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GSC make crappy audio caps

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    #1

    GSC make crappy audio caps

    So this weekend I decided it was time to blow the dust out of some of my equipment. I have a Klipsch Promedia DD-5.1 digital decoder preamp box that I use for input switching. It's been running really hot as of late, so I figure it must have some dust it in. I crack open the case, and there's no dust to be found. What there is however, is a case full of GSC caps. None are blown, but that can't be good.

    I have no idea what the original grade of caps were, as I can't find any series markings. I've read in several places that Panasonic FC is "not bad" for audio. So I went with those. Recapping it was actually quite tricky. The board was thick with lots of copper, and cheap solder mask that flakes off way too easily.

    It's now full of FC and back up and running. I think it sounds much clearer now, but that could just be in my head. Or maybe not. I measured some of the GSC caps that I removed and ESR was all over the place. The 25V 10uF caps that were in line with the signal path ranged from 1.5 - 36 ohms ESR! yikes. Would these be filter caps? I'm not used to working with audio stuff. Even the larger caps in the power circuitry showed similar variation in ESR.

    So, while I'm not 100% sure the FC ratings are as good as the GSC ratings, the FC installed was drastically better than the GSC removed in every case. It was working fine even with the questionable GSC, so it's definitely an improvement. I'll keep an eye on the FC going forward.

    I ordered some heatsinks for the power mosfets, as there was some discoloration on the board. If anybody is curious, I can post photos of the repair when those come in and I crack it open again to install the heatsinks.
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    #2
    Re: GSC make crappy audio caps

    The 10uF caps in the signal paths were probably coupling caps. Their ESR doesn't really matter in that application, but since it was all over the place their capacitance (uF) values could have been all over the place as well, affecting the sound.
    Originally posted by PeteS in CA
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      #3
      Re: GSC make crappy audio caps

      Panasonic FC is great for audio, i use em for my altec lansing mx5021 mod.

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        #4
        Re: GSC make crappy audio caps

        Probably still good to use low ESR in audio apps especially if it's the actual audio signal.
        In that case makes sense to use caps w/ESR optimized for 10uF [approx half way in range 20Hz-20kHz].
        The 10uF Panny FC 50v 5x11mm has about half the ESR of the 10uF FC at other voltages as well as most other brand/series at any voltage.
        The correction from 100kHz to 10kHz is 0.90 in FC data sheet so that cap has ESR of 1.30 x 0.90 = 1.17 at 10kHz.
        .
        The 'what is better than what' we get used to for typical mobo and PSU size caps 8-10-12.5mm] does not apply to the tiny caps.
        IOW: 'what is better than what' changes around in the 4 & 5 mm from what you are used to so you just have to look.
        .
        FM does not have a 10uF at all.
        KY and HE are close at about 1.35 [@/10kHz].
        Most other brand/series [and FC 10uF] are 1.80[@/10kHz] or more.
        .
        Last edited by PCBONEZ; 12-14-2010, 07:13 AM.
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          #5
          Re: GSC make crappy audio caps

          PCBONEZ - Thanks for the analysis. So, if I'm reading this correctly, you would have recommended using the 50V 10uF FC instead of the 25V I went with? Or something else entirely? Not that I plan on re-doing the repair, just trying to understand what you wrote and increase my knowledge a bit.

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            #6
            Re: GSC make crappy audio caps

            Originally posted by yyonline View Post
            PCBONEZ - Thanks for the analysis. So, if I'm reading this correctly, you would have recommended using the 50V 10uF FC instead of the 25V I went with? Or something else entirely? Not that I plan on re-doing the repair, just trying to understand what you wrote and increase my knowledge a bit.
            Yes if you want to optimize.
            The 25v will be WAY better than the GSC anyway though. - WAY WAY better!
            Mann-Made Global Warming.
            - We should be more concerned about the Intellectual Climate.
            -
            Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.
            - Dr Seuss
            -
            You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
            -

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              #7
              Re: GSC make crappy audio caps

              Originally posted by PCBONEZ View Post
              WAY WAY better!
              "Way way better" might be an understatement. Maybe 1/3 of the GSC didn't even register on the ESR meter. I figured they weren't making good contact with the meter as the leads seemed unusually thin and bent very easily. However, upon cracking a few open, they were bone dry inside. Not just the little 4mm ones, some of the 8mm and 10mm caps were all dried up as well. The box runs toasty, but not that toasty, and I only use it a few hours a day, so I wouldn't expect to see quality caps all dried up like that.

              I haven't worked with GSC much, and certainly not in such large quantities at once. I also found it sort of frightening how easily they crush. Even handling them gently with needle nose pliers seemed to result in denting the can. It seems they made them out of extra-thin and cheap metal. (Not that I'm surprised)

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                #8
                Re: GSC make crappy audio caps

                GSC make crappy capacitors full stop. I think their name stands for Garbage\Shit Capacitors.

                Pretty funny though if Klipsch was using them. I thought they were supposed to be pretty good?
                "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                -David VanHorn

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