Is it really bad to use electrolytic capacitor for 0VDC + AC signal?
I heard electrolytic capacitors are polarized and thus should be used where the recommended polarity is maintained (e.g., dc power supply ripple filter, etc.)
I am asking this because I saw a schematic where polarized electrolytic capacitor is used for line level audio input and output coupling. The active components are OP amps running with + dc power supply and - dc power supply, hence there is no DC-shift-up as in single ended A-class amp.
I heard electrolytic capacitors are polarized and thus should be used where the recommended polarity is maintained (e.g., dc power supply ripple filter, etc.)
I am asking this because I saw a schematic where polarized electrolytic capacitor is used for line level audio input and output coupling. The active components are OP amps running with + dc power supply and - dc power supply, hence there is no DC-shift-up as in single ended A-class amp.
Yes, it's bad. Worse yet, the electrolytic cap will likely have an optimum bias voltage.
Search this forum for "Bateman capacitors" for links to a fairly exhaustive study of cap types and the distortion they create.
Search this forum for "Bateman capacitors" for links to a fairly exhaustive study of cap types and the distortion they create.
Non-polar electrolytics exist for applications where no bias is present (like passive speaker XOs).
It looks like this. I do not understand how polarized 10uF capacitors can be used at the input and output. This product has been sold world wide for much more than 10 years.
That circuit is fine with polarised caps. I would recommend though that polarity be determined by measurement of the actual voltage across the cap in situ. It will be millivolts or less but may as well have it right as not.
No problem with the configuration or cap type though.
No problem with the configuration or cap type though.
With no DC bias the cap might slowly, over many decades, lose its ability to support its full DC voltage rating, but there isn't really a problem with zero voltage. Tantalums are a special case. With even 10 mV or so of reverse bias, over many years, the DC leakage will permanently go up.
I need to reread Bateman, but I don't think adding a bias accomplished much in terms of distortion.
Remember that, other than filters, caps should be large enough that no audio voltage appears across them.
I need to reread Bateman, but I don't think adding a bias accomplished much in terms of distortion.
Remember that, other than filters, caps should be large enough that no audio voltage appears across them.
If they are on audio signal path, I would recommend putting BP instead for better linearity and less distortion.
Two Nichicon ES in opposing "polarity", parallel, work well (you have to use double the value on each, like parallel resistors mathematically, but for uf value to equal original corner frequency). The only good option for a single one is Blackgate N, which are no longer made.
This retains the bass and treble. Also it's as transparent as you'll want.
I had been going through it again so it was fresh on my mind. From Part 6:
"With no bias voltage, the capacitor produced predominantly second harmonic distortion. In some instances, application of a very small optimum DC bias did minimise this second harmonic. Increased bias however resulted in increased second harmonic distortion."
But this is all FYI. I'm not a chase-audio-ideals-all-the-time person. For size and cost the 10uF 'lytic is fine by me.
Nichicon ES are bipolar electrolytic capacitors. Unless I misunderstood your post, how would you put them in opposing polarity and why? When replacing the polar capacitors with bipolar ones, the values are 1:1, as far as my experience goes.
They are bi-polar but depending on orientation you'll get different sound. This is true for Blackgate N as well (note: Peter Daniels prefers reverse orientation).
When you buy them they still have one longer lead (positive). If you look inside you'll notice that one lead is inside, another outside.
When you replace one capacitor with two you have to compensate for the difference by doubling the value of both capacitors used, starting with the original value of one capacitor. If you do not you'll shift the corner frequency.
An externally hosted image should be here but it was not working when we last tested it.
There are my DC voltage measurement on the four supposedly polar caps. The output caps are nichicon polar electrolytic caps. It has black case with gray stripe on the - side.
Input left: -5.7mV
Input right: -5.4mV
Output left: +1.9mV
Output right: +1.4mV
The input caps are polar on the schematic, but on the actual product they do not look like polar caps. They have blue rectangular case and 47nJ63 is written on the case.
Input left: -5.7mV
Input right: -5.4mV
Output left: +1.9mV
Output right: +1.4mV
The input caps are polar on the schematic, but on the actual product they do not look like polar caps. They have blue rectangular case and 47nJ63 is written on the case.
Hi,
Now I'm confused...😕
When you put two caps in parallel the capacitance is increased so two identical caps would give twice the capacitance. Your reasoning is for caps in series. So the two caps should be half the capacitance of the otiginal cap so the total remains the same. Right?
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Yes, but you've halfed the ESR/ESL.
I wanted to find an old lengthy post here on DIYaudio all about input capacitors including multiples.
I wanted to find an old lengthy post here on DIYaudio all about input capacitors including multiples.
Yes, leads are indeed uneven like on polarized caps. But I find no theoretical explanation for your claim, as both electrodes are chemically treated the same, nor do I find any manufacturer's instruction to support it. But if this is true, then I hate you because I have at least 30 of ES' in my system, arbitrarily turned and soldered in all orientations.
I have been using electrolytic's on audio for around 40 years and never seen any problems.
There are literally thousands of designs using them in audio applications.
There are literally thousands of designs using them in audio applications.
I have a NFB capacitor. This capacitor is audible. You're saying that if I get two Muse ES and connect them anti-parallel I get and "invisible" cap, as good as DC coupling?
back to back capacitors are normal in signal pass for long time...just recapped old NIKKO preamp...great sounding now
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