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XOVER Linkwitz-Riley
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• Page 1 of 1
XOVER Linkwitz-Riley
This is a typical application of the 4-channel FFT-based Audio Analyzer and IIR BiQuad filters. See the attached .fsm
ch1 : reference channel (no need to graph it)
ch2 : lowpass signal
ch3 : highpass signal
ch4 : reconstruction (lowpass + higpass)
reference : ch1
impulse response graph : ch4 (we can also graph ch2 or ch3 impulse response)
For implementing a crossover operating at 2 kHz, we need to configure the LR Xover :
2000 Hz
2nd-order (actually each speaker is going to be filtered 4th-order, as there are two Butterworth cells in series)
The resulting graph illustrates the LR Xover behaviour and properties.
The Lowpass slope in the transition band looks adequate.
The -6 dB point of the Lowpass is 2 kHz.
The Highpass slope looks adequate.
The -6 dB point of the Highpass is 2 kHz.
The Lowpass phase is a typical double Butterworth one, far from linear.
The Highpass phase looks essentially the same as the Lowpass. This guarantees that the speaker drivers operate in-phase from DC to 20 kHz. The multiway loudspeaker wont "beam" particular frequencies at particular angles. The radiation pattern stays homogeneous.
The Lowpass + Highpass sum delivers a signal exhibiting a distorted phase inherited from the twin Butterworth. The magnitude is flat from DC to 22 kHz. Such Xover produces a severe phase distortion. A pulse signal won't show as a pulse signal after the crossover. A pulse signal will appear as a burst extending over time. This is the green curve obtained from channel 4 setup as the Lowpass + Highpass sum. Such phase distortion is a serious disadvantage compared a Lipshitz-Vanderkooy Xover relying on a Bessel Lowpass inside.
The Lipshitz-Vanderkooy Xover is illustrated here http://www.dsprobotics.com/support/viewtopic.php?f=3&t=1505
Cheers,
Steph
ch1 : reference channel (no need to graph it)
ch2 : lowpass signal
ch3 : highpass signal
ch4 : reconstruction (lowpass + higpass)
reference : ch1
impulse response graph : ch4 (we can also graph ch2 or ch3 impulse response)
For implementing a crossover operating at 2 kHz, we need to configure the LR Xover :
2000 Hz
2nd-order (actually each speaker is going to be filtered 4th-order, as there are two Butterworth cells in series)
The resulting graph illustrates the LR Xover behaviour and properties.
The Lowpass slope in the transition band looks adequate.
The -6 dB point of the Lowpass is 2 kHz.
The Highpass slope looks adequate.
The -6 dB point of the Highpass is 2 kHz.
The Lowpass phase is a typical double Butterworth one, far from linear.
The Highpass phase looks essentially the same as the Lowpass. This guarantees that the speaker drivers operate in-phase from DC to 20 kHz. The multiway loudspeaker wont "beam" particular frequencies at particular angles. The radiation pattern stays homogeneous.
The Lowpass + Highpass sum delivers a signal exhibiting a distorted phase inherited from the twin Butterworth. The magnitude is flat from DC to 22 kHz. Such Xover produces a severe phase distortion. A pulse signal won't show as a pulse signal after the crossover. A pulse signal will appear as a burst extending over time. This is the green curve obtained from channel 4 setup as the Lowpass + Highpass sum. Such phase distortion is a serious disadvantage compared a Lipshitz-Vanderkooy Xover relying on a Bessel Lowpass inside.
The Lipshitz-Vanderkooy Xover is illustrated here http://www.dsprobotics.com/support/viewtopic.php?f=3&t=1505
Cheers,
Steph
- Attachments
-
- XOVER 2-way mono Linkwitz-Riley (2 kHz - Twin Butterworth 2nd Order).fsm
- (1.95 MiB) Downloaded 1199 times
-
- XOVER 2-way mono Linkwitz-Riley (2 kHz - Twin Butterworth 2nd Order) (600).png (78.23 KiB) Viewed 10731 times
Last edited by steph_tsf on Sat Aug 10, 2013 10:31 pm, edited 1 time in total.
- steph_tsf
- Posts: 249
- Joined: Sun Aug 15, 2010 10:26 pm
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