I just built a preamp kit (Korg Nutube B1) where 10uF 25V polarized electrolytics were specified for input and output caps. Even though I used Nichicon FG's, I have enough space to plop film caps in there instead.
Assuming the holes in the board are big enough for the film cap lead diameters (big if), is there any reason why I can't swap in film caps for polarized electrolytics?
Assuming the holes in the board are big enough for the film cap lead diameters (big if), is there any reason why I can't swap in film caps for polarized electrolytics?
Looking at the board, I'd stick with electrolytics.
Film caps, being huge for that value, won't net any improvements.
Film caps, being huge for that value, won't net any improvements.
As long as you are planning to die or go deaf before 20 years.
I've had deterioration of sound with electrolytic input caps in 90's production products.
Film caps are 100 year parts.
And I've got equipment still up to spec from the 90's with original caps.
This "cap craze" is overblown long ago.
I've had plenty of 1990s gear needing caps, and plenty that does not. Most of it depends on how hot said device runs, and whether the caps are right next to heatsinks or power resistors.
There's also that equipment, like some of the early Tektronix TDS series scopes, that are notorious for defective caps (SMD electrolytics, in this case). So if you end up with a TDS380, take the time to recap it.
I like to use film caps instead of electrolytics whenever it's convenient. Lower ESL, lower ESR, better linearity (especially polypropylene) and they don't degrade over time the way electrolytic caps do. For small values, C0G ceramics are the way to go.
All of this goes out the window for HV caps, where mica, vacuum and paper-in-oil are still common and practical.
All of that said, you very likely won't notice any sonic difference at all with input coupling caps.
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I'm not saying electrolyics don't go bad over time, and I can agree with your statements.
However, you missed one area of importance.
That is WHO is the supplier?
And WHO was the designer?
In other words, when a certain product was manufactured, the person(s) in charge of ordering the parts/caps, as well as designing the layout chose a specific supplier.
And even some suppliers have sold "bad batches" on occasion...
That, of course, then contributes to a certain manufacturer's reputation, hurting the company, due to bad reviews, returns, and payout if under warranty.
Back in the 1990's, Mitsubishi large screen TVs (36" CRT screens) were flooding service shops like mine with defective 1uF caps throughout the set.
The main board had literally dozens, 50+ bad ones all over the place.
Whenever we got one in, we immediately knew the deal.
Some customers got irritated because the estimate to repair was high, not our fault.
Sometimes, yes.
The major reasons for electrolytic capacitors to deteriorate are:
Usage: The sustained use of the capacitor eventually degrades the dielectric layers inside the capacitor. The huge capacitance trades off for huge amounts of energy that cause damage.
Abuse: Close to heat, excessive ripple beyond spec, reverse voltage, etc
Electrolytic caps usually don't fail all that quickly. Really terrible caps in really terrible designs (or designs meant to not care about lifetime) will fail prematurely in terms of equipment life.
Even the normal service life of an electrolytic cap is worth it for its superior performance in some specific situations.
The major reasons for electrolytic capacitors to deteriorate are:
Usage: The sustained use of the capacitor eventually degrades the dielectric layers inside the capacitor. The huge capacitance trades off for huge amounts of energy that cause damage.
Abuse: Close to heat, excessive ripple beyond spec, reverse voltage, etc
Electrolytic caps usually don't fail all that quickly. Really terrible caps in really terrible designs (or designs meant to not care about lifetime) will fail prematurely in terms of equipment life.
Even the normal service life of an electrolytic cap is worth it for its superior performance in some specific situations.
Electrolytics degrade badly with time when there is little or no DC on them, definitely.
Those are designed for AC and last longer, but will still degrade over time.
Old speakers will usually need them to be replaced.
Old speakers will usually need them to be replaced.
It's usually up to the manufacuring of electrolytics, Quality Control, that plays a great part in their service life.
Strict Quality Control, and you have long-lasting products - I've seen many over the decades, caps, that are still within their tolerence design.
However, more recently, it seems that the QC isn't as good as back then, and this is besides that early/mid 2000's eruption with the "bad cap syndrome" that caused panic everywhere.
I believe that the current "change the caps!" craze was created from that, because I rarely saw anything on the "online blogs" about having to change them out.
Nor among my colleagues in the service business discussing them.
Oddly enough, around early 2000, the blogs were all flooded with the Cap Change Craze.
And I've serviced enough products both audio and video to justify my thoughts.
Strict Quality Control, and you have long-lasting products - I've seen many over the decades, caps, that are still within their tolerence design.
However, more recently, it seems that the QC isn't as good as back then, and this is besides that early/mid 2000's eruption with the "bad cap syndrome" that caused panic everywhere.
I believe that the current "change the caps!" craze was created from that, because I rarely saw anything on the "online blogs" about having to change them out.
Nor among my colleagues in the service business discussing them.
Oddly enough, around early 2000, the blogs were all flooded with the Cap Change Craze.
And I've serviced enough products both audio and video to justify my thoughts.
How long can one expect the high value Nichicon Muse coupling caps used in Doug Self's preamp to last?
There are ambient temperature etc. based charts about it.See the bad caps forums, there were many posts about bad capacitors, and fake capacitors.
Basically life depends on the service conditions, that means how stressed it is in terms of load and voltage, and also the continuous service temperature.
The makers also have life expectation on their sites, in terms of hours.
Basically if you have +/- 24 V rails, and put 50,63,or 100 V capacitors, the longest lived will be the 105 degree higher voltage slightly higher capacity ones.
Feel free to do a web search and satisfy your need for information...
Basically life depends on the service conditions, that means how stressed it is in terms of load and voltage, and also the continuous service temperature.
The makers also have life expectation on their sites, in terms of hours.
Basically if you have +/- 24 V rails, and put 50,63,or 100 V capacitors, the longest lived will be the 105 degree higher voltage slightly higher capacity ones.
Feel free to do a web search and satisfy your need for information...