I am interested in upgrading some audio components, and a lot of DIY tweak mention "replace the electrolytics in the signal path with Black Gate or other low-noise nonpolar capacitors." I know that polar capacitors cannot tolerate reversed polarity, and that bi-polars can as they are really two back-to-back capacitors. What is a non-polar? How is it different from a bipolar?
Dave
Ignore this silliness. A non-broken electrolytic capacitor is not noisy.
John
Well, it must be a non-polarized capacitor.
Polarized capacitors exist not because of function but because of manufacturing process.
There is no need for polarized capacitors.
But, in order to have higher value capacitors in reasonable sized packages, the manufacturers have to switch to methods that result in a polarized capacitor. The capacitor itself objects if the wrong polarity is applied.
For a lot of applications where higher value capacitors are required, that they are polarized doesn't matter, because they are mostly used where there is indeed a well defined DC voltage applied to one of the terminals. Thus, for filter capacitors in that power supply, a polarized capacitor doesn't matter because you connect the capacitor from a positive voltage to ground, so it's all very clear. A coupling capacitor on the output of an amplifier running off only a positive voltage has a positive voltage on that output, so again it's clear.
In a few cases, the capacitor won't actually see a clearly polarized voltage source. Crossover capacitors in speakers are a prime example, because the DC component has already been removed, either because the amplifier feeding the speaker has a DC coupling capacitor on the output, or has a transformer on the output (not likely in recent decades). Here, there is no longer an AC voltage riding on a DC voltage, so no matter what the AC voltage one side of the capacitor is clearly more positive than the other; there is an AC voltage coming into that capacitor, moving from positive to negative and back, in reference to the other side of the capacitor. You need a non-polarized capacitor there, but the issue of size and capacitance comes into play, and most capacitors of the values needed will be electrolytic. A common trick is to put two polarized capacitors in series, and sometimes they are manufactured that way, so the capacitor is not polarized.
But there are issues with that sort of scheme. For someone fussing with types of coupling capacitors in audio circuitry, they want non-polarized capacitors. Thus the capacitors need to be manufacturered using some scheme that will not inherently result in a polarized capacitor. If the values are low enough, this is not an issue. If the values of capacitance are higher, then one has to hunt around capacitors of mylar or polystyrene or some other scheme that does not result in a polarized capacitor, and the result may be a larger capacitor because those other formulations can't be so compact.
Michael
More audiophools?
Cheers
PeteS
Yup. You can send in your old Heathkit or Macintosh whatever tube amp to folks who will replace all the caps with Black Beauties or silver foil or whatevers, at huge expense.
John
Non-polar electrolytics are 2 polar elctrotytics back to back in a single case.
The validity of the benefit of black gate caps may be judged by the fact that they are no longer in production.
Many circuits will benefit simply by fitting a larger value electrolytic coupling cap when operated 'zero-biased'. The reason is sufficiently complicated for me to leave it out of here for now.
Caps don't make noise - so there's no such thing as a low noise capacitor.
Most audio nuts are simply blowing out of their arseholes.
Graham
Most pro-audio equipment uses large value coupling electrolytics in zero-bias conditions !
Ever wondered why ?
Graham
no different, In this case 2=0
Bye. Jasen
Pooh Bear wrote
In this context, I think they mean non-electrolytic non-polar capacitors.
Bob Pease of National Semiconductor and Electronic Design magazine has asserted that tantalum electrolytic capacitors may introduce audible distortion due to dielectric absorption effects (and he regularly mocks the Golden Ear crowd). He refers to this in his article "What's all this soakage stuff, anyhow?" which can be found at
I seem to recall an earlier article by him from the 1970s where he found that an amplifier with tantalum coupling capacitors sounded terrible, but it was fine after he replaced them with aluminum electrolytics. I can't find that article on the internet, and I am sure that I have thrown away that issue of the magazine.
If this argument is correct, then it might also apply to ceramic capacitors with high-k dielectrics.
-- That\'s not true. Just for single example, many ceramic caps with hi-k dielectrics are microphonic _and_ parametric.
About a decade ago, I got a catalog from a place here in Canada that did that sort of upgrade, and sold parts to do it yourself. I must have sent for the catalog thinking it might be a source of parts.
The catalog arrives, and the prices on the components were outrageous. I think the capacitors were going for a couple of dollars each.
Obviously, not a source for parts in Canada. And I still don't know if the parts they sold actually were expensive, or they just did a massive markup on them.
Michael
can send in your old Heathkit or Macintosh whatever tube amp
replace all the caps with Black Beauties or silver
expense.
Canada that did that sort of upgrade, and sold parts to do it yourself. I must have sent for the catalog thinking it might be a source of parts.
The catalog arrives, and the prices on the components were outrageous. I think the capacitors were going for a couple of dollars each.
Obviously, not a source for parts in Canada. And I still don't know if the parts they sold actually were expensive, or they just did a massive markup on them.
Michael
Probably so.
Before even considereing DA, hi-K and also medium-K ceramic caps produce measurable distortion and so shouldn't be used for signal coupling or feedback networks.
Graham
non-polarized
zero-bias
Large value coupling electrolytics where? In what type of audio equipment? Output stages? If there's no dc bias then they'd have to be nonpolars, no? I have read that larger-value coupling caps result in increased bass response... why is that? How are output coupling caps sized, I am guessing lowest-cost for "acceptable" performance. Can any coupling cap be replaced with one of a higher value?
Dave
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