From the12volt.com:
Crossover Definitions and Illustrations
Most crossover tutorials omit information about the simplest possible crossovers:
- A capacitor in series with the speaker (High Pass Filter)
- A coil (inductor) in series with the speaker (Low Pass Filter)
The first of these seems to be widely used as a quick and dirty way to protect small full range speakers from trying to do too much work on the low end. This is what I want to do, but I didn’t know how big of a cap to use. Many of the boxes I’ve made—little 3 watt per channel mini 4Ω speakers—drop out when turned up loud and during a big bass note. I’d like to limit this somewhat without removing more bass than I need to.
This site has what I need and some really nice, simple layout of its descriptions, complete with nice little diagrams.
So what size cap am I going to use? Even with a calculator, there isn’t an exact prescription. It looks like 200µF (-3dB at 200Hz with 4Ω) or even a bit smaller would be the usual recommendation, but I’m going to play with everything from there to 1000µF (-3dB at 40Hz). Another common cap size is 470µF (-3dB at 85Hz).
Next, I want to look into the possibility of using a line level filter instead of a filter placed between the amp and speaker. I’m not sure what Ω’s to use in the calculation and haven’t found anything useful online yet.
