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    Clarity TC film caps in the power supply

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    Captain Coconut

    Posts : 216
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    Age : 64
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    Clarity TC film caps in the power supply

    Post by Captain Coconut on Thu Apr 10, 2014 10:41 am

    I've been itching to try the Clarity Cap TC film caps in the power supply of a ST-35 build - on a larger chassis of course. The original ST-35 used a 450Vdc rated electrolytic can cap on the power supply. I use a 550Vdc rated can cap with a 600Vdc surge rating.

    Clarity Cap offers a 450, 600, and 700Vdc cap, among others. Is the 450Vdc enough - the original used it - or would the 600Vdc be a better solution, giving more headroom. I know that you shouldn't go too far beyond the voltage a cap "sees" in order for it to form properly, so I wonder if 600 is too large. The operating voltages are roughly 385-380-320 for the three stages of ST-35. I'll be using higher uF values by the way.

    Thanks for any help

    Jim McShane

    Posts : 154
    Join date : 2011-10-19
    Location : South Suburban Chicago

    Re: Clarity TC film caps in the power supply

    Post by Jim McShane on Thu Apr 10, 2014 11:42 am

    Captain Coconut wrote:I've been itching to try the Clarity Cap TC film caps in the power supply of a ST-35 build - on a larger chassis of course. The original ST-35 used a 450Vdc rated electrolytic can cap on the power supply. I use a 550Vdc rated can cap with a 600Vdc surge rating.

    Clarity Cap offers a 450, 600, and 700Vdc cap, among others. Is the 450Vdc enough - the original used it - or would the 600Vdc be a better solution, giving more headroom. I know that you shouldn't go too far beyond the voltage a cap "sees" in order for it to form properly, so I wonder if 600 is too large. The operating voltages are roughly 385-380-320 for the three stages of ST-35. I'll be using higher uF values by the way.

    Thanks for any help

    Film caps do not "form", only electrolytics do. So you can discount that factor. You can use larger voltage film caps if you like and don't mind the expense and/or their size!

    As far as the voltage rating - select the worst case voltage and add a bit to it. Don't neglect to figure you could easily experience a 5-10% high AC line voltage which would add about 30-35 volts to the B+. So if the B+ is 385 or so then worst case would be about 425. 450 should do just fine, but 600 would be fine as well.

    corndog71

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    Re: Clarity TC film caps in the power supply

    Post by corndog71 on Thu Apr 10, 2014 12:01 pm

    The most readily available versions are the 600 and 700 volt TC caps from Partsconnexion.  It looks like all they have left of the 700V are 45uF.  I just picked up a bunch of them as they are on clearance.  The newer 600V versions are supposed to be slightly improved.  

    In my original ST35 build I used Panasonic electrolytics in the power supply and it sounded really good.  When I rebuilt it with the TC caps a layer of haze vanished from the overall sound and clarity and transient speed improved.  Bass definition improved as well.  Since the ST35 uses just a CRCRC filter you could probably just go with 4 of those 45uF caps.  Parallel 2 of them for 90uF in the middle to better drive the output taps.

    The trickiest part is figuring out how to mount them.

    Captain Coconut

    Posts : 216
    Join date : 2009-10-13
    Age : 64
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    Re: Clarity TC film caps in the power supply

    Post by Captain Coconut on Thu Apr 10, 2014 1:09 pm

    Thanks for the input Corn. Jim, thanks for the clarification. A couple of prominent contributors in another forum talked about higher voltage rated film caps being harder to "form". I just went along, seeing that they were more "qualified" than I.

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