as above.
I was looking at crossover and notice the wirewounds 15W that's being used.
I'm wondering if
I was looking at crossover and notice the wirewounds 15W that's being used.
I'm wondering if
- the current going through the resistor is constant (thus the resistor temp is constant)
- OR perhaps the resistor only warms up in certain situations (playing loud music or maybe the resistor only warms up if certain frequencies are played)
Since music or typical recorded sound is AC with varying frequency and amplitude, the resistor warming is dependent on these and for what function it is placed in the crossover.
Speakers are essentially responsive to voltage. Resistors are not at all dependent on frequency for audio.
To size resistor power, calculate (or measure) the largest RMS AC voltage (V) it will ever be exposed to. Then use this to get the power:
Power(watts)= V²/R
Finally, to increase reliability and prevent thermal Ohm value drift, double or triple that wattage number. That is the wattage value you should shop for. If you end up needing to use a wirewound resistor, make sure it is the non-inductive type.
To size resistor power, calculate (or measure) the largest RMS AC voltage (V) it will ever be exposed to. Then use this to get the power:
Power(watts)= V²/R
Finally, to increase reliability and prevent thermal Ohm value drift, double or triple that wattage number. That is the wattage value you should shop for. If you end up needing to use a wirewound resistor, make sure it is the non-inductive type.