10 replies to this topic

[halo99]

hey guys,

im about to setup my system this weekend in an active crossover system using the Alpine PXA-H100 going to Focal 165KR & Scanspeak XT25.

this is the first time ive done any crossing over on higher frequencys and after a little guidence.


what would you reccomend the frequence cut should be beween the mids and the highs? how steep of a roll off should i be using?

just after somewhere to start, i know it's going to be alot of trial and error.

ive included the driver info's below, any recommendations?

Focal -
http://www.focalaust...fs/k2_165KR.pdf

Scanspeak-
http://www.tymphany.com/xt25tg30-04

[br85]

Start with 3khz as a ballpark figure.

I'd recommend 24db/oct on the tweeter and 18db/oct on the mids, to start with. Before deciding whether you like that or not, drastically alter the tweeter gains (usually they're way too hot at first, you've gotta gain match).

[Winno]

br85, on 20 May 2010 - 07:43 PM, said:

Start with 3khz as a ballpark figure.

I'd recommend 24db/oct on the tweeter and 18db/oct on the mids, to start with. Before deciding whether you like that or not, drastically alter the tweeter gains (usually they're way too hot at first, you've gotta gain match).

+1 to that.

At this stage I have left my system to run at the Clarion HX-D2 defaults with xover point of about 2.5k and 12dB slopes and it seems to work well for now. I'll play with things more though once my midbasses are powered up again...

[mrock]

What's the Fs of the Tweeter?

[br85]

mrock, on 21 May 2010 - 08:44 AM, said:

What's the Fs of the Tweeter?

depending on which XT-25 you have, it could be 500-800hz. Don't let that fool you, though, you can't cross these things below 2khz without a waveguide, the harmonic distortion is extremely painful to listen to.

In Zaph Audio's Tweeter Mishmash, he describres the big XT-25 like this:

"Smoothest and most extended response curve in the group, and resulting CSD is excellent. Good tall order HD above 2kHx, but average 2nd order HD. Poor HD levels of all types below 2kHz, even considering the extended low end. It may have a 500 Hz Fs, but don't think about crossing it below 2kHz LR4 or 2.5kHz LR2. Off axis response curves available. Tested January 2006."

And the small (neo motor) XT-25, this:

"Smooth response except for a mild peak at 4kHz with a small bit of ringing in the CSD. Decent harmonic distortion performance for neo tweeters in this group. Recommend 2.5kHz LR4 0r 3kHz LR2 xover points. Performs well but not equal to it's larger brother. Tested April 2006."

I should point out that many speaker builders think these tweeters perform MUCH better active than passive (something to do with inductance from a passive) so you should get great results (as long as you install them on axis.)

Edited by br85, 21 May 2010 - 08:54 AM.

[mrock]

For a generaal rule of thumb, it is usually around 3x the FS Frquency.

[br85]

mrock, on 21 May 2010 - 09:25 AM, said:

For a generaal rule of thumb, it is usually around 3x the FS Frquency.

I've heard 2x, or 3x, before, but after working with quite a few different drivers I've thrown "rules of thumb" out the window, and my crossover points are usually based on MUCH more data than just fs. Distortion plots, xmax, polar response of the next driver down all play a role in determining crossover points. Also, when going active, you can't be afraid of EQ, since it usually comes in the same unit.

[mrock]

fair enough

[halo99]

awesome

thanks for the advice, got a whole weekend free to test

they are the Big XT's (next step is to try and find a way to install em, looks like the only place i could fit them and be on axis is on the dash/A pillar so i hope the distance between the woofers and tweeters won't cause too much of an imaging problem)

[br85]

halo99, on 21 May 2010 - 02:01 PM, said:

awesome

thanks for the advice, got a whole weekend free to test

they are the Big XT's (next step is to try and find a way to install em, looks like the only place i could fit them and be on axis is on the dash/A pillar so i hope the distance between the woofers and tweeters won't cause too much of an imaging problem)

It shouldn't cause major problems (that most people can hear, anyway). They get quite a bit smaller if you get out your allen key set and remove the flange. Gives you about an extra inch of room to play around.

[halo99]

br85, on 21 May 2010 - 02:41 PM, said:

It shouldn't cause major problems (that most people can hear, anyway). They get quite a bit smaller if you get out your allen key set and remove the flange. Gives you about an extra inch of room to play around.

yeah i was thinking the exact same thing but still quite large, i can smell some fiberglass coming