I replaced the new polypropylene capacitors with electrolytics that mimicked the old ones & the speakers sound amazing!
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?
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@jmncbh Glad you are happy. For future reference here is information to consider. The 100 uF cap was likely in the woofer circuit. Finding a reasonably sized 100 uF Poly cap is a challenge. You probably discovered that. Can usually get away with good quality electrolytic cap in the woofer circuit. Although, it was proven years ago that electrolytics should never be used in a crossover circuit at all. Manufacturers continue to use them due to small size and very cheap price. Poly caps are the best choice for midrange and tweeter circuits, hands down. Air core inductors are far superior also. Again, due to size and cost considerations, iron core inductors are frequently used. Sand cast resistors are bad, but still frequently used due to cost. Do you sense a theme. Manufacturers skimp on crossover parts because they know most buyers will never compare with better quality parts. Lastly, ignore advice from Chatgpt. |
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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