Phase shift on a first-order crossover is 90 degrees.
Second Order (12db/octave) Two-Way
Crossover
Linkwitz-Riley crossovers match attenuation slopes so that
system response is flat at crossover point.
Butterworth crossovers yield to a peak at the crossover
frequency.
Bessel crossovers have a frequency response between
Linkwitz-Riley and Butterworth crossovers.
The phase shift on a second-order crossover is 180 degrees
(reversed polarity).
Third Order (18db/octave) Two-Way
Crossover
Phase shift on a third-order crossover is 270 degrees (-90
degrees).
Fourth order (24dB/octave) Two-Way
Crossover
The phase shift on a fourth-order crossover is 360 degrees =
0 degrees (no phase shift).
Zobel Circuit (Impedance
Stabilization)
Even though speakers are rated at a certain
"resistance" (i.e. 4 Ohms), the actual impedance varies with frequency (speakers
have inductance). To compensate for the non-linearity of speakers (on mainly subwoofers),
Zobel circuits are used.
Re is the DC resistance of the woofer (can be measured with
an ohmmeter)
Le (or Lces) is the electrical inductive equivalent of the
driver.
L-pad (Speaker Attenuation)
An L-pad circuit will attenuate a speaker.
L-pads keep the load "seen" by the amplifier
constant, affecting only the power delivered to the speaker. The power delivered by
the amplifier remains constant.
Since L-pads are made from resistors, it does not induce any
phase shifts, or affect frequency response.
* Original calculator design by Speakermania (link
will open in new window).
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