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Old 4th September 2012, 04:36 AM   #151
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Quote:
Originally Posted by AndrewT View Post
David,
my head must have got twisted back to front when I pulled on my pull-over this morning.

Could you explain that for me.
Hi Andrew,

Unless I hear from you to the contrary, I will assume that James' detailed explanation has clarified things for you.

I agree that it can be a little confusing - even the late great Paul Klipsch managed to get it wrong in his classic 1941 paper when he stated that the now-famous bass corner-horn design had an initial "conical" taper. He later corrected this to "parabolic" in his follow-up 1943 paper :-).

Kind regards,

David
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Old 4th September 2012, 10:05 AM   #152
AndrewT is offline AndrewT  Scotland
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That explains a lot.
I had thought from seeing the section shape that the parabolic increased faster than the conical. But that is now obviously back to front thinking.
The conical actually expands faster even though the section shows straight edges.
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Old 5th September 2012, 06:40 AM   #153
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Quote:
Originally Posted by AndrewT View Post
I had thought from seeing the section shape that the parabolic increased faster than the conical.
Hi Andrew,

It does - at least at the throat end :-).

As can be seen from the comparison below, the plane cross-sectional area near the throat of a parabolic horn (red trace) increases at a faster rate than it does for a conical horn (blue trace). The parabolic and conical horns used in the example each have S1 = 100, S2 = 10000 and L12 = 100.

Note that the chart shows horn area, not horn radius.

Kind regards,

David
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File Type: png Area.png (79.6 KB, 528 views)
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Old 5th September 2012, 09:28 AM   #154
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by David McBean View Post
.......... the chart shows horn area, not horn radius..........
Thanks for sticking with me.

I wonder if this is where my confusion comes from? Mistaking radius and area in plots.
The red looks like a cone to me. That suggested conical. But is actually parabolic AREA!

And "par" in the data input is not parallel but parabolic !!!
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Last edited by AndrewT; 5th September 2012 at 09:31 AM.
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Old 5th September 2012, 09:52 AM   #155
Djim is offline Djim  Netherlands
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Old 5th September 2012, 11:09 AM   #156
Thawach is offline Thawach  Thailand
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guy i fell confuse a little when see 2 graphs. the below i ever saw last year ago.
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Old 6th September 2012, 07:30 AM   #157
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Quote:
Originally Posted by AndrewT View Post
The red looks like a cone to me. That suggested conical. But is actually parabolic AREA!

And "par" in the data input is not parallel but parabolic !!!
Hi Andrew,

You are correct, the area expansion rate shown by the red trace is linear or "conical". The corresponding radius expansion however (which defines the horn) is parabolic. A parabolic horn therefore has a linear area expansion. Perhaps it may have been less confusing if I had used the descriptors "Area of Par Horn" and "Area of Con Horn" on my initial comparison chart, rather than "Par Area" and "Con Area".

The attachment below shows the same two horns as before, but this time with the radius plotted, rather the cross-sectional area.

And yes… in Hornresp, Par means a parabolic flare horn :-).

Kind regards,

David
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File Type: png Radius.png (78.0 KB, 475 views)
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Old 10th September 2012, 04:38 PM   #158
DrDyna is offline DrDyna  United States
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So, I did it.

The sims with the TC Sounds Epic 12 and a 5 mh series coil looked pretty good, so I ordered 2 drivers and built two of these over the weekend. 5 sheets of MDF, 2 full tubes of PL Premium and about 2 lbs of 3 inch screws later, here they are. Figured out a fairly decent way of doing the driver access panel, which was to take some of the front panel and glue it to a larger piece that went the whole width, resulting in a cute "cap" that can be unscrewed if the driver needs to come out. Mounted the drivers this morning and somehow managed to dolly 2 of these cabinets made out of MDF down into the media room. Almost no cussing!

I've ordered a MiniDSP to go along with this. I plan to eliminate the coil once it arrives and I can bust out the microphone and dial them in properly, but let me just say, running some medium level tunes through these just to start breaking in the drivers...the output with a pair of these is nothing short of breathtaking (almost literally).

I'm bound to raise a few eyebrows at gatherings and cause a few giggles during movies.

Color me impressed.

Thanks to everyone who had a hand in the cabinet design.

Edit: A pic of my celebration toast. Cheers!
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File Type: jpg 20120910_112446.jpg (121.0 KB, 450 views)
File Type: jpg celebration.jpg (127.0 KB, 438 views)
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Last edited by DrDyna; 10th September 2012 at 04:44 PM.
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Old 12th September 2012, 12:49 AM   #159
tb46 is offline tb46  United States
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Hi DrDyna,

Well done on a quick build. It would be great to learn about your experiences with the MiniDSP in this project.

Regards,
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Old 12th September 2012, 12:53 AM   #160
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I'm using the mini DSP AFTER the receiver sub output, before the amp, to run high and low pass filters on my lab 12 sub.

Only problem I see with that is adding even more delay to the LFE...I have delayed the rest of my speakers as much as possible with the onkyo receiver, but the bass is still lagging slightly. Now for movies (99.9% of what this sub is used for, it's rarely turned on when NOT watching a movie) its fine, powerful and deep. You don't really notice the delay. But with music, you can tell it sounds slightly muddy...

I'm not sure of the exact delay introduced by the mini DSP itself but I know the processing does take time....
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