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Effect of Film dielectric type on capacitor ESR

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  • Effect of Film dielectric type on capacitor ESR

    Detail performance tests were run on four ERSE capacitors to look at the effect of dielectric on ESR. Two 2.0 uF and two 3.9 (4.0) caps were tested. Each group had a polypropylene dielectric (Pulse-X brand with black color & gold printing) and a Polyester dielectric (yellow color with black printing).

    What I found with these two levels of capacitance was a significant difference in ESR between the dielectrics in the 100 to 10000 hz range with PET generally trending higher in the freq. range evaluated. Below is a plot of the data derived from WT2 test data.

    IMO, the polyester ESR performance approaches that of an electrolytic. This may be of some value to those recapping that don't want to alter the voicing of the speaker or, where a slightly reduced response is needed in a particular frequency range.

    The link below gives a good explanation of why ESR is different between the dielectrics.
    http://www.cartage.org.lb/en/themes/...iderations.htm
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    Last edited by carlspeak; 08-13-2012, 07:03 AM.
    Live in Southern N.E.? check out the CT Audio Society web site.

  • #2
    Re: Effect of Film dielectric type on capacitor ESR

    Thanks.
    "He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche

    http://www.diy-ny.com/

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    • #3
      Re: Effect of Film dielectric type on capacitor ESR

      Originally posted by carlspeak View Post
      Detail performance tests were run on four ERSE capacitors to look at the effect of dielectric on ESR. Two 2.0 uF and two 3.9 (4.0) caps were tested. Each group had a polypropylene dielectric (Pulse-X brand with black color & gold printing) and a Polyester dielectric (yellow color with black printing).

      What I found with these two levels of capacitance was a significant difference in ESR between the dielectrics in the 100 to 10000 hz range with PET generally trending higher in the freq. range evaluated. Below is a plot of the data obtained with a WT2.

      IMO, the polyester ESR performance approaches that of an electrolytic. This may be of some value to those recapping that don't want to alter the voicing of the speaker or, where a slightly reduced response is needed in a particular frequency range.

      The link below gives a good explanation of why ESR is different between the dielectrics.
      http://www.cartage.org.lb/en/themes/...iderations.htm
      The dielectric has little (i.e. practically no effect) on the ESR, which is the equivalent series resistance of a capacitor. The thickness of the metalization or foil and the method of connection of the leads to metal plates of the capacitor are usually the dominant factors. Metalized aluminum is very difficult to solder to and many foil caps use tin, copper, or even silver foil for the ease of soldering and getting the lowest ESR. Teflon caps usually have low ESR since the use foil since teflon cannot metalized like mylar, polycarbonate, and polypropylene caps usually are. Film and foil caps are bigger and more expensive and used where large peak currents are involved. A lot of the German capactor companies have good articles on this stuff on there web sites. This is one the reasons it is good to parallel capacitors in crossovers is that the ESRs drop by being restances in parallel. I really think film caps under about 10 uf sound better than say a 30 uF cap and would parallel 3 10 ufs before using a 30uF cap.

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      • #4
        Re: Effect of Film dielectric type on capacitor ESR

        Originally posted by fdieck View Post
        The dielectric has little (i.e. practically no effect) on the ESR, which is the equivalent series resistance of a capacitor. The thickness of the metalization or foil and the method of connection of the leads to metal plates of the capacitor are usually the dominant factors. Metalized aluminum is very difficult to solder to and many foil caps use tin, copper, or even silver foil for the ease of soldering and getting the lowest ESR. Teflon caps usually have low ESR since the use foil since teflon cannot metalized like mylar, polycarbonate, and polypropylene caps usually are. Film and foil caps are bigger and more expensive and used where large peak currents are involved. A lot of the German capactor companies have good articles on this stuff on there web sites. This is one the reasons it is good to parallel capacitors in crossovers is that the ESRs drop by being restances in parallel. I really think film caps under about 10 uf sound better than say a 30 uF cap and would parallel 3 10 ufs before using a 30uF cap.
        I didn't make this stuff up. Here is a quote from the link I provided. "For low capacitance values, the inherent dissipation factor of the dielectric material contributes most significantly to ESR." Now, we could get into the semantics of how low is low, but I think the ref. material spells out that there are a number of factors with ESR also varying depending on the nominal uF value. What I tried to show was how capacitors from the same manufacturer with different dielectrics are different.
        Live in Southern N.E.? check out the CT Audio Society web site.

