Assistance required in rebuild of a focal crossover

[soundengine355]

Hey everyone!

I have an old focal speaker that I would like to rebuild the crossover with some higher quality components.

Attached are two pictures front and back

C1 - 3.3J 250V
C2 - 6.8J 250V
C3 - 18uF 63V
C4 - 33uF 63V

R1 - 7R1/7W (7.1 ohms / 7 Watts)
R2 - 10R/10W (10 ohms / 10 Watts)
R3 - 1R8/10W (1.8 Ohms / 10 Watts)

L1 - Unknown, need to test with multimeter
L2 - Unknown, need to test with multimeter
L3 - Unknown, need to test with multimeter
L4 - Unknown, need to test with multimeter
L5 - Unknown, need to test with multimeter

[soundengine355]

Any ideas what C1 and C2 capacitors are in uF?

[soundengine355]

Could someone help reconstruct the layout?

[soundengine355]

Worked out C1 and C2

3.3uF and 6.8uF

[jerome69]

Hello,

C1 and C2 are in uF. You can change C3 and C4 by film capacitors.
Don't change the inductors.

[soundengine355]

Looks like the resisters are ceramic, can they be changed to MOX?

[soundengine355]

Originally posted by jerome69
Hello,

C1 and C2 are in uF. You can change C3 and C4 by film capacitors.
Don't change the inductors.

Hi,

So I could not use Mundorf Mcap Supremes for C3 and C4?

Thanks.

[soundengine355]

Originally posted by soundengine355
Looks like the resisters are ceramic, can they be changed to MOX?

How would:

R1 7.1ohms/7W TO 1.5 + 5.6 ohm 20W MRESIST Supreme Resistor
R2 10ohm/10W TO 10 ohm 20W MRESIST Supreme Resistor
R3 1.8ohm/10W TO 1.8 ohm 20W MRESIST Supreme Resistor

[pjpoes]

adding resistors in parallel reduces resistance. Adding in series adds it, but also increases inductance (still typically quite small) and puts undo load on the higher value resistor. I wouldn't recommend this, just use the right value.

The electrolytic caps can be changed to film, but they will be huge, and may have a negligible effect on sound. They are probably in the woofer lowpass filter, and thus in parallel.

I know you won't probably do this, but I had a whole writeup on my rebuild of some focal speakers. An Electra Center and L-R speakers, and my rebuild found the greatest improvement by redesigning the crossover. Numerous measurements were taken of the individual drivers as well as the entire system both in a room and free space, as well as a lot of modeling. The final result was the largest single improvement I could have made. While changing the parts with better ones may make a difference, it's in the last .1% type change, where as changing the crossover was much more substantial. I fear you will invest a lot of money into upgrading parts only to find the improvement minimal if audible at all.

[soundengine355]

Originally posted by pjpoes
adding resistors in parallel reduces resistance. Adding in series adds it, but also increases inductance (still typically quite small) and puts undo load on the higher value resistor. I wouldn't recommend this, just use the right value.

The electrolytic caps can be changed to film, but they will be huge, and may have a negligible effect on sound. They are probably in the woofer lowpass filter, and thus in parallel.

I know you won't probably do this, but I had a whole writeup on my rebuild of some focal speakers. An Electra Center and L-R speakers, and my rebuild found the greatest improvement by redesigning the crossover. Numerous measurements were taken of the individual drivers as well as the entire system both in a room and free space, as well as a lot of modeling. The final result was the largest single improvement I could have made. While changing the parts with better ones may make a difference, it's in the last .1% type change, where as changing the crossover was much more substantial. I fear you will invest a lot of money into upgrading parts only to find the improvement minimal if audible at all.

Hi,

This is good to know, what Electra models do you have?

Thanks