The Dynaco Tube Audio Forum

Dedicated to the restoration and preservation of all original Dynaco tube audio equipment - Customer support for Dynaco VTA tube amp kits, all Tubes4hifi.com products and all Dynakitparts.com products


    Mid priced attenuator upgrade suggestions for my SP-12?

    Share

    vtshopdog

    Posts : 69
    Join date : 2015-07-11
    Location : UT, USA

    Mid priced attenuator upgrade suggestions for my SP-12?

    Post by vtshopdog on Thu Aug 27, 2015 3:54 pm

    The twin L/R gain attenuators on my SP-12 built in '13 have always been scratchy at best.  (master volume seems OK)  They come around for a while with some Deoxit but contacts on some positions only work with a little back and forth motion on the knob and are prone to cutting out.  Upgraded the selector switch to a Goldpoint right out of the gate to solve a cross talk issue with stock switch and quite like that, but don't want to throw Goldpoint $$$ at 3 attenuators.  

    Going to have the SP box opened up when my M-125 build is done next month, so that's logical time to get at the attenuators.  The scratchy gain switches have to go and might as well do the master volume while I'm at it.

    Anybody  have suggestions?  TubeCad/Glass Ware guy has some OK looking DIY stepped kits for $20-50 range and I've seen a bewildering array of Chinese Ebay type items, some of which are likely great values and others that are doubtless junk (but which are which??)

    Thanks, Tim

    tubes4hifi
    Admin

    Posts : 1286
    Join date : 2008-11-30

    Re: Mid priced attenuator upgrade suggestions for my SP-12?

    Post by tubes4hifi on Sat Aug 29, 2015 6:54 pm

    Tim,
    for the past two years I've been supplying the preamp kits with the same 21 step volume control that Bob has as an add-on for VTA70 buyers.
    They work just as well as Goldpoints at triple the price.   They are made in China, but they work well.
    Even though they are stereo, I just wire the two side (gain/balance) pots mono.    Haven't found anything better for less or for double the amount.

    vtshopdog

    Posts : 69
    Join date : 2015-07-11
    Location : UT, USA

    Re: Mid priced attenuator upgrade suggestions for my SP-12?

    Post by vtshopdog on Sat Aug 29, 2015 8:10 pm

    Thanks Roy

    I had not even considered using half a stereo dact type attenuator for the mono gain adjustment.
    Think I might have a couple of those laying about from another project but will have to find them to relearn what value I purchased and did not install. Am I correct in remembering stock value was 100K?? (10x 10K series resistors soldered around radius of the scratchy switch)

    Cheers

    tubes4hifi
    Admin

    Posts : 1286
    Join date : 2008-11-30

    Re: Mid priced attenuator upgrade suggestions for my SP-12?

    Post by tubes4hifi on Sat Aug 29, 2015 8:44 pm

    yes, I use the 100K value, but it's not critical

    Sponsored content

    Re: Mid priced attenuator upgrade suggestions for my SP-12?

    Post by Sponsored content Today at 10:27 pm


      Current date/time is Sun Dec 04, 2016 10:27 pm