Replacing all capacitors with solid polymer ones inside amplifier

Robert2017

Robert2017

Active Member
Is this a good ideea ?. To replace all wet capacitors with solid polymer ones ?.
There are some benefits or side effects ?.
I noticed that solid polymer ones are more expansive .
One 100uF; 50VDC polymer cost 2 $
One 100uF; 50VDC Nichicon KZ audio cap costs 0.39 $ and SILMIC 2 costing 1$ or less
Usually those appear to be tantalum-polymer or simply polymer .
 
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Anything bigger than 10uf tends to get big fast.
Old tantalums had issues. I've heard new onew are better but really no 1st hand experience.
 
Robert2017 said:
Is this a good ideea ?. To replace all wet capacitors with solid polymer ones ?. ...
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Yes, no, maybe.:confused: It all depends on the circuit useage, and what characteristics are most important for the purpose.

Solid polymer electrolytics are much better than wet electrolytics in most characteristics:

Much lower ESR (tho not necessarily a good thing) & ESL
Much higher ripple current handling
Better temperature & bias coefficients
Longer life, reliability & stability
etc.

... but they fail miserably in one respect: much higher leakage current (5-10x as much).

So, ... it just depends.

The best are Hybrid Polymers: combines solid polymer with a little bit of "wet", to bring the leakage back down to normal levels while keeping all the better solid characteristics.

Unfortunately, the vast majority of these are only available in surface mount packages, and the few thru-hole that are out there are very limited in size choices.
 
Robert2017 said:
Is this a good ideea ?
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It's an interesting idea, Solid Polymer are certainly different to wet electrolytics - whether they are better for audio use I have no idea. The above post seems to have summed it up nicely, the leakage issue alone would be enough to put me off, followed by the size choice, and lack of through hole availability mentioned. I also have an idea that their voltage ratings would tend to be on the low side, because of what I believe is their main use - namely, in computers.

'Replacing all' would be a bad idea, but there could be some locations in audio gear where they might be advantageous.
 
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Aren't poly caps mostly just WAY too big for use in the confines of an amp? In a crossover then sure, where space isn't really a concern I suppose. Small ones in the signal path, maybe.
 
Markoneswift said:
Aren't poly caps mostly just WAY too big for use in the confines of an amp? In a crossover then sure, where space isn't really a concern I suppose. Small ones in the signal path, maybe.
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The suggestion here is to use solid polymer (rather than wet electrolyte) electrolytics, not polymer film (which tend to be physically large). Polymer electrolytics are physically roughly the same size of equivalent "wet" electrolytics, but limited sizes and form factors are available.
 
No, not Polystyrene, Polypropylene or Polyester, - but 'Solid Polymer' - different thing. You can see them on computer motherboards in their dozens - looking like small electrolytic capacitors - often with no plastic sleeve.
 
Yes I was speaking about Polymer electrolytics physically roughly the same size of equivalent "wet" electrolytics,

There 's no way in lowering the leakage current ?. Like for example bypassing with some Vishay 0,1uf teflon or something ?

I was thinking there should be a better alternative to wet electrolytics.
 
Robert2017 said:
Yes I was speaking about Polymer electrolytics physically roughly the same size of equivalent "wet" electrolytics,

There 's no way in lowering the leakage current ?. Like for example bypassing with some Vishay 0,1uf teflon or something ?

I was thinking there should be a better alternative to wet electrolytics.
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Bypassing with film has nothing to do with leakage current. You're worrying too much about the effects of caps when there are many other factors to consider.
 
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Robert2017 said:
I was thinking there should be a better alternative to wet electrolytics.
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Maybe someone will find one, but for the purposes where wet electrolytics are currently used, they are almost invariably the best compromise in terms of physical size, cost, longevity, leakage, ESR, ESL, etc. Sometimes, say, a poly film cap may be a better choice for certain audio applications, but that means greater expense and physical size.
 
Robert2017 said:
... I was thinking there should be a better alternative to wet electrolytics.
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As I said before, the best alternatives are Hybrid Polymers.

They retain all of the best characteristics of solid polymers, AND the lower leakage of wet electrolytics.
  • Solid Polymers are quite limited in size & voltage range relative to wet electros, but ARE readily available in thru-hole.
  • Hybrid Polymers are even more limited than Solids, and NOT readily available in thru-hole.
I wanted to use some in recent projects but was thwarted by the limitations:
  • Wanted 1000uF/35v (leakage irrelevant), but highest voltage available is 16v, so no-joy.
  • Wanted 10uF/35v (lower-leakage), but smallest thru-hole Hybrid is 33uF, so no-joy.
Perhaps with time manufacturers will produce a wider range, but I don't hold out hope.

So, if high-leakage is not a concern in your application, Solid Polymers are great!
... and/or
if super low ESR is not detrimental to your application, Solid Polymers are great!

Then, if high leakage IS a concern, AND you can find your size/voltage in a thru-hole (or SMD if you can solder those), then Hybrid Polymers are great!
 
HalfApt said:
As I said before, the best alternatives are Hybrid Polymers.

They retain all of the best characteristics of solid polymers, AND the lower leakage of wet electrolytics.
  • Solid Polymers are quite limited in size & voltage range relative to wet electros, but ARE readily available in thru-hole.
  • Hybrid Polymers are even more limited than Solids, and NOT readily available in thru-hole.
I wanted to use some in recent projects but was thwarted by the limitations:
  • Wanted 1000uF/35v (leakage irrelevant), but highest voltage available is 16v, so no-joy.
  • Wanted 10uF/35v (lower-leakage), but smallest thru-hole Hybrid is 33uF, so no-joy.
Perhaps with time manufacturers will produce a wider range, but I don't hold out hope.

So, if high-leakage is not a concern in your application, Solid Polymers are great!
... and/or
if super low ESR is not detrimental to your application, Solid Polymers are great!

Then, if high leakage IS a concern, AND you can find your size/voltage in a thru-hole (or SMD if you can solder those), then Hybrid Polymers are great!
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Are you reffering to Aluminium Organic Polymer Capacitors like for example
Panasonic EEH-ZE Hybrid Aluminum Electrolytic Capacitors ?
It appears those don't have leads but maybe some leads can be soldered in order to addapt for amplifiers ?.
What do you think ?
 
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Robert2017 said:
Are you reffering to Aluminium Organic Polymer Capacitors like for example
Panasonic EEH-ZE Hybrid Aluminum Electrolytic Capacitors ?
It appears those don't have leads but maybe some leads can be soldered in order to addapt for amplifiers ?.
What do you think ?
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Well, yes and no. Those are the surface mount types I'm referring to, but they're only available from 33 to 300uF. No 10uF, no 1000uF.

Panasonics ZF series is the same cap in thru hole, but harder to find anywhere in-stock.

Even if the needed sizes were available in SMD, hacking them to fit a thru-hole isn't worth the effort IMO.
 
what will happen if I take an amp and replace all wet caps with hybrid polymers (excluding psu big ones)
Should I exect OPamps or some transistors to oscilate or blown ?
 
Robert2017 said:
what will happen if I take an amp and replace all wet caps with hybrid polymers (excluding psu big ones)
Should I exect OPamps or some transistors to oscilate or blown ?
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If the capacity values are within the tolerance range of the originals, it should work fine.
 
Hyperion said:
No, not Polystyrene, Polypropylene or Polyester, - but 'Solid Polymer' - different thing. You can see them on computer motherboards in their dozens - looking like small electrolytic capacitors - often with no plastic sleeve.
Click to expand...

Ah, I was thinking of some metalized polypropylene caps I bought recently. They got large and expensive quite quickly !
 
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