Merged your thread with an older one with the same topic. See the OP. First order filters have pretty limited application.
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Help designing line level high pass filter?
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Merged your thread with an older one with the same topic. See the OP. First order filters have pretty limited application.
Jim Taylor
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Actually, passive line level crossovers (PLLO) of any order don't get a very high rating from my favorite Australian curmudgeon, Rod Elliot. However, he has a page about them for people who are, as he says, "obsessed" with them ... and it includes second-order slopes, too.
I did a quick search and found this calculator at the bottom of the page
"This calculator is for an active noninverting op amp high pass filter.
This op amp high pass filter produces a noninverting signal at the output. This means that the output signal is exactly in phase with the input signal.
Resistor R and capacitor C set the cutoff frequency point.
Frequencies above this cutoff frequency get passed to output. Frequencies below this cutoff frequency point are greatly attenuated.
The formula for calculating the cutoff frequency is, frequency= 1/2πRC
The resistor R2 and resistor R1 determine the gain of the circuit. The gain of the circuit is determined by the formula, gain (AV)= 1+ R2/R1.
For this calculator, a user just has to enter the cutoff frequency and the gain desired. The calculator will then compute the resistor R, capacitor C, resistor R2, and resistor R1.
Just as with the other op amp filter circuit, the specifications of this op amp must be considered."
Regards
High Pass Filter Calculator
This is a High Pass Filter. It calculates the range of high frequency signals that a filter passes through.
www.learningaboutelectronics.com
"This calculator is for an active noninverting op amp high pass filter.
This op amp high pass filter produces a noninverting signal at the output. This means that the output signal is exactly in phase with the input signal.
Resistor R and capacitor C set the cutoff frequency point.
Frequencies above this cutoff frequency get passed to output. Frequencies below this cutoff frequency point are greatly attenuated.
The formula for calculating the cutoff frequency is, frequency= 1/2πRC
The resistor R2 and resistor R1 determine the gain of the circuit. The gain of the circuit is determined by the formula, gain (AV)= 1+ R2/R1.
For this calculator, a user just has to enter the cutoff frequency and the gain desired. The calculator will then compute the resistor R, capacitor C, resistor R2, and resistor R1.
Just as with the other op amp filter circuit, the specifications of this op amp must be considered."
Regards
I got a Xkitz balanced cross-over for a 2way at 170Hz with an 4th order slope and it worked fine with the correct 24dB slopes. As my low mid/high drivers have naturally a 18dB slope at 150Hz I tried also them without cross over and it sounded much better as the Xkitz introduced easily noticeable distortions. But in order to protect the mid-high driver I thought to use a 1st order PLLOX. That sounded much better than the active version and still gave me the desired slope of 24dB/octace (combination of natural low roll off and 1st order slope).
I used PLLOX crossovers years ago but I thought there is no real reason for the resistor in the RC network(except to regulate sound pressure). So I calculated the capacitor value with the standard 1st. order formula for speakers except I used the input impedance of my amplifier (Starkrimson 25 amp module with 44kΩ) yielding 20nF. So using active only for lowpass and a pair of matched capacitors for high pass sounds great
I used PLLOX crossovers years ago but I thought there is no real reason for the resistor in the RC network(except to regulate sound pressure). So I calculated the capacitor value with the standard 1st. order formula for speakers except I used the input impedance of my amplifier (Starkrimson 25 amp module with 44kΩ) yielding 20nF. So using active only for lowpass and a pair of matched capacitors for high pass sounds great
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