Crossover help for the brain dead !

[julsie74]

Hi Guys
I'm new here with a knowledge of loudspeaker design that could happily fit onto the back of a postage stamp with plenty of room to spare ! So please be gentle with me.
Many years ago I built a kit from Focal, the Cristal 7, which has given me many years of pleasure. This year I decided to re-veneer the cabinets and thought while I'm at it maybe replace the drive units. After a touch of internet searching I came up with some possibilities, so here's my question:-
The old drive units are a Focal T90K and 7N515, can I replace these with the newer TC90TD5B and 7W4411 whilst using the same crossover and if not where would I be able to have a new one made for me? I live in the French Alps so Europe would be preferable. Many thanks for any help you may be able to give me.

[Loren42]

I really don't know the differences between those drivers, but what you want to look for is how well the Thiele-Small parameters match between the old and proposed replacements.

Also, a good match should have the same SPL levels, impedance curves, and polar responses at the crossover points.

Driver selection is not a trivial task and does require doing some home work to check that the replacement drivers match the original driver's parameters close enough to avoid replacing the crossover or at least minimizing changes to the crossover.

If the drivers are not a very close match, then you either have to modify the original crossovers or build a new crossover from scratch.

You can't buy an off-the-shelf crossover. Every speaker system requires a unique crossover for its application. The generic crossovers they sell at Part Express and other stores are not going to cut it.

The long and short of it is that for you to do this will require you to expand your knowledge beyond the postage stamp to possibly something spanning a few books. A lot will depend on how well the replacement drivers match the old drivers in the specification and parameter domain. However, as I said, this is not a simple problem and it will depend on how far down the rabbit hole you want to go.

[Inductor]

You can't use same X-overs, drivers are different.

FOCAL T90K
Impedenza Nominale: 8 ohms
Dimensioni: 92x92 mm
Diametro bob.mob.: 20.4
Sensibilita' 1w/1m: 91 dB
Potenza continua/programma: 10w/75w
Fs: 810 hz
Re: 6 ohms

FOCAL TC90TD5B
Impedenza Nominale: 6 ohms
Dimensioni: 60.90x53.90 mm
Diametro bob.mob.: 20 mm
Sensibilita' 1w/1m: 91.5 dB
Potenza continua/programma: 12w/75w
Fs: 1471 Hz
Re: 5.5 ohms

FOCAL 7N515
Manufacturer/ Dia. Power Z SPL Vas
Model RMS ohms 1W/1m Fs cu ft Qts xmax
7N515 7" 200W 8 ? 31Hz 1.85 0.207 0.21"

FOCAL 7W4411 (pic)
Go to X-over

[julsie74]

Ok, thanks guys
I'll pit them back together as they were.

[Inductor]

Originally Posted by julsie74

Ok, thanks guys
I'll pit them back together as they were.

If you later want to use them, or DIY, probably new box needs to be simulated also for the right interior volume with new woofer FOCAL 7W4411.
I showed you your new X-over for the new drivers on bottom of the page. Merci.

[julsie74]

Thanks for your info, I may use it later if I get braver !