When to replace caps in speakers?

[maindude]

Hi Everyone,
I'm a newbie here, so please be gentle. I have a pair of Klipsch KG2's, which I bought second hand, built in 1989. In each crossover there are 3 caps, one electrolytic, and 2 metalized polypropylene caps. Would it be worthwhile to
1)replace all the caps,
2)just the electrolytic,
3)or none at all.
Does the material of the cap effect it's lifespan? What is the average lifespan of a cap in a speaker, before it should be replaced? Thanks, I appreciate and welcome all comments and opinions.

[SY]

Originally Posted by maindude

Hi Everyone,
I'm a newbie here, so please be gentle.

There, there, lad, we'll be nice!

I think there's no universal answer to "how long will a cap live." That's VERY dependent on who made it and how, what sort of environment it's in, and the level of abuse. If I were to replace the caps, I would absolutely use the same type of caps in the same position- differences in effective capacitance, ESR, and DA between different dielectrics can lead to significant frequency response changes which may not be what you want. And in general, electrolytics will deteriorate faster than film caps (though there are exceptions).

You could probably get away with using polyprpylene to sub for polyester, but even that's a bit dicey unless you're prepared to do some rigorous before-and-after measurements to see if you upset any applecarts. I have bad memories of some Magneplanar MG-1s I ruined by changing an electrolytic to polypropylene (at least that was reversible...).

[DigitalJunkie]

The electrolytic is probably about due,because of it's age. The film caps are probably fine,and could be left alone.

[maindude]

Originally Posted by SY

There, there, lad, we'll be nice!

I think there's no universal answer to "how long will a cap live." That's VERY dependent on who made it and how, what sort of environment it's in, and the level of abuse. If I were to replace the caps, I would absolutely use the same type of caps in the same position- differences in effective capacitance, ESR, and DA between different dielectrics can lead to significant frequency response changes which may not be what you want. And in general, electrolytics will deteriorate faster than film caps (though there are exceptions).

You could probably get away with using polyprpylene to sub for polyester, but even that's a bit dicey unless you're prepared to do some rigorous before-and-after measurements to see if you upset any applecarts. I have bad memories of some Magneplanar MG-1s I ruined by changing an electrolytic to polypropylene (at least that was reversible...).

Thank, very informative! I didn't realize the material made a difference as well. I had heard the rule of thumb was to replace ANY electrolytic cap with a metal poly cap of the same value. Thanks again, I recently changed out the the electrolytics in a pair of new Wharfedale EVO' 10's and thought I had lost something. This verifies that. I'll have to switch them back.

[maindude]

Originally Posted by DigitalJunkie

The electrolytic is probably about due,because of it's age. The film caps are probably fine,and could be left alone.

Thanks, I was hoping someone would say that. The old metallized poly caps are not a standard value and the new ones would have to be put in parallel to achieve the values needed. Those rascals can get expensive in a hurry!

[skeptic43]

This subject has been discussed and debated ad-nauseum over at AK.org.

[maindude]

Originally Posted by skeptic43

This subject has been discussed and debated ad-nauseum over at AK.org.

AK.org? Not famaliar.

[skeptic43]

Originally Posted by maindude

AK.org? Not famaliar.

I abbreviated. It's audiokarma.org. Check the speakers forum.

[maindude]

Originally Posted by skeptic43

I abbreviated. It's audiokarma.org. Check the speakers forum.

Will do. Thank you!