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Saving old vintage gear is a lot harder than people make it out to be.

I’ve been trying to save my Eosone rsf-600 speakers for a few months now. I noticed the highs were muffled & discovered that two electrolytic capacitors (16uf & 100uf) are used as some sort of shunt in the crossover design. I saw a Paul Mcgowan video (one of the dudes who designed the Eosones) where he makes a reasonable claim that electrolytics should be replaced by polypropylene due to the aging factor. That fixed a few problems; although, something seems off about the sound. Replacing old electrolytic capacitors is not as simple as putting in new polypropylene capacitors; there must have been some fine tuning with the orignal electrolytics in mind. The brand is made by tecate industries. Both are 50v 10± tolerance and they are both relatively small radial leads. There’s no point in buying an expensive tool to measure esr since the orignal caps must have changed in value. Are my Eosones screwed? Chat gpt has said to add resistors to poly caps but isn’t esr different for higher frequencies in electrolytics?

jmncbh

Showing 1 response by viridian

viridian's avatar
viridian
5,215 posts
 

The ESR of an electrolytic cap is almost always higher than a poly cap of the same value. We tend to think of capacitors as having a capacitive value, but forget that they have a resistive value as well.

Replacing the original electrolytic caps with current production electrolytic caps will more closely approximate the original ESR and get the filter parameters closer to the original design. 

It is often best to try to replace a crossover cap with one that matches in capacitive value and ESR, and meets, or exceeds, the original voltage spec.

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