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cross over [message #51874]

Thu, 06 March 2008 08:55

Roland Gama
Messages: 38
Registered: May 2009

Baron

Hello Wayne,
The 12Pi is nearing completion and will post pics when its done.

Taking the 12PI and the 4Pi (JBL 2226/ DE 250) and crossing it over using the Behringer DCX2496 digital crossover what would the preferred crossover points for the sub, mid and highs? Also what would the preferred slopes and order?

Roland.

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Re: cross over [message #51875 is a reply to message #51874]

Thu, 06 March 2008 11:42

Wayne Parham
Messages: 18786
Registered: January 2001

Illuminati (33rd Degree)

I would crossover to the subs somewhere between 70Hz and 100Hz. The frequency and slope will depend on the environment, the configuration of speakers and the position of each of them. Assuming you're using one or two four π speakers right above a single 12π hornsub and your environment is very large or outdoors, then I'd crossover the four π at 90Hz and the 12π at 70Hz, fourth-order slope on both. Sounds like there would be a hole but there's not because even fourth-order is not a brick-wall filter. Be sure to delay the signal sent to the four π speakers by 8mS. If you use a pair of four π speakers, stack them vertically with the tweeters together and woofers outboard, like an MTTM configuration.

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Re: cross over [message #51876 is a reply to message #51875]

Thu, 06 March 2008 11:57

Chris R
Messages: 133
Registered: May 2009

Master

Wayne,

>> If you use a pair of four π speakers, stack them vertically with the tweeters together and woofers outboard, like an MTTM
>> configuration.
So often I see 2 and 3 way speakers at shows stacked like there was only one.
It always makes me wonder about those that set them up.
Chris

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Re: cross over [message #51877 is a reply to message #51876]

Thu, 06 March 2008 14:01

Wayne Parham
Messages: 18786
Registered: January 2001

Illuminati (33rd Degree)

When using a pair of four π speakers, I think it makes sense to stack them with midwoofers outboard above and below, i.e. MTTM. That's better than MTMT, which would leave too much distance between tweeters.

For larger installs, a modular line array approach would probably be better, with a square mouth tweeter on one side and a woofer on the other, both being approximately the same size. When vertically stacked, they form a line of closely spaced midwoofers and a line of closely spaced tweeters. That's basically a four π on its side, using a different tweeter appropriate to the orientation and application.

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Re: cross over [message #51881 is a reply to message #51875]

Fri, 07 March 2008 00:06

Roland Gama
Messages: 38
Registered: May 2009

Baron

Thanks Wayne.
Need a little more on that.
Consider the speakers to be a pair of 12pi, JBL 2226 and DE250 without passive crossovers.

Then how do I cross this three way system using an electronic crossover (DCX 2496) in terms of
1) Crossover points
2) Alignments and
3) Slopes ?

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Re: cross over [message #51882 is a reply to message #51881]

Fri, 07 March 2008 11:21

Wayne Parham
Messages: 18786
Registered: January 2001

Illuminati (33rd Degree)

Crossover the four π high-pass at 90Hz and the 12π low-pass at 70Hz, fourth-order (24dB/octave) slope on both. The four π crossover is third-order (18dB/octave) for both woofer and tweeter. The midwoofer crossover point low-pass is 1300Hz and the tweeter crossover high-pass is 1600Hz. Add CD equalization for the tweeter, ideally with a curve like shown below: