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Multi-Way Conventional loudspeakers with crossovers

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Old 11th April 2013, 12:30 AM   #31
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I lined the inside of my Paralines (as well as the mid ports/frustums) with open cell foam too. Cleaned up the response a bit over 8khz and definitely sounds much smoother.

I agree that the Paraline mouth is difficult. I remade my mouth exit reflectors but my horn shells could use a lot of work in the transition. Even if the waveform is passing through the Paraline without diffraction/HOM the quick angle change/expansion at the mouth transition has to be a source of diffraction even with a nice gradual transition to a conical horn. I'd also say that the CD entrance is difficult to get right.....mine need work there as well
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Old 11th April 2013, 04:31 PM   #32
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Quote:
Originally Posted by bwaslo View Post
Patrick,

Go with a 90deg width, that makes the guide shorter.

The directiviy lower frequency is set by the mouth size after the second expansion flare, which widens to avoid waistbanding per Keele's prescription....it also makes the horn shorter for the same final mouth size. So the horn mouth is bigger than your 15cm. You could make the available 50cm be the outer edge of the waistbanding flare.
Good advice, and with a 90 degree horn corner mounted, the walls make the mouth area huge in the horizontal.
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Old 19th April 2013, 10:45 PM   #33
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Here's the current status on this project:

1) On the first page of the thread, I detailed a few options to build some speakers. It basically boiled down to either building an existing Unity or Synergy horn design, or striking out on my own. If I went out on my own, I was going to go with a Kef UNI-Q in a Synergy horn, or a pair of Dayton D250Ps in a Paraline box similar to the VTC Paraline boxes.

After spending a couple weeks weighing the options, I was leaning towards the second option. But research indicated that some of the reasons that I like the Paraline are a function of the horn geometry, nothing intrinsic to the Paraline itself. Basically, a narrow angle horn raises the output level of the compression driver in the midrange. And not by a little, by a LOT.

Click the image to open in full size.
On a Paraline my little CDX1-1425s probably "see" about 5-10dB of gain at 1khz. That's one of the reasons the Paralines have worked so well for me. The CDX1 is struggling to get to 1khz, and the narrow coverage of the Paraline brings up the output right where I need it, at the xover point to the midranges.


The problem with the Paraline - which I'd never even considered - is PATTERN FLIP.

Click the image to open in full size.
Basically the horizontal coverage on the Paraline boxes is consistent, because of the 90 degree walls. But the vertical coverage sloooowly narrows as we go higher in frequency. In the octave around 500-1000hz it flips. ('pattern flip')

Having listened to horns in cars for years, I'm very familiar with this distortion, it's nasty. More info and pics here:

Square Pegs

Anyways, what I'm thinking about doing is a horn that's conical on the horizontal axis, and LeCleach on the vertical axis. Basically the vertical coverage won't be as even as the horizontal coverage, but 'pattern flip' will happen verrrrry gradually, which should sound better. Plus, the narrower directivity, compared to a 90x90 conical horn, will increase on-axis SPL at the xover point. That should make it easier to cross over to the mids, plus it just sounds better. (Lowers harmonic distortion.)
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Old 20th April 2013, 12:56 AM   #34
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Click the image to open in full size.

In the last post, I talked about using a LeCleach curve for the vertical axis of the horn, and a conical curve for the horizontal axis of the horn.
I put together a spreadsheet to test my hypothesis, and it's looking quite promising.

The sims above compare all three types - conical, lecleach, and my 'hybrid lecleach'
In the sims we see the following:
1) LeCleach is both the largest and the one with the greatest SPL at the xover point
2) Conical is the smallest, but it also has the lowest SPL at the xover point. Quite a big drop really; about ten decibels lower at 1khz than LeCleach.
3) Conical has the most constant coverage; LeCleach basically goes from 30 degrees of coverage at 14khz, to 90 degrees at 3khz, where the pattern rapidly widens. Conical is basically 90 degrees of coverage down to 1khz (the xover point.)


According to the SPL graphs, they 'hybrid' is somewhere in between. Not as efficient as LeCleach, but not as big either. Hornresp can't do polar plots on multi-stage horns, but I'm willing to bet that the polar plots will be somewhere in between LeCleach and conical.


Seems like a good compromise for a home Synergy horn. Basically use the larger horn size to bump up the output at the xover point, because it's hard to get the mids to play high enough. But it won't beam as much as a 'real' LeCleach horn.

Or at least that's the plan.

It's going to rain all weekend so I think I'll start building a mold tomorrow.

But first, I'm off to see Prince!
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Old 20th April 2013, 03:40 AM   #35
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Signing up for this one!
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Old 20th April 2013, 05:43 AM   #36
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Forgive the foolish question - are you guys talking about which off the shelf flare to use or how to design a flare?
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Old 20th April 2013, 06:54 AM   #37
tinitus is offline tinitus  Europe
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how about making the first part of the horn like a 4 section 'multicell'
maybe it would improve hornloading the side mounted drivers
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File Type: png unity multicell.png (3.2 KB, 192 views)
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