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        • #5
          Re: Effect of Film dielectric type on capacitor ESR

          First off Carl, Thanks for the great work and practice as always.

          I am not surprised by the results. Reading technical articles, heck a degree in Electrical Engineering does not often replace people's specialized life works on the effects that take place in passive components, though a lot of "great minds" can draw conclusions off enough web information to be dangerous. I had no appreciation for this until I started working for a company that specializes in resistors for specialty applications, and once I got reading and learning the differences are amazing. Even at the frequencies in which audio occurs that people often ignore because they are not microwave, the parasitic effects, environmental effects, even the effects caused by the component itself on itself are astounding. And we a talking about silly little resistors here, you now the least important bastard child of audio. The "easiest" component if you will.

          That said and thinking practical application: Does it make sense to use polester caps on a tweeter, with increased ESR at low frequencies, not only is it rolling off LF information, but attiunating it as well? Complete theory/conclusion drawn here, but it *could* lower THD of the driver since the driver will not be seeing as much information 20dB down or so, making the caps makes a difference argument very valid in the build type catagory (which we already know a little since electrolytics are the root of all evil)... Or, it occurs so little so low it makes no difference. I still think it was a great test.
          Facebook Page - Ocean State Acoustics

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          • #6
            Re: Effect of Film dielectric type on capacitor ESR

            Originally posted by carlspeak View Post
            I didn't make this stuff up. Here is a quote from the link I provided. "For low capacitance values, the inherent dissipation factor of the dielectric material contributes most significantly to ESR." Now, we could get into the semantics of how low is low, but I think the ref. material spells out that there are a number of factors with ESR also varying depending on the nominal uF value. What I tried to show was how capacitors from the same manufacturer with different dielectrics are different.
            I can only tell you what my experiences are with 25 years of playing with audio grade capacitors and reading dozens of technical articles from capacitor manufacturers. My best results with crossovers has been with polystyrene or polpropylene and foil caps from Rel Cap. The foil caps from ERO, Seimens, and Philips are also very good.

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            • #7
              Re: Effect of Film dielectric type on capacitor ESR

              I almost am afraid to mention the really strange stuff I have messed with in passive components. The first Vishay resistor samples I got (1987) were from the Dallas rep who was very curious why I wanted them since he usualy delt with people like NASA and Rockwell. I have some suplus 0.5 ohm resistors in TO-3 transistor cases that I found out were 40 bucks a piece new. Did you know film caps in a speaker sound different with a DC bias on them or that the value of capacitances changes slightly with changing pressure. Wonder if external crossovers away from the vibration and changing pressures inside a speaker are overkill? And yes lead free silver content solder does sound better

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              • #8
                Re: Effect of Film dielectric type on capacitor ESR

                Others swear by the silver foil and PCB oil Russian audio capacitors still available. I don't know exactly what that means either, except that's what some people want to buy. Do they sound "better"? Who knows? Do they sound different? Probably. Are they hard to get and expensive? Absolutely.

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                • #9
                  Re: Effect of Film dielectric type on capacitor ESR

                  Originally posted by fdieck View Post
                  My best results with crossovers has been with polystyrene or polpropylene and foil caps from Rel Cap. The foil caps from ERO, Seimens, and Philips are also very good.
                  I like my MultiCaps PPMFX (Rel), and also agree that they're VERY nice. I've also used the MKC ERO's, and like them. You should try the ASC in Oil if you haven't.

