Will a 47uf 100 volt cap block 100 hertz

The capacitive reactance of a 47uF capacitor is 33.86 Ohms at 100 Hertz.

Capacitive reactance = 1/(2*pi*frequency*capacitor value)

Almarg

Oops! brain fart, thanks for the heads up, too late to swap.

Cheers George

I agree with George's calculations, except that he inadvertently interchanged "56" and "224" (or "15" and "60").

Be sure, of course, to choose a non-polarized capacitor.

Regards,
-- Al

It all depends what load to ground (speaker impedance) this cap sees.

A 47uf in series will have to see a load to ground after it of 30ohms to be -3db at 112hz.

If the load is 15ohms to ground then it's -3db at 56hz.

If the load to ground is 60ohms then it's -3db at 224hz.

For yours
If the load is 8ohms and you want -3db at 100hz you need a 200uf series cap.
If he load is 4ohms then you need 400uf.

Cheers George

If the Gallo is 4 ohms you'd need apx 400Uf for a first order 100HZ crossover and 200uF if they are 8 Ohms

Best of luck

Peter