Originally Posted by
Baron030
The resistors form a fixed L-Pad attenuator, which sets an upper limit to the amount of power that is sent to the high frequency driver. And this also reduces the heat load on the variable 8 ohm L-Pad network. A 4 ohm series resistor combined with a 7.5 ohm shunt resistor will drop to signal by 6.2 db. While a 5.1 ohm series resistor combined with a 7.5 ohm shunt resistor will drop to signal by 7.3 db. The difference of 1.1 db can be easily be balanced out by the variable L-Pad network. But, the impedance load on the C1 and L1 high pass network is different, meaning that the crossover point would be shifted slightly between the two networks. And I am not sure that this would be noticeable as the impedance would be 7.87 ohms with the 4 ohms series resistor and 8.97 ohms with the 5.1 ohm series resistor. Still, if these were my crossover networks, I would want them to match. So, I would suggest replacing the 4 ohm R1 resistor with a 5.1 ohm resistor.
Baron030:)