Why do capacitors sound different?

on today's show we are going to talk about the endlessly fascinating subject of capacitors these tiny little miracle devices we use for power supplies and to pass audio signals our question today comes from Gerhardt in Calgary Canada hey Paul in your video about losing base because of impedance mismatches you mentioned using high quality capacitors what difference does the quality of an electronic component make in audio gear I assume cheaper parts might have less longevity but if they have the same specs what is technically different about them and how does it translate into audio quality in particular capacitors so let's let's talk about what is a capacitor so a capacitor is a device a component that will not pass battery voltage but it will pass audio voltage okay so what does that mean direct current direct voltage if you will what comes out of a battery well pretty much only pass through a wire and a capacitor is not a wire a capacitor is made up of interleaved pieces of insulators and conductors so in early capacitors we had like glass sheets so you had a you know a sheet of glass and then a which is an insulator you can't pass electricity through glass but other insulators are plastic paper air oil there's any number of substances that won't pass electricity and we call these insulators then we have conductors which is metals or chemicals that will pass electricity obviously copper aluminum tin all those steel they will all pass electricity so if a capacitor is made up of interleaved parts of insulators and conductors and we have them kind of sandwiched together and you can't pass a battery voltage through you put a battery on each end of the capacitor it it won't pass any current but put an audio signal through there and it will get through and that's because one is AC and it generates an electric field which will jump the barrier across that conductor that that insulator to the conductor and then again in pass it on through that so depending on the frequency how often the signal the voltage goes up and down which is our frequency it'll pass through the capacitor but if it's too low of a frequency or too close to being battery voltage then we don't have anything passing through so these are very valuable if you want to use it to block let's say we have a bunch of DC on the circuit and we want to block it we can pass the audio signal through it as you might through a gate but any DC voltage let's say at the output of a tube that might have 70 60 volts sitting on it it won't pass through it'll sit over here and won't get through that cap and that's kind of why we use those in an audio signal there also because they are selective on what frequencies they will permit the smaller the cap the the less that lower frequencies will pass through it we can use them for crossovers right so if you have a tweeter and you don't want any base frequencies you just take a small capacitor small and capacitance and hook it up to there because base frequencies which are closer to DC won't get through then no base notes get through to the tweeter and it only plays tweeter high frequency sounds does that make sense and if you want lower frequencies like for a mid range you men more capacitance and that then let lower frequencies through so here's here's two types of caps this one which is this kind of Oh inch inch in diameter well maybe half inch diameter and an inch tall cannister with two legs sticking out the bottom that's called an electrolytic and this is a fairly big capacitor one we would normally use in a power supply to store energy this is four thousand seven hundred microfarads micro farad's are the the way that we it's a was a thousandth of a farad and from Michael Faraday who had a lot to to long time ago with with teaching us how electricity works and we named the farad after Michael Faraday and this is a micro farad which is I think it's a thousandth of a fair add so this is four thousand seven hundred microfarads and this little guy which is about a quarter inch in diameter and maybe I don't know half inch tube half inch long tube with a conductor coming out of both ends oh just a wire is called a film capacitor so this one is made from very simply from a insulator in this case polypropylene which is a plastic and on top of that is layered a very thin sand a layer of copper foil and you take the the plastic film layer on top of it the foil and you just roll it up as you might a cigarette and then attach a wire at the beginning and the end of that roll and you have a film capacitor these are excellent for passing audio signals and this electrolytic well it has a lot of capacitance isn't as good sounding for audio purposes and that's to the heart of your question on here but look at the difference between the two this is four thousand seven hundred microfarads the this large whether it's this you know that's about the size of my thumb and this guy which is very small is considerably smaller in capacitance its point oh one five micro farad's because even if I could make this and we have film capacitors the size of this electrolytic they're very much smaller in terms of capacitance so an electrolytic SCID Vantage which uses a chemical inside for the for the called an electrolyte to manufacture it as opposed to hard materials the film and foil and this you can get huge amounts of capacitance at very low price this is probably 20 cents for this electrolytic and we get forty seven hundred microfarads this this this particular one is probably a dollar and it's point oh one five so very big difference in size and in cost and in purpose the electrolytic we use in power supplies the film cap because it sounds so much better we use in the signal path and the last part I'll tell you is in a budget sensitive product where we don't have I mean some of the some of the caps some of the film caps we use like in the BHK amplifier they cost us upwards of $20 apiece and the same capacitance in an electrolytic probably 15 20 cents so we can do a little nifty trick we can take a low ESR equivalent series resistance which is an excellent choice for an electrolytic if you're going to use an electrolytic in your signal path because of cost we can we can put one of those in and it'll sound pretty decent but then if we take one of these one of these film caps and we put it in parallel so let's say a 10 microfarad electrolytic with a tenth of of a micro farad film cap sandwiched together in parallel you get a pretty good decent sounding pass-through for audio signal and that's kind of one of the little tricks that we do when we voice a product and that just takes years of knowledge to figure all that stuff out all right so enough about caps away with you I'll talk to you tomorrow [Music] [Laughter] [Music]

Channel: PS Audio

Views: 266,083

Keywords: Ask Paul 1, Ask Paul 10

Id: mCk50RTtrT0

Length: 9min 24sec (564 seconds)

Published: Thu Mar 08 2018