Capacitors for Class A - large can type vs small snap in

Like for like in values its down to the amount of reduction in ripple current.


Larger (like for like ) capacitors have the potential for greater storage and hence longer term stability under heavy load.

I have some older class A amps that was someone’s diy project and they are now mine
They have the very large blue caps in them
So if I understand you right. It is OK to replace them with smaller caps with the same or high value?

duncan2 said:

Larger (like for like ) capacitors have the potential for greater storage and hence longer term stability under heavy load.

Click to expand...

Please explain what is "greater storage" and how a larger capacitor of the same exact specifications has more of this mysterious "storage" than a physically smaller one.

Capacitors have capacitance, voltage rating, equivalent series resistance, inductance, ripple factor at a known test frequency. If one knew all of these specifications, he could predict if a product of a different type could replace another product. Mostly these numbers aren't known of an old product, and many are not published for new products.
I've successfully replaced large can caps of the 70's & 80's with a physically smaller snap in cap, or an array of smaller snap in caps wired in parallel with suitable (18 ga or 16 ga) wire. Success is not guarenteed. I've used NEMA CE composite board to glue the caps to for arrays, then screw the board to the chassis with standoffs.

Generally, I find the larger caps usually handle higher ripple current and have a longer lifetime than the smaller versions. Not a rule, of course.

My point is that physical volume is NOT an electronic attribute. Everything electronic being the same, 2 capacitors of different sizes will behave exactly the same. The only possible difference may be heat dissipation, which is related to skin area. But if a capacitor needs to dissipate that much heat, you have more important problems than size...

Osborn said:

I didn't see this specific topic (sell one sort of).
I'm look at the same values uf, voltage, temp and what not in large can type and smaller snap in type. Given all values are the same, do the larger caps offer better performance to rid noise from the power supply? Thanks much.

Click to expand...

Fact is they aren't , this is why you have big ones and small ones

if you want do get rid of the noise , size doesn't matter , math matter

PSUD2 helps you to make those math

.

fabrice63 said:

Fact is they aren't , this is why you have big ones and small ones

Click to expand...

Not necessarily. One manufacturer may come out with a new product, using newer materials and techniques. That may allow it to make a smaller cap with the same electrical characteristics as an older, bigger design.

Be careful about adding large amounts of C to a power supply. Diodes & xfmrs will suffer if you overdo it.