My high efficiency speaker system has evolved into a two-way setup using a 15" Gauss 4580A on the bottom, augmented by a JBL 2446J on the top end. Crossover frequency is 500Hz.

The JBL crossover consists of (in order, from input jacks to speaker terminals):

- 12 dB rolloff using the appropriate cap and coil
- a Parts Express 260-261 16 ohm L-pad (see link below)
- impedance compensation
- CD equalization

My question centers around the L-pad I'm using....

Now that I've got the levels matched between the Gauss and the JBL, I plan on removing the cheesy rotary pot and replacing it with Mills resistors of the appropriate value. Without disturbing it, I removed the pot last night to measure the equivalent values of R1 (series resistor) and R2 (parallel resistor), and came up with the following:

R1 = 6.0 ohm
R2 = 5.5 ohm

Just for kicks, I decided to verify these values with the formulas found in Vance Dickasons Loudspeaker Cookbook. It turns out that they were way different! According to his formulas, a R2 of 5.5 ohm should calculates to a R1 of 12 ohms!

Should I just ignore the theoretical values and replace the pot with the values I measured? If not, can anyone help me with the proper calculations for this L-pad?

Thanks in advance,

Mike

• Parts Express 16 ohm L-pad....