Need specific replacement capacitor info for N-800 8K Networks

[Tortie]

I have inherited a set of really nice 846B valencia's from the in laws. They gifted them to me before I would inherit them haha. Cabinets in great shape, and even the front screens are present and in good shape.

The high frequency horn on one was not working so I did my web research and found Great Plains Audio and dutifully sent both of the grapefruit sized business ends of the horns to Bill for new diaphragms and remagnetizing.

Now it comes to crossovers. I learned that the crossover capacitors are likely feeling their age and need replacing. A little background,...I am a licensed aircraft mechanic, well versed in mechanical doings,...so I am fully capable of identifying and resoldering in two capacitors. Problem is,...when I do a search for the capacitors I get a zillion,...and I do mean a zillion, hits for capacitors with those values. Bill at GPA said to be sure to get capacitors with the same general size as the old ones in order to carry the intended power. Makes sense, as you can get capacitors with the right electrical value that are tiny, and that would not be good. So,....I wanted to find something that would work for my situation.
When I do forum searches I get threads like "I recapped the crossovers", and "just replace the capacitors", and "got some capacitors online and put them in."

All this is well and good,...but what I am hunting is specific stock numbers, and a specific company, and a specific web site where I can get the two specific capacitors I need to get.

I am not wanting to get into building new crossovers, improving the crossovers, or showing my audio expertise,...I have none. Just wanting to do what's right to get these great old speakers safely playing again for another 40 years. Hopefully someone has specific info I need, and where to get them. Or maybe someone here sells exactly what I need?

Specs are:
N800-8K Network
8 ohms
846-B

Large capacitor reads:
NP
CALLINS 7239
9-CXPSD21-75NPS
21uF-75V NP


Small capacitor reads:
NP
CALLINS 72??
8-CXPSD8-75NPS
8uF-75V NP

Thanks guys.

[Tortie]

Ok,...further web searching has revealed a possible solution to my inquiry. I found these after seeing this company name pop up in several old forum posts.
These are what I am considering buying to replace my caps in my crossovers.

http://www.parts-express.com/dayton-audio-pmpc-20-20uf-250v-precision-audio-capacitor--027-252

and

http://www.parts-express.com/dayton-audio-pmpc-82-82uf-250v-precision-audio-capacitor--027-242

These look the part dimensionally, but the capacitance isn't an exact match. I know these things all have a tolerance,...but am I going to be ok with using a 20 uF in place of a 21 uF,..and an 8.2 uF in place of the 8uF. ?? Probably ok from what I've read, but want to ask some experts to be sure because I am not an electronics guy.

[Ruediger]

<snip>
These look the part dimensionally, but the capacitance isn't an exact match. I know these things all have a tolerance,...but am I going to be ok with using a 20 uF in place of a 21 uF,..and an 8.2 uF in place of the 8uF. ?? <snip>

You can connect capacitors in parallel, so 21 uF = 20 uF || 1 uF. If you can't find a proper 20 uF with the right tolerance then you can build that from several smaller ones.

100 V is right, you don't need more.

Ruediger

[Tortie]

Thank you Ruediger for the tip on the capacitors that can be wired in parallel. That solves my problem of not being able to find the exact value. That's practical advice that a guy can really use,...a perfect justification for the value of forums. Thanks.

One last small question, at the risk of further showing my ignorance of most things electronic,...you mention that 250volts is overkill,...but beyond that just being the case, is there any detriment to overkill on the voltage carrying capacity? My feeling is that it's not a problem, but it doesn't cost me anything to ask eh?

Ok, so my plan is to buy these Dayton capacitors from Parts Direct, and add some smaller capacitors of the same manufacturer to dial in the exact factory Altec values of the originals. Any problems or suggestions with this approach?

If not, I'll get them on the way to me so I can get the crossovers done for when the speaker parts come back from GPA.

[Ruediger]

250 V is just overkill, it costs more and takes up more space. Apart from that it is okay.

Ruediger

[Tortie]

Ok, so now today I got two good deliveries. The high frequency horn parts got here from GPA, all rebuilt and ready to go. And the package from Parts Express with my capactors arrived also.

Now,...to further show my electronics ignorance,...I know enough that capacitors should observe polarity,,....but on these Dayton capacitors I see absolutely zero markings that would indicate polarity. (!) And,..the real ignorance,...I would need some advice on which "end" of the wire on the actual crossover circuit board I'm faced with is positive and negative.

The old capacitors "Collins" brand had no markings about polarity either.
What gives? Am I missing something, or are these type capacitors not polarity sensitive?

[grumpy]

The NP meant non-polarized, as are your new parts.

[Tortie]

Well,...you may be grumpy,...but you are awfully helpful, haha.
Thanks.

That's just what I needed to know.

Soldered in the caps, and assembled the horns.
Wow,...Steely Dan's "Peg" never sounded so good.

Thanks guys.

[grumpy]

:thmbsup: