Replace KEF 104/2 caps - Electrolytic vs. Poly

I want to replace the 30 year old electrolytic caps in my 104/2's. The quote from Falcon Acoustics for replacement electrolytics is approximately $132 + shipping. They are currently out and may not have any in until end of 2015/beginning of 2016. The speakers currently sound pretty amazing, but I know those caps are way beyond their lifespan.

The electrolytics from Falcon are mostly +-2% tolerance which is pretty tight (this is what I believe stock tolerance was); however, it looks like there's a couple in the bunch that are of lower tolerance (see below).

7mfd 50v LL ( supplied as 7.5-6% = 7
3.3mfd 50v LL (supplied as LL 100V 2%)
4.2mfd 50v LL x2 ( supplied as 2+2.2 2%)
10mfd 100v(supplied as LL 100V 2%)
16mfd 100v
100mfd 50v x4
25mfd 100v
240mfd 70v ( supplied as 2x120 2%)
50mfd 100v
30mfd 100v
450mfd 50v ( supplied as 5%)
600mfd 50v ( supplied as 5%)

Now, if I were to replace with Solen Metalized Polypropylene (or similar), the tolerance would be +-5%. Additionally, this would cost quite a bit more. Note to mention, I'm not sure how easy it would be to find 240mfd, 450mfd and 600mfd caps (I'd probably have to run some smaller value caps in parallel). This would lead to increased cost, installation headaches, decreased enclosure volume, etc...

My question is, would there be any benefits/drawbacks to switching from electrolytics to polypropylene in this application? And no, I'm not going to even consider caps that are more expensive then Solens as I'm not made of money.

 

Personally, I find film/foil caps to be vastly superior to electrolytic, but they all have a flavor and it takes some playing around to find the sound you like. So, based on my experiences I would never use Solen for anything other than the shunt circuit and that's only if I couldn't use a better cap due to the value required.

In addition, you will find that all film/foil caps are much larger than electrolytics, so real estate is always a concern.

 

Looks like the pricing has gone up.
When I got a price last November it was closer to $100.
I think the examples of lower tolerance is because that's all that is now available

 

With that high of values of capacitance in a non-electrolytic capacitor - they would be huge and there wouldn't be any room left for the drivers or anything, never mind the expense.

With that said I would measure the existing capacitors (electrolytic) for ESR, or perhaps leakage at rated voltage. If they are approaching 20 years old - then it's a tough call if they test OK. 30 years? If they are in regular use they may be OK! It's long periods of disuse that tend to ruin an electrolytic. I would expect the high frequencies to be attenuated somewhat though, with old electrolytics. You will enjoy your speakers "all over again" like as not.

Make sure the replacements are of good quality. It is not my opinion that "audiophile" necessarily means good quality. Test the new ones for ESR and leakage before installation at any rate. I wouldn't be so concerned with their individual tolerance per se, but that they are closely matched. We want that for the best imaging and stereo separation, etc. You might get away with substituting poly for electrolytic on just a couple of the key capacitors if you want. Really Nichicon and other fresh stock capacitors would be just fine I bet.

I wouldn't shotgun them all at once - and remove the old components with care so they can be reinstalled if desired. Replace a few at a time and listen, see what you think sound wise.

 

This seems like a possibility:
http://www.erseaudio.com/Products/NonPolarElectrolyticAll

 

Hey, they actually have one of the hard to find caps I've been looking for. Unfortunately, out of stock.

 

Yeah, I was running into the same problem. I think I may end up doing electrolytics from 600uf up through 25uf then switch to something like Clarity Caps for 16uf through 3.3uf.

 

I come from the school of replacing all caps with the same type as the original schematic calls for.

 

Also, paper film/foil are too mellow for my liking. Ploys are the best, but with your values they would be large!

F1 nut. I just noticed you were currently residing at The Mars Hotel. Sweet!

 

I was thinking about this as well. Crossover design is certainly a black hole of research for me. Another question that I thought of is related to tolerance vs. quality. For example, would a better quality cap (made of higher grade material) with a lower tolerance (say 5%) sound better than a lower grade cap (cheaper, made of lesser material) with a tighter tolerance (say 1%). I'm assuming quality trumps tolerance up to a point.

 

It's a crap shoot I fear. I like to tell myselfotherwise, because I enjoy " upgrading" components, but in reality the difference may be null? Although, I strongly believe a systems approach to these things, and feel that every little detail/part matters.