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Multi-Way Conventional loudspeakers with crossovers

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Old 21st September 2009, 08:45 PM   #6101
mige0 is offline mige0  Austria
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Originally Posted by gedlee View Post
Erling

Whether it is or isn't is not the point. Most of us in this discussion have designs which are "the best in the world" - it's strange how many of those there are!
Actually don't think so - there is imense support for others around here - it's just that usually one can speak from his own limited experience only - most are even aware of this limitation as well...


Michael

Last edited by mige0; 21st September 2009 at 08:48 PM.
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Old 21st September 2009, 10:53 PM   #6102
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Originally Posted by KSTR View Post
OTOH if the slopes are not very steep the intrinsic ringing of the indivudual ways would likely not be much of a problem, while with, say, a LR8 response the off-axis summation would be noticably compromised by the ringing, right?

- Klaus
I agree. But it is an interesting delema. I'll discuss more later.
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Old 21st September 2009, 11:27 PM   #6103
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Originally Posted by skorpion View Post
For the moment I am listening to an oversimplified Emerald Physics clone consisting of two Eminence Alphas and a Vifa D27TG35-06 tweaked by cutting its back chamber off mounted in this same MJAO baffle. No waveguide but playing through SRC2496 and DCX2496 EQ this speaker presents itself with an authoritative statement I didn't think possible. So what shouldn't happen with the PE waveguide and proper positioning for time alignment: http://www.audiocircle.com/index.php?topic=53821.120 .

/Erling
Erling,

why would you go (seemingly) backwards from your Mjao (with a dedicated midrange) to CS2 clone (crossing 15" Eminence to a dome tweeter is bound to have problems, power handling, polar response, radiated power, acoustic signature/distortion characteristics around crossover, you name it) ? Apart from a pure academic exercise ? After all, even Emerald Physics themselves abandoned the concept.

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Old 22nd September 2009, 01:56 AM   #6104
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Originally Posted by john k... View Post
Additionally, a 3rd order, quasi Linkwitz type crossover is easily constructed by cascading a B2 with a B1 filter and delaying the high pass section by 0.25 wave lengths at the crossover frequency. The response error will be +0, -1.2dB max. This is easily constructed using passive elements.

For the HP,

C1 = 1/(4 Pi R F), C2 = 1.2 /(Pi R F), L = 1/(2.4 Pi R F)

For the LP

L1 = R/(Pi F), L2 = R/(4.8 Pi F), C = 0.6 /(Pi R F)

Offset tweeter by 0.25 wave lengths at the x-o frequency and connect with inverted phase. I don't know if this is in your "4" or not.
So this quasi LR3 would have a driver overlap halfway between LR2 and LR4? With nearly symmetric lobing? When you offset the tweeter you are referring to its AC versus the woofer AC? So the tweeter would truly be behind the woofer in a real speaker? If we left the polarity normal is there some place farther ahead we could place tweeter and still keep its impulse in relatively the same time as the woofer, or does the polarity flip delay it 180 degrees with the offset causing another 90 degrees, making the whole thing work?
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Old 22nd September 2009, 01:58 AM   #6105
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Originally Posted by gedlee View Post
I had not gone out of my way to design phase nuetral crossovers as I am not a big believer in phase audibility, but then as I worked through the crossover to yield the best polar response, i.e. both on and off axis, I found that this did in fact yield the lowest group delay in the impulse response and hence the most linear phase system response. If this is coincidence or not I don't know, but it only makes sense that a minimizing the phase difference between two drivers at the crossover - from whatever causes - will yield the best polar response.
Asking again in case you missed my question Earl: can I take this to mean you have decided to use the LR family of filters?
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Old 22nd September 2009, 02:12 AM   #6106
gedlee is offline gedlee  United States
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Originally Posted by augerpro View Post
Asking again in case you missed my question Earl: can I take this to mean you have decided to use the LR family of filters?
Brandon

Yes, I did miss this.

As I have said over and over again I don't obsess over filter names. I do what works acoustically given the wildly variant amplitude and phase of a CD waveguide near cutoff. Electrically the filters are a mess not resembling anything that I have ever seen. Acoustically the summed impulse response is extremely compact with basically only the ringing of the woofers HP. I like to called them Semi-quasi-odd-order-Einsteinium-linear-phase-Gaussian - but that's why I stay away from the "name" thing.
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Old 22nd September 2009, 02:18 AM   #6107
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I guess what I'm getting at is the acoustic phase of the drivers basically in phase (LR type) or in phase quadrature (BW type), or some middle ground? (on axis) Even if a middle ground it must tend toward one ideal or another.
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Old 22nd September 2009, 03:00 AM   #6108
gedlee is offline gedlee  United States
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Originally Posted by augerpro View Post
I guess what I'm getting at is the acoustic phase of the drivers basically in phase (LR type) or in phase quadrature (BW type), or some middle ground? (on axis) Even if a middle ground it must tend toward one ideal or another.
Driver are either in-phase or out-of-phase, there is no middle ground - "phase quadrature" is not a possibility. On some of my systems the drivers are in-phase and on others out-of-phase. As soon as you talk about "on-axis", then you have to specify a field point and things like displacement of the drivers, etc. come in to play. My point is simply that simplifying the problem down to "named" filters with defined relationships like phase (and some peoples absolute ban on "out-of-phase" drivers) is totally missing the point. Waveguides put the source well back of the baffle, and they have significant frequency dependent delays, while the woofer is general on the baffle - is this not all part of the phase problem? My eyes just gloss over with all this talk of phase linearity, and "Quasi" this and that. It might make sense, but its all irrelavent to me.
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Old 22nd September 2009, 03:31 AM   #6109
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Earl, I think Brandon (and most of the rest of us with a clue) understands that 'named' crossover types apply to the acoustical response not the electrical transfer function. Anyone with any modern software (LspCAD, SoundEasy, Passive Crossover Designer, Speaker Workshop, etc.) is using real measured magnitude and phase response of the drivers on the baffles and optimizing electrical components to give the desired acoustical magnitude and phase.

Rather than assuming we're all stupid and that we're referring to electrical transfer functions, please do us the courtesy of assuming we know what's going on because we do.
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Old 22nd September 2009, 03:44 AM   #6110
soongsc is offline soongsc  Taiwan
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Originally Posted by gedlee View Post
Brandon

Yes, I did miss this.

As I have said over and over again I don't obsess over filter names. I do what works acoustically given the wildly variant amplitude and phase of a CD waveguide near cutoff. Electrically the filters are a mess not resembling anything that I have ever seen. Acoustically the summed impulse response is extremely compact with basically only the ringing of the woofers HP. I like to called them Semi-quasi-odd-order-Einsteinium-linear-phase-Gaussian - but that's why I stay away from the "name" thing.
That's really a mouthfull. I have the same situation here. For some reason I just don't go by the standard format either.
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