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    ST-120 Amp ESl Capacitors

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    geode

    Posts : 6
    Join date : 2015-04-16

    ST-120 Amp ESl Capacitors

    Post by geode on Mon Apr 20, 2015 4:25 pm

    The amp kit has three film caps in the values of 1.0uF, .1uF, and .01uF. All three are connected in parallel. Can I use one 1.5uF Film cap rated at 600VDC instead of the three. I have several good PolyPro film caps on hand. Anybody see any problems upping the values to 1.5uF for this ESL cap.

    corndog71

    Posts : 444
    Join date : 2013-03-19
    Location : It can get windy here

    Re: ST-120 Amp ESl Capacitors

    Post by corndog71 on Mon Apr 20, 2015 4:41 pm

    I think just a 0.1uF would be adequate. It's just a bypass cap.

    geode

    Posts : 6
    Join date : 2015-04-16

    Re: ST-120 Amp ESl Capacitors

    Post by geode on Mon Apr 20, 2015 5:57 pm

    corndog71 wrote:I think just a 0.1uF would be adequate.  It's just a bypass cap.

    Thanks Corndog. So, the 1.5uF wouldn't be a problem. I have these caps and am itching to install them somewhere. I'm also chasing a low level hum in the left channel only. The hum is constant and isn't influenced by the attenuator. I'm thinking some wire might need re-routing. Already moved all the tubes around.

    Bob Latino
    Admin

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    Join date : 2008-11-26
    Location : Massachusetts

    Re: ST-120 Amp ESl Capacitors

    Post by Bob Latino on Mon Apr 20, 2015 8:09 pm

    geode wrote:The amp kit has three film caps in the values of 1.0uF, .1uF, and .01uF. All three are connected in parallel. Can I use one 1.5uF Film cap rated at 600VDC instead of the three.  I have several good PolyPro film caps on hand.  Anybody see any problems upping the values to 1.5uF for this ESL cap.

    Yes - you can ...

    The newer VTA ST-120's (and M-125's) now have just a single 1.0 uF @ 630 volt ESL bypass cap. The two smaller caps were found to not really be necessary. The purpose of the ESL cap is to act as a "bypass cap" for the high voltage system. This cap gives the high voltage system a low impedance path to ground and helps break up any resonances in the larger caps.

    Bob

    geode

    Posts : 6
    Join date : 2015-04-16

    Re: ST-120 Amp ESl Capacitors

    Post by geode on Mon Apr 20, 2015 10:35 pm

    Bob Latino wrote:
    geode wrote:The amp kit has three film caps in the values of 1.0uF, .1uF, and .01uF. All three are connected in parallel. Can I use one 1.5uF Film cap rated at 600VDC instead of the three.  I have several good PolyPro film caps on hand.  Anybody see any problems upping the values to 1.5uF for this ESL cap.

    Yes - you can ...

    The newer VTA ST-120's (and M-125's) now have just a single 1.0 uF @ 630 volt ESL bypass cap. The two smaller caps were found to not really be necessary. The purpose of the ESL cap is to act as a "bypass cap" for the high voltage system. This cap gives the high voltage system a low impedance path to ground and helps break up any resonances in the larger caps.

    Bob

    Thanks Bob. Just checking to be sure.

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