Crossover Question

[SState13]

So I am about to undertake building my first set of speakers, a two way bookshelf using Aurasound NS6-255-8A woofers and Tang Band NS 25-302SH tweets. The drivers are already purchased, so using other drivers isn't really an option





I ran into a snag when I sat down to finalize values for my crossover, realizing that the Aurasound NS6 has significant impedance rise (or at least it seems significant to me) in the area of my intended crossover, I was hoping for around 2.5-3.5 KHz. The problem is that the manufacturer doesn't provide a value for inductance, so I can't really design a Zobel to compensate and I (most likely) won't have access to electronics equipment besides a voltmeter until I go back to school.

Link to manufacturers specs: http://www.madisound.com/catalog/PDF/ns6-255-8a.pdf

As of now, it seems that my options are:
1) design by the impedance value in the impedance-freq plot and hope that the impedance rise is gradual enough not to mess it all up
2) build the cabinets now and wait until i can get into an electronics lab at school to do some real measurements/ wait until I build another amp and go active
3) any other suggestions???

Thanks

[SState13]

Oh, one more thing, the sensitivity is listed at 91dB/1 Watt, however it is hard to tell where the markings are on the graph. if any of you could let me know what the SPL is at 1KHz (or any other frequency for reference), that would be awesome, and very helpful for adjusting the level on the tweeter

[PeteMcK]

there's a 'rule of thumb' calculator here: Passive Crossovers, Zobel Calculator
That'll get you in the ball park, I don't really think a zobel is necessary for this driver if you calculate the crossover using the impedance values at the crossover freq.

You can measure Le quite easily: Download ARTA: ARTA ARTA Download, Make this simple jig: ARTA Jig - AudioBlog: A simple loudspeaker measurement jig for ARTA

[SState13]

That ARTA jig looks like a great idea, although I'm not entirely sure how its wired. From the computer output, is only the positive lead used to provide a voltage to one end of the resistor/resistor+speaker, with the computer input receiving the signal from the negative side of the resistor/speaker?

if you have built one of these, do you have a picture of it all wired up?