Capacitance vs Temperature rating?

[A Jedi]

For PSU caps on an A/B amp, would it make more sense to go with bigger capacitance or higher temp rating (105C vs 85C) if you can't have both?

 

[rayma]

If all of the capacitance options are adequate, it mainly depends on whether
the amp has good ventilation and how often you want to service it.

If it has to be reliable for a long time, go with the 105C parts. For the best sound,
use more uF. In any event, buy a well known, quality brand from a reliable supplier.

 

[A Jedi]

Thanks.

 

[rayma]

Should mention that the DC voltage rating is also important for reliability.
Derate that as much as possible, but at least 20% from the rating.

 

[Bigun]

Be careful with temperature ratings, you need to check the lifetime too, sometimes you’ll see 105C for 1000 hrs and 85C for 5000 hrs. It can be the same cap, just has derated lifetime for the higher temperature.

 

[A Jedi]

Thanks guys.

 

[rayma]

Be careful with temperature ratings, you need to check the lifetime too, sometimes you’ll see 105C for 1000 hrs
and 85C for 5000 hrs. It can be the same cap, just has derated lifetime for the higher temperature.

Good point, don't fall for that stuff. Low ESR will increase the life also, due to less internal heating.
Roughly speaking, every 10C cooler gives twice the lifetime, whether environmental or self-induced.

 

[kodabmx]

Name brand doesn't matter as much as the quality/price point.

Nichicon make some garbage caps but they make excellent parts, too. It just depends on the price point and requirements.

Here is a life calculator from KEMET. Weblifecalc

I did one calculation of a KEMET part I use that's rated for 8000H@105°C... If it only gets up to 50°C, it'll last like 380000H!

KEMET make excellent parts as does EPCOS/TDK. SamYoung make a few lines of well made caps, too. as does YMin. Some are rated for Automotive (AEC-Q200). https://www.yminglobal.com/product/miniature_aluminum_electrolytic_capacitors

Just avoid buying crap caps from eBay. 🙂

 

[newvirus2008]

Yes, it's the actual operating core temperature of the capacitor that matters, not the temperature rating.

 

[asuslover]

In my PSU for A/B amps I do prefer the 105C capacitors.

Name brand doesn't matter as much as the quality/price point.

Nichicon make some garbage caps but they make excellent parts, too. It just depends on the price point and requirements.
🙂

Not sure how to calculate the quality/price ratio, the only thing I know here is the price ...... I think the brand is important because most of the time the brand dictates the quality.

Can you give examples pf those crappy Nichicons? Nichicon is one of my favorite brand and I would like to know not to buy/use any of those .
Thanks

 

[kodabmx]

This Nichicon UVY2G101MHD

(TL;DR 1000h@105°C, 100uF/400V 310mA ripple, 5,49$CAD)

compared to this Nichicon UCY2G101MHD6

(TL;DR 10000h@105°C, 100uF/400V 875mA ripple, AEC-200Q, 6,13$CAD)

Nothing wrong with the first part, but for an extra 64 cents, you get a massive upgrade.

Personally, I'm going with this Ymin LKMJ3552H101MF

(TL;DR 10000h@105°C, 100uF/500V 1.15A ripple, AEC-200Q, 2,38$CAD)

Koda