I'm wrapping up my first 3-way crossover design and am looking at the impedance curve of the system.
How low is too low impedance?
And what is the significance of phase angle?
Any other issues I should be concerned with on this chart?
How low is too low impedance?
And what is the significance of phase angle?
Any other issues I should be concerned with on this chart?
It’s largely determined by parameters of the power amplifier stage, including its power output capability and cooling capacity. Too low of an impedance causes the speaker to pass a lot of current, and this causes heat dissipation in the amplifier, voice coil and crossover. If the impedance magnitude drops in part of the bandwidth it may clip sooner than other frequencies, when dynamics are played back near the amplifier’s limit.
The relevance of the phase angle can be looked at in relation to the amplifier’s phase margin. Too great of a phase swing at too low of an impedance can cause an amplifier to become unstable.
I designed crossovers with power factor correction to flatten the phase and even out the impedance. While my amplifier is rated for 1 Ohms, my goal was to have safe and sane crossovers that any amplifier could drive.
The impedance shown in your graph is very low above 4kHz and the phase swing is 60deg around 3.7kHz. Now, the power distribution of music is often lower in that frequency range, and I don’t know your design goals, but in a day and age of compressed music I would have kept it upwards of 4 Ohms with a target of 6 Ohms. The peak in the midrange could also be flattened.
The relevance of the phase angle can be looked at in relation to the amplifier’s phase margin. Too great of a phase swing at too low of an impedance can cause an amplifier to become unstable.
I designed crossovers with power factor correction to flatten the phase and even out the impedance. While my amplifier is rated for 1 Ohms, my goal was to have safe and sane crossovers that any amplifier could drive.
The impedance shown in your graph is very low above 4kHz and the phase swing is 60deg around 3.7kHz. Now, the power distribution of music is often lower in that frequency range, and I don’t know your design goals, but in a day and age of compressed music I would have kept it upwards of 4 Ohms with a target of 6 Ohms. The peak in the midrange could also be flattened.
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