Hello to all. I was wondering if increasing or decreasing the value of a cap would help to increase bass definition on my 32 year old Allison 8 speakers. It currently has two 60uF electrolytic caps in parallel for 120 uF. My plan is to replace it with one 120uF metal film polypropylene cap. All the other caps have been replaced with the polypros. Those values are 12, 24 and 5.2uf
Any input would be appreciated
Thanks
Any input would be appreciated
Thanks
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Check the as-designed ESR of those two electrolytics; it may be a part of the transfer functions. If so and you replace with an MKP, you may need to add some series R with the new caps to compensate.
The electrolytic caps may have lost some of their nominal value too, a simple and cheap fix would be a new electrolytic one. Those probably are on the parallel section of the woofer, metal film caps don't bring you much of a gain here. But if you opt for the MKP, add a series resistor of about 1,5Ω. Or correct for the ESR of a new electrolytic cap, since the old ones aren't to be trusted anyway.
Short answer is no. I highly doubt that bass definition is influenced by the crossover, not only the caps alone. With 32 years old speakers you likely have deterioration problems in the drivers (ageing surround and spider, or even the magnet), so it is likely that the bass now is not what was supposed to be.
As for the caps, the only real problem with electrolytic ones is that they change value when old, so you should replace them. My suggestion, as always is to replace electrolytic with electrolytic, and not film caps. This is because electrolytic caps have a much higher ESR than film caps, and using a film cap where there was an electrolytic makes the crossover not working anymore as intended.
I would also revert to electrolytic the new MKP, you likely changed the brightness of the tweeter and mid using MKPs instead of electrolytic caps.
Ralf