two 8 ohm widerange drivers in array+ 4 ohm tweeter:is it possible?

[Peters8]

Hi guys!
I've a pair of old italian boxes, with two Faital 8 ohm fullrange drivers connected in parallel in order to get 4 ohm, for each plastic case
You can see them in the picture below.
They sound very fine but I miss a tweeter in their sound.
So I want to build two wooden cases to mount them into...but I would to add also a tweeter in every case.
I've two old paper Faital 4 ohm tweeters and I would to use them.
Well my question is: can I use in each case those 4 ohm Faital tweeters with two 8 ohm fullrange drivers connected in parallel? Of course I should add two capacitors in series to the tweeters.
I apologize for my ignorance
I hope you can help me!
Thank you in advance for your patience
Regards

 

[Galu]

Yes, you can add a 4 ohm tweeter to your two paralleled fullrange drivers.

If you can give details of your drivers, you may get help with the crossover.

If not, a 4uF non polar film capacitor would be a good starting point for experiment.

 

[rayma]

can I use in each case those 4 ohm Faital tweeters with two 8 ohm fullrange drivers
connected in parallel? Of course I should add two capacitors in series to the tweeters.

Along with the capacitor, you may also need a series resistor if the tweeter is too loud.
If so, that will affect the value of the capacitor needed.

 

[Peters8]

thank you guys!

 

[Peters8]

Guys just a last question, please: does the total impedance value of the 2 paralleled fullranges+ the tweeter remain 4 ohm? thank you again for your precious help.
Regards

 

[rayma]

does the total impedance value of the 2 paralleled fullranges+ the tweeter remain 4 ohm?

The system impedance will be 4 ohms up to the crossover frequency.
Above that, it may be lower, depending on how the woofer's impedance
rises with frequency, and on the value of the tweeter pad resistor.

Worst case is that the system impedance drops to 2 ohms above the crossover
frequency, with no pad resistor, and with the woofers keeping a flat impedance curve.
Usually though, a woofer's impedance will rise at higher frequencies.
You also will very likely need a series resistor in line with the tweeter to match the levels.

 

[Peters8]

Thank you dear Rayma...I wouldn't add any resistor to the tweeter...its sound isn't loud at all (it reaches just 15.000 hZ).
I'll just add a 10 uF capacitor in series to the tweeter.
Now if you tell me that the total impedance could drop to 2 ohm...that could be a serious problem.
I'm a bit confused...
Anyway thank you again for your time and your kind help.
Regards

 

[rayma]

Now if you tell me that the total impedance could drop to 2 ohm.

Above the crossover point, possibly.

 

[Sonce]

Now if you tell me that the total impedance could drop to 2 ohm...that could be a serious problem.

Not likely.
Don't worry. Start with 4.7 microF capacitor in series with the tweeter..

 

[Galu]

The system impedance may be regarded as a nominal 4 ohm.

A 10uF capacitor is too much.

Using a 3.3uF or 4.7uf will pass the upper frequencies missed by the 'full range' drivers while protecting the tweeter from bass overload.

 

[JMFahey]

Yes, those light speakers already reach quite high, they only need "help" from the tweeters, plus simple 1 capacitor slope is shallow, so 4 or 4.7uF as suggested above is fine.

10uF will make their output superimpose too much with current speakers, you don´t need that, plus send more RMS power to tweeters, you don´t want that either.

Those Faital must be old, back when they made car speakers and such, before the current PRO type products.

 

[Peters8]

Thank you dear guys for your precious support!
My old Faital paper cone tweeter was originally mounted in a bass reflex box with a doble cone Faital fullrange and it was filtered by two polarized 25 uF capacitors (in order to get a no-polarized capacitor).
So the original capacitor uF value was 12,5 uF.
Anyway, I'll do some experiment with the capacitors value, before choosing the the definitive one.
Thank you again for supporting me
Best regards, my friends!

 

[Galu]

Thanks for the feedback. Perhaps you'll let us know how you get on.

 

[Peters8]

Thanks for the feedback. Perhaps you'll let us know how you get on.

Oh yeeesss...of course!
Regards