recapping my beloved old speakers

Hi everyone,
I'd love to get advice on which caps to get to replace the ones in my RSC santa maria II. Not an expensive set of speakers but they sound amazing to me.
Since they are now approaching 40yo.. thinking recapping them would possibly get even better sound out of them..

from what I can see there are 3 caps per speaker
2x Callins CXPSD4-50NP 50V NP
1x Shizuki 6.8u FM50

What would you replace them with ?

Cheers!
 
Callins caps generally had their uF value stamped on them - see attached image.
 

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I ordered an ESR meter 🙂.. not a too expensive model.. on ebay : mers-100 v2.
Its not a fluke but should do the job!

As for caps, which brands should I look for ?
I intend to keep these for a longtime so going from 4$ caps to 40$ caps isn't going to kill me.... but would it change anything on these speakers ?

thanks everyone!!
 
Polyprophylene is reputed to be the least distorting, and smaller now than 40 years ago.
4 uf is not a standard value. I would parallel a 3.3 uf and a .68 uf cap.
digikey has a good stock of caps and ships to canada without involving the customs procedure. Look for passives, capacitors, film caps, then select for polypro dielectric, >50 v rating, values you need. I haven't noticed digikey selling any trash brands.
As far as your meter, would you drive on 40 year old tires? The rubber seals in your caps are that old. Dried up electrolytic caps sometimes only go 8% high on value, but go 2 or 4 times the original ESR value. The Peak meter comes with a chart of expected ESR values which I've found to be indicative except for low ESR caps built for modern switcher power supplies. The peak chart says a 4.7 uf 68 v cap has 19 ohms ESR, 4.7 uf 35 v cap 24 ohms.
 
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I'll leave it to others to wade into the topic of recommendations of particular models of caps (though I would agree with the advice about polypropylenes defining the base recommendation).

I too have beloved 40 year old speakers (Tangent RS4s) which might benefit from a re-cap. Myself, unless they failed demonstrably, I would be cautious about opening that can of worms... unless I was looking forward to a potentially lengthy project of cut and try.

If you're in the GTA you might consider buying from the Parts Connexion in Burlington. They seem to have many of the brands you might want to consider:


Film Capacitors



In addition there's Parts Express (though I've never ordered from them)


Metalized Polypropylene Crossover Capacitors - Parts Express
 
...going from 4$ caps to 40$ caps isn't going to kill me.... but would it change anything on these speakers ?
Changing to high voltage polypropylenes may result in your 40 year old speakers sounding a tad brighter and more detailed. Then again, you may prefer the sound you were getting with the old capacitors. I would first explore the effect that reasonably priced polypropylenes have on the sound before spending big money on exotic capacitors.
 
4μF polypropylene capacitors are available. Here's an example:

Dayton Audio DMPC-4.0 4.0uF 250V Polypropylene Capacitor
Parts express is in the US, Ohio. Sometimes they ship via UPS or Fed Ex. You don't get a choice of shipper at checkout, especially not USPS. Ask a Canadian about the $25 UPS/Fed Ex customs loan origination fee. Only Royal Mail handles customs charges COD. At least that is what Canadians have complained about on here.
Digikey crosses the border from MN in their own truck, handling customs to an office in CAN themselves. My favorite distributor, Newark, won't tell Canadians where they are shipping from people report. They will, however, ship USPS most of the time (not always).
 
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