Why don't you fix the original crossover? You should duplicate the original circuit to make the speaker work properly.
The original crossover has 2 resistors, one 5ohm potentiometer (variable voltage divider) and a fixed resistor. You could "simulate" the mid position of that attenuator using 2 fixed resistors. you could use something close to 2.5ohm, or a 2 ohm and a 3.3 ohm, choosing at which side you want the 3 ohm, and which side the 2 ohm. I guess you can use the original 9.4 ohm resistor if you still have it. One or 2 tenths of an ohm won't make a difference in this application.
Forget about online crossover calculators and xover points. If you are using the original midrange driver, copy the original crossover values.
Restoring the original xo with upgraded caps is now my long term plan. It's stapled in place, so I'm a little leery removing it without damaging anything. Also, I would like to keep the potentiometers for flexibility. 5ohm ones don't exist anymore. So, I figured a solution would be to eliminate the fixed resistors, and just use 8ohm potentiometers. I could be wrong, but you should be able to get the sound level you want from the mids and tweets since pots are adjustable. You would just need adjust the cap and coil values to maintain Infinity's original crossover points.
It has been a long journey. When I bought these speakers, the original woofs were long gone, and replaced with $17 Goldwood's from PE. According to Infinity's original literature, the forward firing woof was designed to act as a midwoofer, and the downward firing one was doped to act as a sub. Since the OE drivers are nonexistent, I put a decent 4-ohm sub in the bottom, use the original 4.3 mH coil to cross it over way low. Then, install a PRV 10MB400 on the front, crossing it over with a ready-made PE 800hz 2nd order butterworth low pass from PE. Unfortunately, the PRV's 97db SPL was still way too much. Then, one of the original mids blew, and the mid section of the original xo also quit working. So, I decided to "upgrade" bought a pair of dome mids from Mavin, crossing them over with a 1st order PE 800hz-5khz bandpass. Their performance was meh, they drowned out the highs. So I then put some more efficient palnar (similar to HiVi RT1C-A but 8 ohm instead of 6) to compensate. Still sounded terrible.
It was only then that I FINALLY made the correct decision to get things back to as original as possible. So, started by purchasing a pair of the OE Phillips mids. Top tip: They are all 8ohm even though most of them were used in 4ohm Infinity designs. If I had known that, I would have NEVER tried to replace them with something different. I then paralleled the 2 woofs into the original 4.3mH coil, which creates a 6ohm load, and crosses them over at 225hz. That seems to tamed the PRV, and fixed the woof/mid relationship. However, I can't tell for sure because the upper mid is so loud. Building my proposed bandpass should give me the data that I need. Since I don't have and can't get the original woofers, rebuilding the original xo to the exact factory spec might not be what's best. A little trial and error is needed to figure a few things out.
This may have been a long-winded explanation. I hope someone facing a similar situation will read this, not make the same mistakes, and spare themselves from the frustration that I experienced.
