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


    SP14: two issues and need some help

    Share

    Laminarman

    Posts : 110
    Join date : 2009-12-30

    SP14: two issues and need some help

    Post by Laminarman on Thu Mar 13, 2014 5:55 pm

    The SP14 is a few weeks old, sounds fabulous, quiet and dark. Unless I touch the chassis then the right speaker transmits the sound. I took the thing apart, I cannot find anything touching or where it should not be. Is this a grounding issue? I have the black mat below the PCB. If I tap the chassis, the right speaker sings. Unrelated I think, is that rarely (5% of the time) the left channel suddenly fades and goes out, then comes back. Not a "cut out" but quick fade in and out. Also, the left gain will, ON OCCASION, cut out when turning up the gain, then turn right back on. The unit is awesome but these two issues perplex me and i hate to leave it as is especially if it will ruin something or be dangerous as in the case of a ground issue.

    pigface

    Posts : 70
    Join date : 2011-04-10
    Location : pittsburgh

    Re: SP14: two issues and need some help

    Post by pigface on Thu Mar 13, 2014 6:19 pm

    I just had a similar problem with mine with the tapping sound transfering through the speakers . Mine was  slightly microphonic tubes .  Try switching around the  far left two  tubes with the center pair of tubes  . The gain section might be amplifying a microphonic tube . I did this and my problem went away . Mine was on both channels , you might only have one noisy tube .
     I cant help on the other problems .

    Laminarman

    Posts : 110
    Join date : 2009-12-30

    Re: SP14: two issues and need some help

    Post by Laminarman on Thu Mar 13, 2014 6:26 pm

    I'll try that, thank you.

    Zimmer64

    Posts : 112
    Join date : 2013-01-29
    Age : 52
    Location : Switzerland

    Re: SP14: two issues and need some help

    Post by Zimmer64 on Fri Mar 14, 2014 2:18 am

    This sounds like a grounding issue. I suggest to check the grounding vs. the schematic again. The fading sound could be a cold solder joint. I always check all my solder joints by taking high rez photos and zooming in on those on my iPad.

    Best

    Michael

    Laminarman

    Posts : 110
    Join date : 2009-12-30

    Re: SP14: two issues and need some help

    Post by Laminarman on Fri Mar 14, 2014 8:32 am

    Zimmer64 wrote:This sounds like a grounding issue. I suggest to check the grounding vs. the schematic again. The fading sound could be a cold solder joint. I always check all my solder joints by taking high rez photos and zooming in on those on my iPad.

    Best

    Michael

    I've double and triple checked grounding schematics but I'll do that again. Yeah, I wondered about the solder joints. What would I look for, a dull gray instead of shiny gray joint?

    Zimmer64

    Posts : 112
    Join date : 2013-01-29
    Age : 52
    Location : Switzerland

    Re: SP14: two issues and need some help

    Post by Zimmer64 on Fri Mar 14, 2014 9:49 am

    Yes. Look for a cold joint. They are dull grey.

    Sponsored content

    Re: SP14: two issues and need some help

    Post by Sponsored content Today at 7:45 pm


      Current date/time is Thu Sep 29, 2016 7:45 pm