Hi folks . . .

I'm trying to design a crossover for an MTM system using a pair of SEAS ER18RNX wooofers and a 27TDFNC/GW tweeter. Zaph Audio has a 2-way system, the SR71, using the same woofer, but a different SEAS tweeter. Specs for his drivers are:

Tweeter: 6 ohm (nominal) Re = 4.8 ohm

Woofer: 8 ohm (nominal) Re = 5.9 ohm

Crossover 1750Hz.

Actual component values Zaph uses:

Hi-pass filter: C1 = 12uF

L1 = 0.15mH

Lo-pass filter: C2 = 12uF

L2 = 3.3mH

Both filters are LR2.

But two different calculators give these values:

--- if you use nominal impedance:

C1 = 7.58 uF

L1 = 1.09mH

C2 = 5.69uF

L2 = 1.46mH

--- if you use Re:

C1 = 9.48

L1 = 0.87mH

C2 = 7.71uF

L2 = 1.07mH

2-Way Crossover Designer / Calculator

mh-audio.nl - Crossover Networks

The audio.nl calculator indicates you should use Re. The DIY merely asks for "speaker impedance," which one would assume to be the nominal impedance.

Which should one use?

In either case the values are wildly different from those Zaph is using. He does have a notch filter on the tweeter. Does that resistance need to be included in the tweeter Re? Does it affect the values of the woofer cap and coil also?

I've done these comparisons with a couple other actual v. calculated crossovers. None of them agree.

Are these calculators of any value? Am I misusing them?

Thanks for any help!

I'm trying to design a crossover for an MTM system using a pair of SEAS ER18RNX wooofers and a 27TDFNC/GW tweeter. Zaph Audio has a 2-way system, the SR71, using the same woofer, but a different SEAS tweeter. Specs for his drivers are:

Tweeter: 6 ohm (nominal) Re = 4.8 ohm

Woofer: 8 ohm (nominal) Re = 5.9 ohm

Crossover 1750Hz.

Actual component values Zaph uses:

Hi-pass filter: C1 = 12uF

L1 = 0.15mH

Lo-pass filter: C2 = 12uF

L2 = 3.3mH

Both filters are LR2.

But two different calculators give these values:

--- if you use nominal impedance:

C1 = 7.58 uF

L1 = 1.09mH

C2 = 5.69uF

L2 = 1.46mH

--- if you use Re:

C1 = 9.48

L1 = 0.87mH

C2 = 7.71uF

L2 = 1.07mH

2-Way Crossover Designer / Calculator

mh-audio.nl - Crossover Networks

The audio.nl calculator indicates you should use Re. The DIY merely asks for "speaker impedance," which one would assume to be the nominal impedance.

Which should one use?

In either case the values are wildly different from those Zaph is using. He does have a notch filter on the tweeter. Does that resistance need to be included in the tweeter Re? Does it affect the values of the woofer cap and coil also?

I've done these comparisons with a couple other actual v. calculated crossovers. None of them agree.

Are these calculators of any value? Am I misusing them?

Thanks for any help!