I recapped some amps . And instead of 6,3 v I used caps having 50v .
Some mentioned that there is a risk of the cap to become defective because the cap would not receive enough current to maintain the forming process .
What do you guys think ?.
If I use the amp almost daily everything will be fine ?.
Or should I go to much lower v to be maximum double ?.
There is a safe limit or there is nothing to worry about if I use the amp regularly ?
Some mentioned that there is a risk of the cap to become defective because the cap would not receive enough current to maintain the forming process .
What do you guys think ?.
If I use the amp almost daily everything will be fine ?.
Or should I go to much lower v to be maximum double ?.
There is a safe limit or there is nothing to worry about if I use the amp regularly ?
Agreed, sort of. Depends on application but yes higher voltage caps will have other parameters that are different than the lower voltage caps. To be safe I wouldn't use them.
There is no problem regarding that because those are high end audio caps and are better compared to original .
My main worry is to not damage the caps because of less forming regarding the electrolyte oxide layer .
I'm just asking if a low voltage like 4v is enough to maintain a 50v cap formed
I was just thinking that maybe a 50v cap will need a minimum of let's say 12v or something.
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Interesting analysis. I have recycled a few 1970s vintage receivers and amplifiers over the last few years. I have a Kenwood KA3500 on my bench right now. Most of the caps in it test fine on a cap meter and the amp is functioning. I am going to measure the THD, noise etc and see if it meets specs. If I am replacing power supply caps I go one voltage range higher than the existing ones because line voltages here are higher now than they were in the 1970s and many of the caps are working near the voltage limit. For signal caps I stock good quality 50 and 63 volt that I use in all applications. Trying to match up every cap from 6.3v up would just be too many parts to stock. I’m not sure you can even get 6.3 volt caps these days.
It seems to me that any increase in ESR due to a higher voltage rating would not be an issue for coupling caps. Capacitance is usually rated at a 20% tolerance so any small change due to voltage rating seems negligible. As far as series inductance, we are talking about AC coupling of audio frequencies and my guess is that modern electrolytic caps are better in this regard then the 30 year old cap you are replacing.
I don’t really see much to worry about in using higher voltage rated caps in this application.
I’ve been repairing laboratory equipment for 35 years and in that time I have replaced countless electrolytic capacitors. Heat and over voltage are the 2 things that will do them in.
Let me explain again .
I don't think I explained good enough.
Someone stated that very high voltage caps should not be used if the oringinal cap voltage was very low.
He stated that if the cap is to big like 50v the cap "won't see the small 3 to 6v voltage" so will start degrading because the forming process will be disrupted or will not be maintained properly .
Personally I would not use an electrolytic capacitor that is rated at more than twice
the voltage that is seen in the circuit. You don't know what will happen to it, if not used
under intended operating conditions.
The audio grade caps are only a marketing concept, not/never clearly defined. Technically, a capacitor as well any other passive component is defined in the data sheets with the main important value (Resistance in resistors, inductance in inductors and capacitance in capacitors) and some secondary values (Insulation voltage(s), current(s) admissible, leakages, mechanic sizes, mounting drawings, etc.). But as all them have the others as parasitics (Inductors also have resistances and capacitances and so on), then, altering the main characteristics of the central value unfailingly will affect the other parameters with direct consequences in the performance in entire circuit, no matter the quality of the device be.
If in doubt, consult the datasheet and check for ESR. Up to a point, it is likely to decrease with capacitor size, but shape also plays a role. The effect of worse ESR at higher rated voltage generally refers to capacitors suitable for use on rectified mains voltage (or vacuum tube circuits), so generally >160 V. Chances are you weren't going to buy any of those anyway.
In terms of ripple current handling, basically bigger is better. It is determined by ESR and power dissipation (aside from temperature and endurance rating), the latter being a function almost entirely of physical size.
Not directly related, but be careful when using very low ESR capacitors in some positions, such as low-value coupling caps e.g. at pots. These may require low leakage caps, a requirement just about diametrally opposed to low ESR. Ultralow ESR caps can be downright conductive (leaving few applications besides bulk decoupling) and may be anything but particularly stable long-term. (Leakage is the flipside of the dielectric layer degrading.) As you might expect though, the same chemistry at a higher voltage rating will get you less leakage, due to the thicker dielectric.
These days a fair few series will achieve an official leakage rating of 0.001 CV, which would have been very good way back when, but one or two ultralow leakage series with a limited range of values are still available if you need them (generally for applications where long-term stability is required under conditions of no DC voltage across them and using two back-to-back is not an option).
In terms of ripple current handling, basically bigger is better. It is determined by ESR and power dissipation (aside from temperature and endurance rating), the latter being a function almost entirely of physical size.
Not directly related, but be careful when using very low ESR capacitors in some positions, such as low-value coupling caps e.g. at pots. These may require low leakage caps, a requirement just about diametrally opposed to low ESR. Ultralow ESR caps can be downright conductive (leaving few applications besides bulk decoupling) and may be anything but particularly stable long-term. (Leakage is the flipside of the dielectric layer degrading.) As you might expect though, the same chemistry at a higher voltage rating will get you less leakage, due to the thicker dielectric.
These days a fair few series will achieve an official leakage rating of 0.001 CV, which would have been very good way back when, but one or two ultralow leakage series with a limited range of values are still available if you need them (generally for applications where long-term stability is required under conditions of no DC voltage across them and using two back-to-back is not an option).
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Yea the only possible problem is if were to use them latter at a higher voltage.
Ripple current and impedance usually gets better as you go up in voltage see
1000u
P'sonic FM
V Irip imp 100k
10 1.79 0.026
16 2.47 0.019
25 2.60 0.018
35 3.19 0.015
50 3.32 0.016
R'con ZL
V Irip imp 100k
10 1.43 0.12
16 1.82 0.069
25 2.36 0.053
35 2.77 0.045
50 3.01 0.056
Ripple current and impedance usually gets better as you go up in voltage see
1000u
P'sonic FM
V Irip imp 100k
10 1.79 0.026
16 2.47 0.019
25 2.60 0.018
35 3.19 0.015
50 3.32 0.016
R'con ZL
V Irip imp 100k
10 1.43 0.12
16 1.82 0.069
25 2.36 0.053
35 2.77 0.045
50 3.01 0.056
How much of a variation is there in capacitance with voltage? My feeling is it can’t be large because when using a capacitance tester you do not have any way to compensate by specifying the voltage. Since the tolerance is normally +-20 % or higher the variation due to voltage may not be significant in most applications.
This has been already debated is not marketing besides the classical parameters there are other parameters regarding audio and that are different .
In the Classic Era, sometimes they used a 3-section 450V cap with one section bypassing a 15V cathode. It was said that the low-volt section always failed first. I don't know that any hard data was compiled.
In older e-caps, working capacitance and leakage might change with prolonged low voltage. Impurities in the aluminum and electrolyte made the film unstable. Today we know FAR more about electrolyte purity. The oxide should be "locked in", not subject to drift or decay for many years. (OTOH there has been a shift from old-time cap makers to low-cost cap making....)
In older e-caps, working capacitance and leakage might change with prolonged low voltage. Impurities in the aluminum and electrolyte made the film unstable. Today we know FAR more about electrolyte purity. The oxide should be "locked in", not subject to drift or decay for many years. (OTOH there has been a shift from old-time cap makers to low-cost cap making....)
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