                  Later,
                  Wolf
                  "Wolf, you shall now be known as "King of the Zip ties." -Pete00t
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                  • #10
                    Re: Effect of Film dielectric type on capacitor ESR

                    I just wonder at what point are we "gilding the lily"? Or better as I can relate to, people putting racing spark plugs in a street grocery getter. It costs alot more, you can impress you friends, they won't last 1/10th as long, and they don't work as well but they're RACE PLUGS. Is a $50 capacitor(s) going to make a real difference in the sound of a $300 DIY pair of MT (or even $600 3-way) speakers?

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                    • #11
                      Re: Effect of Film dielectric type on capacitor ESR

                      Originally posted by Whitneyville1 View Post
                      I just wonder at what point are we "gilding the lily"? Or better as I can relate to, people putting racing spark plugs in a street grocery getter. It costs alot more, you can impress you friends, they won't last 1/10th as long, and they don't work as well but they're RACE PLUGS. Is a $50 capacitor(s) going to make a real difference in the sound of a $300 DIY pair of MT (or even $600 3-way) speakers?
                      If it is the right cap..... unfortunately yes. I have recapped and rewired many hi end speakers and have always been surprised at the difference. Magnapan MG III, Thiel CS 3.0, Infinity RS1b and many less expensive speakers have benefited greatly. The level of quality of even a 10 to 30 dollar Vifa driver is good enough now to reveal caps and wire types in a good system. It does not take 50 bucks to get a good cap.

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                      • #12
                        Re: Effect of Film dielectric type on capacitor ESR

                        Originally posted by fdieck View Post
                        I almost am afraid to mention the really strange stuff I have messed with in passive components. The first Vishay resistor samples I got (1987) were from the Dallas rep who was very curious why I wanted them since he usualy delt with people like NASA and Rockwell. I have some suplus 0.5 ohm resistors in TO-3 transistor cases that I found out were 40 bucks a piece new. Did you know film caps in a speaker sound different with a DC bias on them or that the value of capacitances changes slightly with changing pressure. Wonder if external crossovers away from the vibration and changing pressures inside a speaker are overkill? And yes lead free silver content solder does sound better:headphones:
                        Speaking strictly from conversations with application engineers who put our products in satellites, there is good reason and it boils down to the metallurgy. The key is if copper exists in the lead of the component and you use a lead-free solder with copper content you end up avoiding the capacitive and thermal effects, as well as effects on transconduntance through the joint. Plus, let's not forget there are two Joints per cap. Better? Who knows....However it is probable it makes a difference and in theory negative effects are ultimately lowered.
                        Facebook Page - Ocean State Acoustics

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                        • #13
                          Re: Effect of Film dielectric type on capacitor ESR

                          Mike: Ask your app. engr's if any iron content in copper wire can become magnetized over long periods of heavy use.
                          Live in Southern N.E.? check out the CT Audio Society web site.

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                          • #14
                            Re: Effect of Film dielectric type on capacitor ESR

                            I will see him tomorrow... Weird Rhode Island holiday today. He has mentioned purity and concern over the effects of dissimilar metals causing electrolysis and ultimately long term failure due to different conductive abilities. He's a cool guy... Since I starting having lunchtime conversation with him around audio caps and the war raging he has taken an interest. He is from Isreal and spent his career studying conductance and metallurgy.

                            As you can tell I am no longer at Pepsi. I work at Vishay EFI (that GAWD I am back in the electronics industry) and our division specializes in thin film, high precision micro resistors, conductive plates, and resistor/plate combinations. Every day I go in I feel like I am a land of giants... One of my welcome gifts was a 300 page textbook written by Felix Zandman (founder of Vishay in the 60's) on resistive theory. Oy!
                            Facebook Page - Ocean State Acoustics

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                            • #15
                              Re: Effect of Film dielectric type on capacitor ESR

                              Congrats on the Vishay employ!

                              I should add to my magnetization question of ferous content of non-pure copper wire, cap and resistor leads which are highly ferrous.

                              Oy, now I've taken my own thread OT! BUT, for good reason.....
                              Last edited by carlspeak; 08-13-2012, 10:21 AM. Reason: confession
                              Live in Southern N.E.? check out the CT Audio Society web site.

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