I thought I understood crossovers ....

MrUnsocial · 17th July 2005, 07:58 AM

going from a 6db/octave butterworth lowpass @ 3200Hz to a 12db/octave chebychev @ 3200Hz made the midwoofer brighter, alot brighter.
I thought it would have cut out more of the higher frequencies not let more pass, what gives?
reason for going from butterworth to chebychev was that's what parts I had lying around to play with atm. same coil but added a 12uf cap.

richie00boy · 17th July 2005, 09:16 AM

Maybe phase response causing summation of some frequencies?

Jonathan Bright · 17th July 2005, 09:54 AM

Is it possible to see the xover diagram? I think Chebychev have some ripple in the pass band don't they? If you got a few db peak around 3k Hz where the ear is sensitive you could well get a "brightening".

rabbitz · 17th July 2005, 12:57 PM

With using the Chebyshev, you're getting a summing at the crossover frequency of around 6dB. If you want to use that crossover, don't crossover the woofer and tweeter at the same frequency. You'll get better summing by crossing over to the woofer lower and the tweeter higher by a factor of around 1.5.

So the woofer is calculated at 2133Hz and the tweeter at 4800Hz to give the best summing at 3200Hz.

Odd choice of crossover... any reason you went away from the 1st order and went for the 2nd order Chebyshev? Just curious and not being nasty.

MrUnsocial · 17th July 2005, 04:20 PM

here are the screencaps of harris tech x-over 2.0 I used to design these x-overs ....

I went from 1st order bw to 2nd order cc cause that's what parts I had lying around to play with until I order some new parts for a 24db/octave lr x-over. After listening to this 1st order bw for a while, I might just order some good parts for it and leave it like it is, sounds pretty nice.

Madmike2 · 17th July 2005, 04:27 PM

After 2 weeks of daily banging my head off a wall, i can tell you to measure and build those passives for your drivers exact impedance dude. They will not be the same at all if you tell it generic drivers.

Mr Evil · 17th July 2005, 04:46 PM

Attached is what the ideal frequency response of your Chebychev crossover looks like. The filter sections have very high Q, hence the large peaks. It's preferable to use Butterworth, Bessel or LR to avoid such peaks.

carlosfm · 17th July 2005, 04:52 PM

That's right, Chebychev filters have ripple in the crossover region.
Before it goes down, it goes up.

Not what I would use on a speaker...

MrUnsocial · 18th July 2005, 12:18 AM

I forgot to mention the fact that the tweeter wasn't hooked up during the test, I just wanted to see what effects the crossover had on the woofer. Seemed to remove some bass and let alot more treble through.

Madmike2 obviously you've never used x-over 2.0 ... I just put in "generic woofer and tweeter" for the name, specs are correct, just did that quick for the screenshots.

Madmike2 · 18th July 2005, 12:25 AM

I C no i never used it. Just assumed from the screen shot that it automatically assumed car audio spec 4 ohm drivers. Which you know as well as i will not be even close

17th July 2005, 07:58 AM	#1
MrUnsocial diyAudio Member Join Date: Feb 2002 Location: Phoenix AZ	I thought I understood crossovers .... going from a 6db/octave butterworth lowpass @ 3200Hz to a 12db/octave chebychev @ 3200Hz made the midwoofer brighter, alot brighter. I thought it would have cut out more of the higher frequencies not let more pass, what gives? reason for going from butterworth to chebychev was that's what parts I had lying around to play with atm. same coil but added a 12uf cap.

17th July 2005, 09:16 AM	#2
richie00boy Did it Himself diyAudio Member Join Date: Nov 2003 Location: Gloucestershire, England, UK	Maybe phase response causing summation of some frequencies? __________________ www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more

17th July 2005, 09:54 AM	#3
Jonathan Bright diyAudio Member Join Date: Feb 2004 Location: Queensland	Is it possible to see the xover diagram? I think Chebychev have some ripple in the pass band don't they? If you got a few db peak around 3k Hz where the ear is sensitive you could well get a "brightening". __________________ "It was the Spring time of the year when aunt calls to aunt like mastodons across the frozen waste." P.G. Wodehouse.

17th July 2005, 04:27 PM	#6
Madmike2 diyAudio Member Join Date: Apr 2005 Location: Toronto	After 2 weeks of daily banging my head off a wall, i can tell you to measure and build those passives for your drivers exact impedance dude. They will not be the same at all if you tell it generic drivers. __________________ Persistence is better then intelligence. Unless persistence kills you.

18th July 2005, 12:25 AM	#10
Madmike2 diyAudio Member Join Date: Apr 2005 Location: Toronto	I C no i never used it. Just assumed from the screen shot that it automatically assumed car audio spec 4 ohm drivers. Which you know as well as i will not be even close __________________ Persistence is better then intelligence. Unless persistence kills you.


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17th July 2005, 12:57 PM	#4
rabbitz diyAudio Member Join Date: Jul 2003 Location: Newcastle, Australia	With using the Chebyshev, you're getting a summing at the crossover frequency of around 6dB. If you want to use that crossover, don't crossover the woofer and tweeter at the same frequency. You'll get better summing by crossing over to the woofer lower and the tweeter higher by a factor of around 1.5. So the woofer is calculated at 2133Hz and the tweeter at 4800Hz to give the best summing at 3200Hz. Odd choice of crossover... any reason you went away from the 1st order and went for the 2nd order Chebyshev? Just curious and not being nasty.

17th July 2005, 04:20 PM	#5
MrUnsocial diyAudio Member Join Date: Feb 2002 Location: Phoenix AZ	here are the screencaps of harris tech x-over 2.0 I used to design these x-overs .... I went from 1st order bw to 2nd order cc cause that's what parts I had lying around to play with until I order some new parts for a 24db/octave lr x-over. After listening to this 1st order bw for a while, I might just order some good parts for it and leave it like it is, sounds pretty nice.

17th July 2005, 04:52 PM	#8
carlosfm Banned Join Date: Mar 2003 Location: Lisbon, Portugal	That's right, Chebychev filters have ripple in the crossover region. Before it goes down, it goes up. Not what I would use on a speaker...

18th July 2005, 12:18 AM	#9
MrUnsocial diyAudio Member Join Date: Feb 2002 Location: Phoenix AZ	I forgot to mention the fact that the tweeter wasn't hooked up during the test, I just wanted to see what effects the crossover had on the woofer. Seemed to remove some bass and let alot more treble through. Madmike2 obviously you've never used x-over 2.0 ... I just put in "generic woofer and tweeter" for the name, specs are correct, just did that quick for the screenshots.

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