basic polypro can be shoe horned in there.  Thanks for any input.

    Cheers,
    Tim

    tubes4hifi
    Admin

    Posts : 1261
    Join date : 2008-11-30

    Re: Recap a PH-12?

    Post by tubes4hifi on Tue Apr 05, 2016 8:41 pm

    I don't know who used polyester caps in there, as the standard supplied is generic polypropylene,
    but here's some options for upgrades . . .

    Solens should be slightly better at about $3 each.

    SoniCaps would be better at about $7 each.

    AudioCap Theta would be better at about $13 each.

    Mundorf EVO SGO would be super good at about $28 each.

    vtshopdog

    Posts : 60
    Join date : 2015-07-11
    Location : UT, USA

    Re: Recap a PH-12?

    Post by vtshopdog on Wed Apr 06, 2016 12:54 am

    Thanks Roy, having some fun with this mini project.  

    (BTW have Polypropylene in there now, but bad ID job on my part from limited markings on the generic case)

    The Mundorf EVO series are best dimensionally as they are stubby little guys with multiple available models ranging from basic $5-ish on up to the (more-than-I'm-gonna-spend) SGO's.  Have some EVO oils picked out that are reasonable price and dimensions.

    Two more questions:
    I can't locate any information regarding use of the trim pot resistors on PH 12 board - can you shed light on this please?

    Second, since I'm swapping coupling caps on SP-12, would upgrading either of  the C4 and/or C6 position(s) be beneficial?  It has stock red Interchink Audyn 0.1 uF now.
    (are redundant solder pads on the board the prime upgrade points in the circuit??)

    Thanks, Tim

    tubes4hifi
    Admin

    Posts : 1261
    Join date : 2008-11-30

    Re: Recap a PH-12?

    Post by tubes4hifi on Wed Apr 06, 2016 9:45 am

    trimpots on PH12 are set to center position unless the gain of one channel is more than the other, than turn pot(s) to compensate,
    this info is in the lastest set of docs.
    For SP12 cap upgrades, only the two large outputs are in the signal path. C4 & C6 are in power supply.

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