Accuton tweeter crossover to Focal Kevlar midrange, so not huge values. Solen made around 1990, not premium exotic, probably polypropylene. Presently covered in a layer of dust (which I will remove in a clean up soon as the speakers are put back into service in my listening room).
That is why you are not getting precise values and materials from me in this post. Cases are intact, still hard as rock, and leads to cap body not compromised by corrosion.
So, any firm measurements or "reasonable conjectures" on drift over 25 years? I would guess that cap manufacturers have hard data, but they likely do not release it to us unless it is unfavorable to competitors !
As always, TY in advance . . .
That is why you are not getting precise values and materials from me in this post. Cases are intact, still hard as rock, and leads to cap body not compromised by corrosion.
So, any firm measurements or "reasonable conjectures" on drift over 25 years? I would guess that cap manufacturers have hard data, but they likely do not release it to us unless it is unfavorable to competitors !
As always, TY in advance . . .
I haven't seen this happen in smaller caps, but I suppose it's possible in high current crossover caps.
Imperfect sealing can let moisture in, but this is usually only a problem with paper caps. Unlikely that a plastic film cap will drift with age.
Film caps made by global, reputable manufacturers like Wima, LCC, Siemens (now Epcos), etc are rock stable provided they aren't stressed: metallized ones can be damaged by extreme currents (brutal short-circuits) and voltage surges:
X-caps typically loose a few percents a year under normal operating conditions.
Foil caps cannot degrade: when they are over-stressed, they fail in short-circuit.
In a crossover, the conditions are pretty easy for a capacitor, even if you listen at extreme levels all day long: the drivers will most likely fail well before the caps.
For "audiophile" capacitors, I wouldn't be that categorical (and Solen falls more or less into that category): smaller manufacturers do not have access to advanced quality control techniques that really huge houses can afford.
The smallest amount of impurity, moisture or air ingress in any of the constituents can lead to a slow degradation that will only appear after tens of years, and it will generally not show in the raw capacitance figure, but in the tan δ for example.
X-caps typically loose a few percents a year under normal operating conditions.
Foil caps cannot degrade: when they are over-stressed, they fail in short-circuit.
In a crossover, the conditions are pretty easy for a capacitor, even if you listen at extreme levels all day long: the drivers will most likely fail well before the caps.
For "audiophile" capacitors, I wouldn't be that categorical (and Solen falls more or less into that category): smaller manufacturers do not have access to advanced quality control techniques that really huge houses can afford.
The smallest amount of impurity, moisture or air ingress in any of the constituents can lead to a slow degradation that will only appear after tens of years, and it will generally not show in the raw capacitance figure, but in the tan δ for example.
TY, Bwana.
(Cefem industries in France, owns SCR, manufacturer of the Solen caps. >20/<50 employees)
(Cefem industries in France, owns SCR, manufacturer of the Solen caps. >20/<50 employees)
From a global perspective, yes, especially considering that in their case they are selling high added value items.
That said, the fact that they managed to keep their reputation intact for some decades (apparently) speaks in their favor.
Having a clientele relying on their ears rather than hard quality-control tests may also help a little in this respect: when a power supply manufacturer prepares to buy a million pre-PFC bypass caps from ERO for example, he may not be content with just the good looks of the capacitor, or the website, or the opinions of forum members...
An error at this level can be very, very costly
Original poster here --- Thanks to all who threw their 2 cents into this pickle barrel. I will bail out of further remarks, but will read any additional replies.
Most capacitors are usually good with age unless over voltage is applied.
I usually find its electrolytics that don't last forever.
On old amps I always replace all the electrolytics regardless.
Sometimes spec on electrolytics can be as little as a couple of thousand hours.
I usually find its electrolytics that don't last forever.
On old amps I always replace all the electrolytics regardless.
Sometimes spec on electrolytics can be as little as a couple of thousand hours.
The real question is/was what the required volume and/or annual revenue would have be, to be a reputable manufacturer, in a global perspective ?
(very surprised to see a $6 million total, would have expected it be a lot higher)
Anything with a liquid electrolyte can age. This includes paper in oils,especially those that use vegetable oils.
Plastic films are stable unless the metal layer corrodes
Plastic films are stable unless the metal layer corrodes
If I remember correctly, some Solen caps had zinc metallization instead of aluminum. This might corrode and change capacitor value if there is moisture ingress over the years. I've never seen an aluminum metallized film cap drift with time.
I had hundreds of Solens from the mid 80's to 2014 in my parts bin and all the caps with date codes from the early 90's with black ends ( not original red or later gray ) epoxy fill were off value all low by 10 to 30 % and falling lower with time - I discarded them as unreliable. Others on Diyaudio reported the same problem maybe a decade ago with the black ended Solens from the early 90's. So yes some manufacturing defect occurred in that series of Solens, the other Solens in my box even 30 years old still meet their labeled value
Yes, but it still has a dielectric constant. Oxidation and evapouration both shift the capacitance and risk electrical breakdown.
Mineral oils have Er of ~2.5, vegetable oils Er in the 3 to 5 range
The self healing action of a metallized film will cause a small area of the deposited aluminum to 'disappear' as the short is cleared / burned out. So, if a cap is run into breakdown with some regularity, I could imagine it 'drifting' down in value over time. But drift while never being installed has to be some sort of schoopage / metallization chemical degradation.
why get opinions, "firm" or otherwise , 1st clean it then identify the part number, & just measure it! capacitance is the easiest thing to measure of all other things bout a cap like ESR or dV/dt ratings.
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