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Multi-Way Conventional loudspeakers with crossovers

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Old 18th August 2012, 11:51 PM   #101
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If you measure from the driver to the nearest part of the mouth, the path length is the same all around the line - all parts of the wavefront from the driver arrive at the mouth at the same time.
I don't see how this can hold true. If the distance from the source is the same length at all points it would seem that the wavefront must be on a curve not a straight vertical line.

And furthermore, if the "no waves form inside" theory actually works this should also be a HOM / diffraction free horn.

I would argue that this is a diffraction lens. The vertical dispersion is controlled by the height being equal to the longest wavelength giving no diffraction. The narrow slit is working just the opposite and the horizontal dispersion is completely realized through a diffraction affect. This is a diffraction lens if I ever saw one.
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Old 19th August 2012, 12:14 AM   #102
JLH is online now JLH  United States
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Well, I've joined the Paraline club. It is using a Selenium D220TI and a pair of Misco RDC3TA 3" mids. I still need to sand and file some rough spots down before doing the final assembly, but the bulk of the work is done. I have the crossover written down on paper, but I know it will need a little tweaking. It wasn't bad at all building the Paraline. This is SO MUCH EASIER than building conical horn shells. Unless something unforeseen screws this up, this is the only way to build Unity/Synergy horn in my opinion.

Click the image to open in full size.
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Old 19th August 2012, 02:09 AM   #103
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Quote:
Originally Posted by Kindhornman View Post
If you measure from the driver to the nearest part of the mouth, the path length is the same all around the line - all parts of the wavefront from the driver arrive at the mouth at the same time.
I don't see how this can hold true. If the distance from the source is the same length at all points it would seem that the wavefront must be on a curve not a straight vertical line. ...
It's easy to prove it is true. Like I said, measure out from the driver to the "eye" shaped slot, then from the slot to the nearest part of the mouth. Repeat this for any direction out from the driver. Patrick posted a video which demonstrated this with a piece of string.

Last edited by Don Hills; 19th August 2012 at 02:19 AM.
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Old 19th August 2012, 02:18 AM   #104
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Originally Posted by JLH View Post
Well, I've joined the Paraline club. ...
I have my doubts about the effectiveness of the mid drivers. The geometry is dubious - there is no clearly defined position of the drivers in the line. It's a bit like making the midrange openings in a Synergy horn into longitudinal slots instead of round holes. Also, did you calculate the line length to be long enough for the lower cutoff frequency of the mids? It only looks big enough for the tweeter.
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Old 19th August 2012, 03:00 AM   #105
JLH is online now JLH  United States
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Quote:
Originally Posted by Don Hills View Post
I have my doubts about the effectiveness of the mid drivers. The geometry is dubious - there is no clearly defined position of the drivers in the line. It's a bit like making the midrange openings in a Synergy horn into longitudinal slots instead of round holes. Also, did you calculate the line length to be long enough for the lower cutoff frequency of the mids? It only looks big enough for the tweeter.
I addressed all the above concerns during the design process. The details how to add mids to the paraline was clearly covered in the patent. Placement of the mids is also much more forgiving due to the longer wavelengths involved. The acoustic path length of the compression driver along with the distance where the mids tap in were accounted for in my paraline. I've been doing this stuff for a while now. This isn't my first build. I just don't understand all the pessimism around the paraline. I remember the hostility the original Unity horn received when it was first released. I had hoped we were past this kind of negative mindset.
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Old 19th August 2012, 06:20 AM   #106
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The patent's midrange arrangement is quite different, with the ports much closer to the apex. (Fig 9). The further out the ports are, the greater the difference will be between the HF and MF dispersion patterns at the crossover point, and there's a body of opinion that says they should be matched if possible. If you don't subscribe to that argument then no problem...
I'm not against the Paraline. Quite the opposite. My concerns are that modifications made without an understanding of the operating principles may result in disappointment through no fault of the Paraline's design principles, as happened with the Unity horn.
That's not a criticism of your skills. I just expressed my opinion.
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Old 19th August 2012, 03:41 PM   #107
JLH is online now JLH  United States
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Quote:
Originally Posted by Don Hills View Post
The patent's midrange arrangement is quite different, with the ports much closer to the apex. (Fig 9). The further out the ports are, the greater the difference will be between the HF and MF dispersion patterns at the crossover point, and there's a body of opinion that says they should be matched if possible. If you don't subscribe to that argument then no problem...
I'm not against the Paraline. Quite the opposite. My concerns are that modifications made without an understanding of the operating principles may result in disappointment through no fault of the Paraline's design principles, as happened with the Unity horn.
That's not a criticism of your skills. I just expressed my opinion.
Fair enough. How much weight do we give to the dispersion pattern at the crossover point? Looking at the current speaker offerings using the paraline, the mids are not even mounted to the paraline; they're on the horn shell. Having the mids closer to the compression driver and mounting them on the paraline would further minimize this disparity rendering it a moot point. The advantage I see in the paraline is in its radial expansion. This eliminates a lot of problems with midrange placement. If we zoom out and take a more elementary look at the paraline, its just a bifurcated radially expanding horn. If treated as such, and we apply the additional tidbits given in the patent it is a fairly straight forward process.
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Old 19th August 2012, 06:20 PM   #108
winslow is offline winslow  United States
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I have some of the mids...and the neo version of that compression driver.

What kind of bandrange are you going to be running those guys at John? Would adding another mid to make 3 per side do anything significant?

I did love the litte Unities that I came up with.
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Old 19th August 2012, 06:58 PM   #109
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Originally Posted by JLH View Post
Unless something unforeseen screws this up, this is the only way to build Unity/Synergy horn in my opinion.
Looks like a very clean piece of work.
I am very curious as to whether the sharing of a throat may cause intermodulation distortion of the HF driver from the mid drivers.
This is no problem in the Unity/Synergy horn, but your placement is far more "communal".

If you have an RTA, a screenshot of the product of 300 Hz (or whatever the low end of the mid driver is) at a peak operating level and an uneven HF frequency (like 1525 Hz) would be interesting.
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Old 19th August 2012, 07:50 PM   #110
SunRa is offline SunRa  Romania
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Hi,

some questions about the paraline, I can't wrap my head around these matters:

- the diameter of the exit slot still dictates the cut-off frequency, right? In the case of the eye shaped, the cut-off frequency should then be dictated by the length of the slot. That is, if an unfolded horn would have a mouth of 12" then the equivalent paraline would have the same exit slot?

- is the paraline also exhibiting any gain, as a traditional horn?

Thanks!

Quote:
I am very curious as to whether the sharing of a throat may cause intermodulation distortion of the HF driver from the mid drivers.
Not sure if that would be the case, the area were the signals are mixing is still an area of laminar flow. I believe that in some ways it's the same as the compression chambers of the coaxial drivers from BMS.

On the other hand, the distance from the CD exit to the exit slot is optimized while in the case of the midranges is not. And this would mean different wavefronts for the CD and midrange drivers..
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