General xo question

[randy]

With a given xo for a tweeter and single woofer, would the xo change if you were to add an additional woofer as in a mtm.

[Zero the Hero]

absolutely - you're changing the impedence of the woofer circuit

[mzisserson]

absolutely - you're changing the impedance of the woofer circuit

Yes, Furthermore since you are differing the woofer's impedance and increasing the output with another, you will need to tweak the tweeter circuit as well.

[Chris Roemer]

Yes, Furthermore since you are differing the woofer's impedance and increasing the output with another, you will need to tweak the tweeter circuit as well.

Additionally, you can get CLOSE to what's needed:

If you're halving the woofer's impedance (two 8 ohmers in parallel), cut the coil value in half, and double the values of any caps. If you've got a Zobel, double THAT cap, and halve that resistor too. You gain approx. +6dB in woofer output, so decrease any tweeter attenuation by about 6dB as well.

If you're doubling the woofer's impedance (two 4 ohmers in series), then just double up any coil or resistor values, and halve any caps. This arrangement does NOT net you any extra woofer sensitivity, so the high pass on the tweeter should be OK.

Chris