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I recently ordered 2 Alcap 8 Mfd 50 V electrolytic caps to replace the ten year old ones in each of my speakers crossover. They are the exact same brand and both say 8 Mfd 50 V on them. However the new ones are smaller (about maybe two thirds the size of the old ones). At first I thought they sent me the wrong ones, but double checked the one in my my crossover and was surprised to find it is indeed the same value and voltage specs as the new ones I got. I guess that's all that matters but wanted to see if anyone here has experienced "downsizing" with electrolytics. Thanks for any input.
Follow Ups:
For a small size like 8uf you might want to try a film cap instead of a lytic.
Many caps employ flash cap technology. The capacitance is determined by the surface area of the parallel surfaces. Manufacturers can increase the area by acid etching the surface, thus roughening it, and thus giving higher capacitances in a smaller package.
I am not convinced it is 'better' in performance than the older smooth film caps, however.
New techologies have even made electrolytics smaller.Of course this also means it is not the same capicitor is was ten years ago.
I compared them last night and the new ones are actually closer to half the size, measuring about 15 mm long and 7mm wide as compared to 30mm long and 10mm wide. When you say the newer electrolytics are not the same does this mean I can't use it eventhough it is still rated at 50 volts and 8Uf, just like the old one? The electrolytic is followed by a small Mylar cap rated 1.5K 100 Volts. The ripple current on the new smaller Electrolytic Alcap is 450 ma, I don't know what the ripple current rating on the older one was. The speaker is a small UK monitor with a 5 inch woofer and rated 8 Ohms with the curve never dropping below 6 ohms. My amp is 25 watts and puts out about 3 amps of current, I also use a 60 watt amp that puts out about 7 amps of current. The speakers are'nt current hungry and are rated to handle 100 watts. My idea of getting the same brand and value replacement was because I wanted to keep things closer to the same as possible and also there is not room to fit a larger Poly Cap into the network panel. Will I screw things up by installing the new smaller Alcap elctrolytic regardless if it's the same value? Thanks for the responses.
Just make sure they are bi-polar caps. If they have a positive and/or negative terminal marked on them you bought the wrong type. Otherwise you are fine. Ripple current isn't a factor for speaker caps, only the voltage rating.Of course you could buy a much better quality cap but that is up to you.
Yes they are non polar 10% tolerance, same exact specs, just smaller. The alcap is known to be one of the better audio grade electrolytics and commonly used in some of the best British speakers. If not for the space factor I might consider using larger polyprops, though I read here that some feel it's best to stick with original parts in a crossover network, that switching may result in tonal changes that would be different but not neccesarily better, so that and the space factor weighed in my decision. Thanks for your help. I'm going to replace one of the internal wires which was oxidizing while I'm at it. All I have to do now is brush up on my soldering.
Some people say good electrolytes in crossovers sometimes work better than polypropilene
They are. However, many of them will not handle the current required in a speaker applications and will degrade quickly and/or fail. Look for caps with a high ripple current rating,several amps, and of course, non polarized.
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