Crossover Cap Question

[jjohnson]

I'm rebuilding a set of Magnepan MG2Bs. I've rebuilt several pairs and have replaced the caps in a couple of them. Each of these speakers has 4(ea) 5uf caps. At Parts Express I can purchase 5.1uf caps at much higher tolerances for not much money. However, I'm wondering why I should buy a single 20uf cap to replace the four 5uf caps. I could buy a couple of very high end caps to replace the 8 lower quality caps that came originally.

Please tell me what I'm missing here and please type slowly as my electronics knowledge is very limited.

Thanks in advance.

 

[67dylan]

Are they wired in a bundle? IF so, no reason not to purchase a single 20uF. You don't need to by the high end stuff; tighter tolerances sometimes shows weakness in other components. The Dayton Audio components are good. I've bought many a' parts from Parts Express and built a few of their DIY builds. I need more $$ and more time to build more speakers.

http://www.parts-express.com/dayton-audio-dmpc-20-20uf-250v-polypropylene-capacitor--027-436

 

[jjohnson]

Thanks for the info. Given my level of ignorance, I am posting photos for confirmation.

 

[R Swerdlow]

67dylan is right. A single 20 µF cap is equal to four 5 µF caps wired in parallel with each other. They cost $7.11 each vs. $11.16 for four of the 5.1 µF caps. I assume you have two speakers to do.

The Dayton polypropylene caps are very good. Despite all the claims on the internet, there is no audible benefit from using the so-called high end caps instead of the Daytons.

Edit: I just saw your photos. Those four caps are wired in parallel.

 

[Andyman]

Is there a room issue? Is the diameter of a single Dayton poly too big? They're 28.5mm, or about 1 1/8", so lots thicker than those flatter stock caps.

 

[dc270]

One thing to consider if you have not already is the tolerance. You stack several 5% tolerance caps together, well your single cap tolerance of just 5% just shot up to 20%!!
I like Dayton caps just fine, the 1% and the 5% types. I do want to keep my tolerances in check though......
DC

 

[jjohnson]

The original caps were 10% tolerance. I'm sure that any decent cap will do better than that. If I can replace the original 4 caps at 5%, I'm sure that I'd be better off. At 1%, it would be much better. I just want to make sure that a single cap can replace the original 4 without messing anything up.

 

[Steve O]

One thing to consider if you have not already is the tolerance. You stack several 5% tolerance caps together, well your single cap tolerance of just 5% just shot up to 20%!!
I like Dayton caps just fine, the 1% and the 5% types. I do want to keep my tolerances in check though......
DC

Actually, tolerance stack-up doesn't work that way if you're working with a percentage. In this specific case, at worst you'll end up with a composite 20uF cap within the same percentage tolerance as the component 5uF caps. In most cases the value of the composite cap will actually be closer to the theoretical composite value percentage-wise than any of the individual component caps due to effects of averaging. The latter is esp so if component cap value variation is the result of a "normal" production variation about the nominal value.

 

[67dylan]

I had no idea what kind of speakers you have, luckily Google is my friend. Man, those are some nice looking speakers, I bet they sound magnificent. Anyway, from what I can see there should be no problem with the cap size; am I correct? I saw someone had a pic of their crossover update and they had a large cap as well. Good luck and hope those speakers come out great for you. Can you post a pic when they are done, love to see them.