Ok so I want this backwards. All passive crossover calculators I have come across till now provide you the capacitor and inductor values to be used for a given crossover frequency. What is the formula to derive the crossover frequency given the component value? I'm looking for formulas for 1st, 2nd and 3rd order Butterworth filters.
Secondly, I hope the formula accounts for both the capacitance and inductance (rather than being calculated using individual formulas), so that when XO frequency and let's say the capacitance value is given, we can derive the inductance.
Vinny
Secondly, I hope the formula accounts for both the capacitance and inductance (rather than being calculated using individual formulas), so that when XO frequency and let's say the capacitance value is given, we can derive the inductance.
Vinny
Vinnie try a little math.
if a=b*c then b=c/a. Get it?
Your home work:
if x = ((y+c)/2 + (z*b))/c
find the value of b.
Not that hard. Tedious but not hard.
if a=b*c then b=c/a. Get it?
Your home work:
if x = ((y+c)/2 + (z*b))/c
find the value of b.
Not that hard. Tedious but not hard.
Well, I know there's math involved and how a=b*c then b=c/a works. However, I cannot get to the math till I know the formula (equation) involved.
So, if you read my post, I asked for the formula, which unfortunately is not shown by any of the XO calculators out there that I came across.
single pole is easy.
Fr = 1/{2PiRC} or
Butterworth Filter Formula, Equations, & Calculations :: Radio-Electronics.Com
or
Butterworth Filter Design and Low Pass Butterworth Filters
or
https://en.wikipedia.org/wiki/Butterworth_filter
or
https://www.google.co.uk/url?sa=t&r...-0xwcy0Dg&sig2=8IJiIvs40ghlSHH-Gs7-Kg&cad=rja
etc.........
Fr = 1/{2PiRC} or
Butterworth Filter Formula, Equations, & Calculations :: Radio-Electronics.Com
or
Butterworth Filter Design and Low Pass Butterworth Filters
or
https://en.wikipedia.org/wiki/Butterworth_filter
or
https://www.google.co.uk/url?sa=t&r...-0xwcy0Dg&sig2=8IJiIvs40ghlSHH-Gs7-Kg&cad=rja
etc.........
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I don't know how this math of yours works 🙂.
If 6=2*3, then 2=3/6 or b=1/b
I'm very sorry for I don't have the formulae you are looking for.
I'll try to do something about it.
Lojzek, you got me there! I never validated the correctness of the equation by ppfred. I just copied pasted what he wrote. It was nothing but trolling. I never asked for coaching in elementary math. All I asked was for the correct formulas used for calculations in the Butterworth filter.
since you don't really know the filter alignment you can calculate the 2 corner frequencies. their spacing might give you idea.
best answer plug crossover values into a spice model and simulate with a load E.g. speakers Le and Re. now look where they cross over while adjusting for driver sensitivities.
Links on this page to different order xovers. sub-links show formulas as well as calculators.
Car Audio - Crossovers & Filter Calculator
Car Audio - Crossovers & Filter Calculator
With a second order filter, half the story is in the frequency of resonance between the capacitor and inductor. The rest is in the damping, or load, and the acoustic response of the speaker. No straight answers here.
LC - fresonance:
1/(sqr(LC)*6.3)
LC - fresonance:
1/(sqr(LC)*6.3)
BW1:
Rtw=1/(2*pi*Fc*C)
Rw=2*pi*Fc*L
BW2:
Rtw=1/(2*sgrt(2)*pi*Fc*C1)
Rw=1/(2*sqrt(2)*pi*Fc*C2)
Rtw=sqrt(2)*pi*Fc*L1
Rw=sqrt(2)*pi*Fc*L2
BW3:
Rtw=1/(3*pi*Fc*C1)
Rtw=1/(pi*Fc*C2)
Rw=2/(3*pi*Fc*C3)
Rtw=(8*pi*Fc*L1)/3
Rw=(4*pi*Fc*L2)/3
Rw=4*pi*Fc*L3
Rtw= tweeter's rated impedance (ohms)
Rw= woofer's rated impedance (ohms)
Fc=crossover frequency(Hz)
L= inductance (H)
C= capacitance (F)
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