Peerless HDS 830860 with XT25SC90-04 or DQ25SC05-04

[Jimmy154]

Which tweeter is a better match for the Peerless HDS 830860?
http://audiokit.it/ITAENG/Altoparlan...sDK/830860.pdf
http://www.tymphany.com/files/resour...Q25SC05-04.pdf
http://www.tymphany.com/files/XT25SC90-04%20Rev1_0.pdf

I'm going to use them in my car kick panel. With the XT25 I would cross it over at ~3000 Hz and the DQ25 around 2000 Hz, both with a cap and inductor. I would want the DQ because it can be crossed over lower without distorting as much as the XT would, giving the woofer great off-axis frequency response. But I also would want the lower distortion numbers the XT has above 3000 Hz and good off-axis frequency response the XT is known for. Which brings me to my main question: why is the XT known for good of axis frequency response (if in fact it is known for this) when the frequency response graphs show that the DQ has better off axis frequency response? Which tweeter would be a better choice and at what cross-over frequency? The XT loudness level on-axis is flat to 40000 Hz, but who wants or needs that?

[Jimmy154]

I bought the XT25's. What finally changed my mind was seeing the pink noise power handling of the DQ25 was 25% of the XT25's and the long term max power was 80% of the XT25's. It relied on ferrofluid to cool it's voice coil. Which at first I didn't realize (until I saw the power specs) that this probably meant it either had poorer voice coil cooling or a thinner voice coil wire.

[Jimmy154]

The decision I'm having some trouble with now is whether to cross the drivers over (2nd Order Linkwitz-Riley) closer to 2 KHz or 3 KHz. I don't know whether it's more important to have great off-axis frequency response, given that the drivers will be in my car kick panels, or whether it's better to cross the tweeter over at 3 KHz to avoid the distortion below this point. Any one have an opinion on this?

[Jimmy154]

I'm trying to make a series notch filter for the XT25SC90-04 tweeter and I'm not sure how far I can deviate from the values a series notch filter calculator gave me. Also I don't know what kind of capacitor to use. Here is what it gave me for the values I put in:

Series Notch Filter

Re = 3.2 Ohms

fs = 825 Hz

Qes = 1.07

Qms = 7.2


Parts List
Capacitor
C = 56.36 uF
Inductor
L = 0.66 mH
Resistor
Rc = 3.675555555555556 Ohms

[Jimmy154]

I think I might know what the values do in the circuit, but I don't know what kind of capacitor I should use and at what the voltage rating has to be.

[wolf_teeth]

If you xover high enough, the SC90 will only require a 30 ohm resistor across it to eliminate the buzzing Fs spike.
Later,
Wolf

[Jimmy154]

Thanks for the advise Wolf. Wouldn't that attenuate it quite a bit? I crossed it over at 3 KHz with a 2nd order LR.

[kmibb]

Peerless HDS PPB 830860

[Jimmy154]

I saw that cross over, but it is for a XT25TG-30-04. Also some of it didn't make sense to me, well most of it, but especially why there is a series notch filter on the woofer. I don't know how to modify the tweeter crossover(or simplify the woofer crossover) for use with my tweeter. Specifically it has an fs for 825, not 500 Hz. Upon closer inspection, I notice that the fs of my tweeter should not change the crossover function, but I would still like to leave the series notch filter out of my woofer crossover, if possible. Is it possible?

[Jimmy154]

Looks like the series notch filter on the woofer is a baffle-step compensation circuit, since it seems to attenuate frequencies from 250 Hz to 2500 Hz. I think I will leave the baffle-step circuit out, if that's what it is. What function does the .2 ohm resistor wired above the 10 uF capacitor on the woofer serve? I would like to replace the resistor and cap with a 8 uF cap or even as high as 10 uF. Does the .2 ohm resistor make the cap function more properly as the impedance of the woofer rises near the crossover point?