Crossover for Vifa XT25SC-90/04

[giralfino]

Hi, I'm planning to build a 3 way using the Vifa XT25SC-90/04 as a tweeter.
Reasons for this tweeter are a decent performance (as per Zaph), a small flange and availability here in Europe.
What bother me is the strong impedance peak at resonance (837 Hz). I'm planning to cross it at around 3K5 with a second order filter (maybe 6.8 uF + 0.15 mH). It is enough? or do I have to flatten (how?) the impedance peak?
TIA, Ralf

 

[Michael Chua]

Hi Ralf

The Vifa XT25SC-90/04 is a good tweeter. The high resonance is a limitation though. I cross my XT25 at 3K5 at 18dB. Very clean, no problem. Can't go lower than that unless I use a LCR to damp the Q.

I just finished a 2-way monitor using this XT25 with Zaph ZA14. Details are in my website.

Regards
Mike

 

[giralfino]

Hi Mike,
for LCR you mean this?
Are there better calculators?
Thanks, Ralf

 

[Michael Chua]

Yes, that's the one. A Series Notch Filter. It's quite effective to dampen tweeter resonance.

I think you will be alright with 12dB at 3K5. I don't use 12dB for tweeters because of phasing issues with my woofer which is at 12dB. So my tweeter is either 18dB or 24dB.

FRD has very good software (free). Download Jeff Bagby Passive Crossover Design Calculator. Excellent for speaker design. Series Notch is on the 3rd page.

 

[giralfino]

Mike,
I forgot to thank you for the info.
I will give the Passive Crossover Design Calculator a try, even if I already use the Passive Crossover Designer from the same author.
Ralf

 

[portreathbeach]

I know this is an old thread, but if I wanted to use this tweeter as a 'super tweeter' with my full range CSS EL70, could I ignore using a notch filter if I were to use a crossover around 8K Hz?

Cheers

 

[Michael Chua]

Yes, go ahead without the LCR notch. Start off with a capacitor and a resistor.

If you can pick out the tweeter resonating, then apply the LCR.