The idea isn't to cover a hole from the midhorn or any other driver, it's to make the first octave flat when a bypassed attenuator is used to increase HF. If you added HF-bypassed padding like that withgout slightly underdamping the crossover, the resulting curve would be a diagonal line starting at the crossover frequency and rising straight away. We don't want output to start rising for an octave, so we peak the bottom of the curve just a smidge, in order to provide a response curve like shown below:

Like you, I designed the circuit with Spice. It allowed me to model the compression driver/horn with voice coil resistance/inductance and a series of resonators. I was able to make a very good model that gave accurate results. But by including actual impedance measurements of the driver, I've been able to get even just a little bit closer.

• Spice models using ZMA files

I found the same thing you did, that my crossovers had a smidge more peaking than I wanted. Your chart is very close to what I've seen. It isn't objectionable, but I changed values as a result. Reducing C2 a little and increasing the size of L1 made an improvement.

I'm not concerned about shifting the -6dB frequency by a couple hundred Hertz, in fact, the crossover has always been asymmetrical anyway. They're sloped filters, not brick wall filters, so in-band and out-of-band signals are separated by a relatively large overlap region. That's a grey area, so to speak, in that acoustic summing between drivers is in play, not just electrical slopes. Even if it appears that one crossover point is a few hundred Hertz different than the other, the only thing that matters is that summing results in a nice flat response curve. That's where the rubber hits the road, so to speak.

I have downloaded your .zma files, but where do I put them in the Spice dir. ?

When I try to do a simulation I get this error:

Circuit: ! Seven Pi mid/tweeter crossover Spice model
Error on line 34 : z1 1 0 h290_psd2002.zma 0 0
unable to find definition of model 0 - default assumed
error: no unlabeled parameter permitted on mesfet
Error on line 62 : z2 7 0 sevenpi_midhorn.zma 0 0
unable to find definition of model 0 - default assumed
error: no unlabeled parameter permitted on mesfet

And how do you make the phase simulation you talk about in your crossover white paper ?'

Regards
Kim

You can calculate electrical phase with vectors. Here's a write up of the process, with real-world examples and models in Spice:

• Vector calculations for AC analysis

Can you give me the new component values for the crossover, then I´ll try it out and make some new measurements tomorrow.

What is the sonic difference between the old and the new crossover ?