# DIY Audio & Video

## 2-Way Crossover Design / Calculator Help

Use the 2-way Crossover Designer.

Crossovers are used to filter certain frequencies from a driver. A High Pass Filter (HPF) filters out low frequencies - for example, removing bass from a tweeter. A Low Pass Filter (LPF) filters out high frequencies - for example, removing treble from a woofer. Crossovers are necessary to prevent overlap in frequency response from different drivers in a system, and to prevent a driver from producing frequencies it was not designed for. See the Crossover Tutorial & Crossover FAQ for more information.

Typically, lower order crossovers are preferred when possible. The more gradual reduction in the speaker response is less noticeable than the sharp reduction from a higher order crossover, making it more difficult to notice the crossover point. Low order crossovers are also cheaper and easier to make. The issue with low order crossovers is that the reduction in driver response might be so slow that the driver cannot handle some frequencies at the required load.

Note that some crossovers can produce phase shift problems. A second order crossover will shift the phase of each speaker 90 degrees, so that both speakers are 180 degrees out of phase. This means that at the crossover frequency, the two drivers will be moving in opposite directions at the same time. They will cancel each other out and produce a 30db dip in the frequency response at the crossover point. Reversing polarity of one (but not both) of the speakers will limit this dip to +- 3db.

Here are the formulas for 1st, 2nd, 3rd, 4th, & 6th order crossovers. Use the tables below each diagram to look up the cratio and lratio values. The results are multiplied by 1,000,000 to convert Farads (F) into microFarads (uF) and by 1,000 to convert Henries (H) into milliHenries (mH) values.

#### 1st Order Crossovers

Rh = Driver Impedance of the High Freq Driver in Ohms

Rl = Driver Impedance of the Low Freq Driver in Ohms

f = Crossover Frequency in Hz

ButterworthSolen Split
cratio1.1590.1125
lratio1.1592.2251

#### 2nd Order Crossovers

cratio1.0796.1125.0912.1592
cratio2.0796.1125.0912.1592
lratio1.3183.2251.2756.1592
lratio2.3183.2251.2756.1592

#### 3rd Order Crossovers

ButterworthBessel
cratio1.1061.0791
cratio2.3183.3953
cratio3.2122.1897
lratio1.1194.1317
lratio2.2387.3294
lratio3.0796.0659

#### 4th Order Crossovers

cratio1.0844.0702.1040
cratio2.1688.0719.1470
cratio3.2533.2336.2509
cratio4.0563.0504.0609
lratio1.1000.0862.1009
lratio2.4501.4983.4159
lratio3.3000.3583.2437
lratio4.1500.1463.1723
LegendreGaussianLinear Phase
cratio1.1104.0767.0741
cratio2.1246.1491.1524
cratio3.2365.2235.2255
cratio4.0910.0768.0632
lratio1.1073.1116.1079
lratio2.2783.3251.3853
lratio3.2294.3253.3285
lratio4.2034.1674.1578