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passive crossover point [message #23888] Wed, 18 July 2007 23:00 Go to next message
zobsky is currently offline  zobsky
Messages: 39
Registered: May 2009
Baron

I thought I'd ask here before I order the parts for the crossovers.

I plan to cross my 12 x 5.25" foster midwoofer line to the `49 x 1.125" apex jr tweeter (Fs between 3 - 3.5KHz) line around 5 KHz because the drivers match each in sensitivity around there. Not quite meeting the 1/2 wavelength or 1 wavelength criteria but I don't think I have a choice for a passive crossover.

Any suggestions on this point of crossover.
Also, I thought about notching out the broad hump below 1KHz but the capacitors needed for a series notch filter at those frequencies are pretty costly. Any thoughts on this?


Re: passive crossover point [message #23889 is a reply to message #23888] Wed, 18 July 2007 23:03 Go to previous messageGo to next message
zobsky is currently offline  zobsky
Messages: 39
Registered: May 2009
Baron
Forgot to mention, I'm thinking of 3rd order butterworth (tweeter line impedance is pretty much a flat 6 ohm, while the woofer line will need a zobel to hold it steady at 6 ohm)

Re: passive crossover point [message #23895 is a reply to message #23889] Mon, 23 July 2007 08:28 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18695
Registered: January 2001
Illuminati (33rd Degree)

When I measured Fred Thompson's ART Arrays, I expected a high-order crossover would be better. As a general rule, I think one can expect this. But in the case of the ART Arrays, they measured better with a simple first-order filter on the woofer array and the tweeter.


Re: passive crossover point [message #23896 is a reply to message #23895] Mon, 23 July 2007 12:15 Go to previous messageGo to next message
zobsky is currently offline  zobsky
Messages: 39
Registered: May 2009
Baron

Thanks for all the help, Wayne.

Last week, I used foobar 2000's DSP filter plugin to test various filter types / x-over points and slopes . There didn't seem to be much difference (if any) between a 4KHz and 5 KHz point, so I picked 5KHz as the higher x-over point allows the tweeters to play louder with less distortion.

I've ordered parts for a 5KHz / 3rd order filter and a zobel ciruit for the open baffle woofer array . Rather than use a passive filter to tame the mid-bass / mid-range hump, I plan to use the eq. in foobar 2000 for this purpose, if I eventually find it an issue. The tweeter impedance peak is fairly benign (2 ohm above the nominal 6 ohms).

Almost there.

Re: passive crossover point [message #23897 is a reply to message #23896] Tue, 24 July 2007 11:51 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18695
Registered: January 2001
Illuminati (33rd Degree)

Very cool!


Re: passive crossover point [message #23901 is a reply to message #23896] Wed, 25 July 2007 12:35 Go to previous messageGo to next message
Marlboro
Messages: 403
Registered: May 2009
Illuminati (1st Degree)
You may not have to tame anything. One of the characteristics of ganging multiple speakers together is that the the FR's tend to smooth down to a common flatness.

I electronically crossed my system (http://pub48.bravenet.com/photocenter/album.php?img=115732&usernum=4095425731)
and purchased a 2/3 octave crossover to tame certain aspects. I took it out of the circuit since its just not needed.

Marlboro

Here's the output with the crossover and zobel in place [message #23904 is a reply to message #23896] Fri, 27 July 2007 19:07 Go to previous message
zobsky is currently offline  zobsky
Messages: 39
Registered: May 2009
Baron

I'm satisfied with the result. Thanks, all.

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