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confusion trading out some caps

First of all, I am a novice, so "thank you" in advance for your patience. I'm in the process of changing out some capacitors from the Xover of a budget-speaker. Instead of the common "uF" rating stamped on the cap, a "J" value is given for some. What does this stand for (a competent individual on another forum suggested "JOULE") and how do I formulate the "uF" value from this "J" value? I'd like to choose some replacement caps from the PEx catalog but cannot until I rectify this confusing situation. Thanks!
davesen
clueless
763 posts
 
A "J" tells you the tolerance rating for the cap, it stands for +/-5% of the given value.

Letter symbol Tolerance of capacitors:

B
+/- 0.10%

C
+/- 0.25%

D
+/- 0.5%

E
+/- 0.5%

F
+/- 1%

G
+/- 2%

H
+/- 3%

J
+/- 5%

K
+/- 10%

M
+/- 20%

N
+/- 0.05%

P
+100% ,-0%

Z
+80%, -20%


What are the other markings on the cap?

I remain,
davesen OP
4 posts
 
The other markings (well, the complete markings) read
"3.0J 100V" so, does that stand for a cap value of 3.0 uF +/- 5%? Seems logical, since some of the other caps have the common uF value and then actually read "+/- 5%" next to them. Why the inconsistency, I wonder? Different manufacturers, maybe?
clueless
763 posts
 
I think you've got it.
The thing is that there is no uniform system for marking caps and folks source them from all over.

Good luck. Swapping caps out of the xover can make a big diff. Generally a very good tweak.

Cheers
I remain,
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