Focal seperates

[seankane]

Hello everyone.

A customer has brought me a set of 6" focal midranges and 1" focal tweeters.

He also has brought no cross overs.

The 6" I am not so worried about. The tweeters I am worried about.

Can anyone tell me what kind of cap to run inline with the tweeter?

I am assuming bi-polar, axial, and in the 4mfd 50v range? Wired inline with the positive tweeter lead? Just a guess?

I don't want the tweeters to blow.

Should I run a resistor inline as well to limit the power?

[ultra]

A cap in the range of 2.2μF to 4.7μF will do.

The bigger the capacitance, the lower the operating frequency.

Its a matter of taste.

But a simple capacitor forms a 6 db slope filter.

[RiLoWa]

Without knowing the model number, I friend of mine has some Focal components and it high passes the tweeter at 4KHz. I'm not sure about the slope, I bet it is at least 12dB though. Most Focal tweeters I have seen don't like low crossover points.

[Jay]

Originally Posted by seankane

Can anyone tell me what kind of cap to run inline with the tweeter?
I am assuming bi-polar, axial, and in the 4mfd 50v range? Wired inline with the positive tweeter lead? Just a guess?
I don't want the tweeters to blow.
Should I run a resistor inline as well to limit the power?

The tweeter is crossed at certain frequency according to the natural roll-off of the woofer. This mandates a certain value of capacitor. A little variation to the capacitor value is possible to get the best overlap.

This capacitor value is calculated after you decide the value of the series resistor. So the cap and the resistor should be seen as a combo.

The resistor is not to protect the tweeter. It is added so the tweeter is not louder than the woofer. Then the capacitor value is determined after the resistor value has been decided.

You protect the speaker/tweeter by using amplifier power not too high in power relative to tweeter power capacity (Too low amplifier power may also dangerous if driven to clipping while the design doesn't allow it to be driven to clipping).

The capacitor in series with the tweeter will naturally protect the tweeter from DC. Too much power is what you should avoid. Easier if the amplifier power is no more than half of the tweeter power handling capacity. But usually this is determined by woofer power handling which usually is lower than tweeter power handling capacity.

Yes, the cap is usually connected right on the positive pin of the tweeter. With such a simple crossover, and relatively expensive drivers, people usually use better than axial bipolar cap. MKP is the minimum standard. Some even use exotic cap here.

ADD: Pay attention to your amplifier power, compare it to your friend's.

[TheBaronGroog]

Focal usually list the x-over freqs of their sets on their site-what's the model?

Does he not want to run them active and use processor/amp crossovers instead of passive ones?

[seankane]

Thanks for all the info guys, very helpful.

I will post the model of the mids and tweets.