Completely stumped on this filter type, need help.

ridikas

Member
2011-11-25 9:16 pm
Need Help to Understand This Very Strange Crossover!

This crossover is from an old set of custom Focal driver based speakers. I'm especially baffled on how the tweeter's network works. Is this an elliptical/Cauer filter? Any of you gurus know what frequency this might be crossing the tweeter at?

Thanks for all of the help and any insight/discussion on this beast is greatly appreciated. Never really seen anything like it...
 

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ridikas

Member
2011-11-25 9:16 pm
Tried asking in the loudspeaker forum, but maybe I'll have better luck here. This is from an old custom made Focal based speaker. I'm particularly interested in solving the tweeter's filter type and function. Is it some sort of Cauer filter?

Can any of you gurus approximate at what frequency the tweeter is crossed? Any insight/discussion will be greatly appreciated.
 

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ridikas

Member
2011-11-25 9:16 pm
Here is the LF response with a generic 5R load, I think it is not a Cauer filter, since the passband has no ripple to speak of... but the stop band looks very messy, wonder what Focal was thinking.:confused:

View attachment 547033

Very interesting! Are you able to model the tweeter and the midrange/mid woofer? Tweeter is 7.4 Ohms, midrange/midwofer is 6.4 Ohms. Just for kicks...
 
A speaker is not a simple impedance it always have peak & dip and phase shift...

So simulating cross over with resistive load will never give the exact result

I this desing I think they also made some kind of equalisation to compensate drivers response .. or enclosure .... this make the circuit even more difficult to figure out ...
 
Completely demented design that I hope you are not plugging into your expensive amplifier, because it is an amp killer! :eek:

The tweeter filter is some hopeless implementation of a KEF Acoustic Butterworth, with an Fs notch from the snubbing 0.33uF capacitor at 1.2kHz.

There are undamped notches all over the place. Without knowing what the drivers are, it is hard to say what this designer was thinking of. He needs help. :D
 

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