Hello, I recently started building a portable woofer with 4" JBL driver and everything seems fine, I learned how to wire a line out to amplifier using divider resistors.
Now the question: I found a 4th order 2way crossover schematics on this page: Linkwitz-Riley Electronic Crossover
I'm satisfied with the low pass part of 2-way crossover, but I would like to make the high pass (subsonic) filter 8th order instead of 4th. Is it that simple as just stacking two identical 4th order filters, or will something such as Q value change by doing this?
Secondly, I'll use single supply LM258 op-amps, should there be bypass capacitors from Vcc to GND and is 0.1uf film cap sufficient if it'll be powered from batteries? Thank you! Build log will be created in upcoming weeks.
Now the question: I found a 4th order 2way crossover schematics on this page: Linkwitz-Riley Electronic Crossover
I'm satisfied with the low pass part of 2-way crossover, but I would like to make the high pass (subsonic) filter 8th order instead of 4th. Is it that simple as just stacking two identical 4th order filters, or will something such as Q value change by doing this?
Secondly, I'll use single supply LM258 op-amps, should there be bypass capacitors from Vcc to GND and is 0.1uf film cap sufficient if it'll be powered from batteries? Thank you! Build log will be created in upcoming weeks.
Why would you change the subsonic filter to 8th order? Generally 4th order is fine, 2nd order also is sufficient. A 2nd order filter can be given a high (0,7 - 2,0) Q in order to boost bass near the lower cutoff.
Subsonic filters usually are of the Butterworth type because they are maximally flat within the pass band. Higher orders can be made by cascading second order stages (a second order stage has a Q and a frequency), each with a certain Q factor which can be looked up in a table: Cascading filters | EarLevel Engineering For 8th order Butterworth you need Q = 0.50979558; 0.60134489; 0.89997622; 2.5629154.
Opamps indeed should be bypassed, with 100 nF ceramic capacitors (preferably one for each opamp, as close as possible to the opamp) and some larger electrolytic capacitors (one of say 100 µF on each circuit board is sufficient).
Subsonic filters usually are of the Butterworth type because they are maximally flat within the pass band. Higher orders can be made by cascading second order stages (a second order stage has a Q and a frequency), each with a certain Q factor which can be looked up in a table: Cascading filters | EarLevel Engineering For 8th order Butterworth you need Q = 0.50979558; 0.60134489; 0.89997622; 2.5629154.
Opamps indeed should be bypassed, with 100 nF ceramic capacitors (preferably one for each opamp, as close as possible to the opamp) and some larger electrolytic capacitors (one of say 100 µF on each circuit board is sufficient).
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Thanks. When modeling in WinIsd I just saw that Linkwitz-Riley cuts a lot of low frequencies (because of it's -6db point nature) so this variant is not suited for subsonic filter. What do you think of this Butterworth calculator's values, can it give the standard 0.707 Q? Screenshot 20180520 181547 — imgbb.com
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