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Old 7th August 2012, 07:23 PM   #21
layhzer is offline layhzer  Canada
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Originally Posted by Patrick Bateman View Post



A Paraline sub seems like an interesting alternative to the multiple sub approach, because it's not too hard to make the mouth six, eight, or even twelve feet long!

There's one catch though - and that's the humongously long wavelengths. For instance, this experiment started when I was trying to make a 40hz Paraline. Due to the radial expansion of the Paraline, a 40hz Paraline subwoofer ends up being over 7' x 3.5'!


If a 40 Hz Paraline sub is ONLY 7' X 3.5' then I should be able to do a 20 Hz sub with 16' X 8', correct? If so, cool.
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Old 7th August 2012, 07:59 PM   #22
DrDyna is online now DrDyna  United States
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Originally Posted by layhzer View Post
If a 40 Hz Paraline sub is ONLY 7' X 3.5' then I should be able to do a 20 Hz sub with 16' X 8', correct? If so, cool.
You had better post a video of that.

lmfao.
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Old 7th August 2012, 08:12 PM   #23
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Quote:
Originally Posted by Patrick Bateman View Post


A Paraline sub seems like an interesting alternative to the multiple sub approach, because it's not too hard to make the mouth six, eight, or even twelve feet long!

There's one catch though - and that's the humongously long wavelengths. For instance, this experiment started when I was trying to make a 40hz Paraline. Due to the radial expansion of the Paraline, a 40hz Paraline subwoofer ends up being over 7' x 3.5'!

So the reason my Paraline has a square mouth instead of a long skinny one is that I was stacking a Paraline on a Paraline. By doing that, you cut the footprint in half.


I was doing the math in my head, and I was off by a factor of two. An 'eye-shaped' Paraline tuned to 40hz measures approximately 14' x 7'. This is because 40hz is 28.125' long, and our horn is tuned to one-quarter wavelength of that (7.03'). So the 'Paraline Pancake' has a radius of 7.03', and once it's folded it ends up being 7.03' wide by 14.16' tall.

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Old 7th August 2012, 08:24 PM   #24
DrDyna is online now DrDyna  United States
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Quote:
Originally Posted by Patrick Bateman View Post
I was doing the math in my head, and I was off by a factor of two. An 'eye-shaped' Paraline tuned to 40hz measures approximately 14' x 7'. This is because 40hz is 28.125' long, and our horn is tuned to one-quarter wavelength of that (7.03'). So the 'Paraline Pancake' has a radius of 7.03', and once it's folded it ends up being 7.03' wide by 14.16' tall.
Which would make the 20 cycle version ...*looks out the window into the back yard* yeah, the addition can go right over here...

As a 200hz -> 15000hz driver, this looks pretty cool though. I'm watching this for more details, I spent quite a bit of time this morning googling designs and I really want to try one. I wonder if any of my spare drivers are suitable for a test.
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Old 7th August 2012, 08:51 PM   #25
layhzer is offline layhzer  Canada
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Originally Posted by Patrick Bateman View Post
I was doing the math in my head, and I was off by a factor of two. An 'eye-shaped' Paraline tuned to 40hz measures approximately 14' x 7'. This is because 40hz is 28.125' long, and our horn is tuned to one-quarter wavelength of that (7.03'). So the 'Paraline Pancake' has a radius of 7.03', and once it's folded it ends up being 7.03' wide by 14.16' tall.

[/font]
Right. I should have known better. Confession time. I have an old school exponential bass horn that projects into the corner of my listening room. It is 22 feet long and is tuned to about 28 Hz. I built it a long time ago, before hornresp and tapped horns, when I knew even less about horns than I do now. The laws of physics haven't changed in the intervening time.
Sigh.
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Old 7th August 2012, 09:40 PM   #26
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Which would make the 20 cycle version ...*looks out the window into the back yard* yeah, the addition can go right over here...

As a 200hz -> 15000hz driver, this looks pretty cool though. I'm watching this for more details, I spent quite a bit of time this morning googling designs and I really want to try one. I wonder if any of my spare drivers are suitable for a test.
But the cool thing is that it's still skinny!

Click the image to open in full size.

For instance, let's say you want to make a Paraline out of a sheet of 4'x8' lumber. To make it 'disappear', you turn it into a room divider. A room divider is ideal, because it gives us an opportunity to put the loudspeaker in the center of the room, away from boundaries, where loudspeakers sound best.

Now you might think that if you went with a 4'x8' Paraline that it would have to be a couple of feet thick, but it doesn't. In fact, it's better if it's skinny because skinny plays higher in frequency.

And a 4'x8' foot Paraline goes pretty deep - all the way down to 70hz. That's plenty low to mate up with some subs.

If you want to go 'Full Monty' just subdivide the whole room. A Paraline thats 8' tall by 16' wide will play down to 35hz. Now 35hz doesn't sound too low, but this IS a horn after all, so we're going to get all the efficiency and dynamics that come with that... In a package that's 1.25" deep

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Old 7th August 2012, 09:59 PM   #27
DrDyna is online now DrDyna  United States
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....but this IS a horn after all, so we're going to get all the efficiency and dynamics that come with that... In a package that's 1.25" deep
This is exactly why I'm itching to try one of these. I've had my hands dirty with box speakers for a number of years...I'm looking for some new stuff to eff with. What's in your video looks just elegant enough to be the ticket. I even went and looked at BMS compression drivers this morning to see how much this would cost me if I went full monte on it.
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Old 7th August 2012, 10:39 PM   #28
badman is offline badman  United States
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Interesting design- certainly has lots of applications, though my concern would be with the huge internal reflection mechanism, a very narrow radius 180 degree bend, and then another rapid bend/termination at the end.

But still very cool!
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Old 8th August 2012, 12:17 AM   #29
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Interesting design- certainly has lots of applications, though my concern would be with the huge internal reflection mechanism, a very narrow radius 180 degree bend, and then another rapid bend/termination at the end.

But still very cool!
Reflections, high order modes, diffraction, and all that terrible stuff can't occur when the size of the wave is much much bigger than the duct that it's moving through. For example, you can't make a tidal wave in a swimming pool - the pool is simply too small to contain it.

That's why the height of the horn is just 1/4". That height means that any wavelength below 18,000hz simply can't form in the device. (The wave forms at the mouth.)

The formula is (wavelength / duct height / 3 ) or (34,000cm per second / 0.635cm / 3)
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Old 8th August 2012, 01:44 AM   #30
badman is offline badman  United States
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They can't form as standing waves or reflections between the parallel surfaces in any meaningful fasion, no. My concern is with the larger dimension- 4-5" long or more, in which a wave can encounter the obstacle that is the 18 degree turn.

We're talking 3d- any one dimension can create a problem in this respect. Normal considerations are for straight or VERY mildly curved ducts.
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