Square Pegs - Page 4 - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way

Multi-Way Conventional loudspeakers with crossovers

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 8th August 2012, 03:19 AM   #31
diyAudio Member
 
Join Date: Oct 2005
Gentlemen,

Is there somewhere an article with drawings about the principle of this innovative approach. I looked at Patrick's youtube videos and I still don't understand how it works.
  Reply With Quote
Old 8th August 2012, 11:55 AM   #32
smf is offline smf  United Kingdom
diyAudio Member
 
Join Date: Jan 2005
Location: Hong Kong
Talaerts - the clearest drawings are in the patent application and are very helpful in explaining what's going on in principle.

Like Badman, I'm not clear why there aren't reflections at the bend - that distance must be long enough to be a 1/4 wavelength of some frequency in the passband. Maybe there is but it just isn't audible?
  Reply With Quote
Old 8th August 2012, 03:55 PM   #33
badman is offline badman  United States
diyAudio Member
 
badman's Avatar
 
Join Date: Sep 2003
Location: Sunny Tustin, SoCal
Quote:
Originally Posted by smf View Post
Talaerts - the clearest drawings are in the patent application and are very helpful in explaining what's going on in principle.

Like Badman, I'm not clear why there aren't reflections at the bend - that distance must be long enough to be a 1/4 wavelength of some frequency in the passband. Maybe there is but it just isn't audible?
I can see the resonances being spread-spectrum due to the dissimilar pathlengths, but I'd think it'd still impose a rather significant sonic signature- likewise the termination would want a well-made phaseplug and horn assembly to soften the transition.

I have a couple 3d shapes in mind that would mitigate this challenge, but they're 3d and as such would be exceedingly difficult to explain or build.
__________________
I write for www.enjoythemusic.com in the DIY section. You may find yourself getting a preview of a project in-progress. Be warned!
  Reply With Quote
Old 8th August 2012, 04:53 PM   #34
diyAudio Member
 
Patrick Bateman's Avatar
 
Join Date: Oct 2006
Location: San Diego
Quote:
Originally Posted by talaerts View Post
Gentlemen,

Is there somewhere an article with drawings about the principle of this innovative approach. I looked at Patrick's youtube videos and I still don't understand how it works.
Click the image to open in full size.

Here's the picture from Danley's patent.

Here's a quick overview of how it works:

Click the image to open in full size.
In a conventional conical horn, the horn has width and depth. For instance, you might have a ninety degree conical horn with a depth of 7.5" and a width of 15". There are lots of ways to fold a conventional horn. The pic above shows one of them.

In a conventional horn, the apparent location of the sound varies based on frequency. Basically, high frequencies seem to emanate close to the throat, while low frequencies seem to emanate from the mouth. You can get an appreciation for this by putting your head in front of a folded horn. You'll hear high frequencies seem to come from deep inside the horn. The reason that this happens is that low frequencies dwarf the dimensions of the horn. So you get this wonky situation where the apparent location of the sound is variable. The simplest way to fix this situation is to use a horn with a larger coverage angle, a shallow horn, or both. This has been documented by the AES, I can dig up articles if you want. The Paraline folding attacks the problem from the exact opposite direction. Instead of using a wide shallow horn to fix this problem, the Paraline folds it into a shape that's so small, the diffraction and HOMs can't even form inside of the device. In my videos on youtube, you can hear this for yourself. The Paraline plays audibly higher in frequency than a conical horn, and I would argue that this is because there's no cancellation and comb filtering inside of the device.

Click the image to open in full size.
A Paraline is a horn that radiates in 360 degrees. Picture a series of concentric rings, like the illustration that I made above. You can get a good idea of it's performance by modeling it in hornresp. The main difference is that the depth of the horn is equal to the radius of the ring. For instance, a ring with a diameter of 12" will behave like a horn with a depth of 6".

Click the image to open in full size.

To keep size to a minimum, the horn in the Paraline is folded. For instance, sound emanates from the hole in the center, where the driver is located, proceeds along line D1, is folded over, then continues to proceed over line D2.

There is nothing magical about this device; it's a conical horn that's been folded in a very clever way. But since it's a conical horn, it's a very attractive option for a lot of our projects. For instance, the tapped horns that we've been building like crazy are also conical horns. And, yes, you can make a Paraline into a tapped horn. (Instead of mounting the driver from the back, mount it from the front, with the magnet sticking out of the mouth. Voila! Tapped Paraline horn.

[/font]

Last edited by Patrick Bateman; 8th August 2012 at 04:58 PM.
  Reply With Quote
Old 9th August 2012, 01:05 AM   #35
diyAudio Member
 
Top Shelf's Avatar
 
Join Date: Apr 2010
Location: Midland, Ontario
As I understand this device,its just a single fold right?360 degrees. What about taking it farther and using multiple shelves (or layers) to gain length? The mouth of each layer gets appropriately larger? This should work, or no.
__________________
JEREMY M_________________________________
I like it loud, BUT NOT TOO LOUD!.... Hey do you hear that high pitched ringing sound ?
  Reply With Quote
Old 9th August 2012, 01:23 AM   #36
smf is offline smf  United Kingdom
diyAudio Member
 
Join Date: Jan 2005
Location: Hong Kong
Top Shelf - the patent application says mutliple folds are possible.

Patrick - you've obviously read most about this. Is there anywhere where Tom Danley explains about the exit mouth shape? The patent application for the 'eye' paraline is obviously all about creating a line array effect. But the idea of using a radially concentric expansion to reduce horn depth is a separate issue. I'm interested in both, but I can't quite see how to reduce the height of the eye paraline for lower frequencies. I think it has to be 1/2 wavelegth of the lowest frequency you want. Maybe I missed this in the patent description.
  Reply With Quote
Old 9th August 2012, 02:05 AM   #37
diyAudio Member
 
Join Date: May 2009
Location: New Zealand
One thought from looking at the patent pictures and Patrick's proof of concept model:
The layer with the eye shaped slot will likely need to be very stiff, or braced near the middle, to avoid vibration caused by the high pressures from the driver(s). The vibration would cause it to act as a diaphragm and radiate sound directly out of the slot. In the commerical 2-driver Paralines, they appear to have made the plates from aluminium.

Patrick, I see the ends of some pieces of scrap ply visible in the mouth of your proof of concept, are they to brace the "eye shaped slot" layer? If I were going to build such a model out of ply, I'd mount the drivers with long bolts passing through all layers, with spacers over the bolts where they pass through the voids. This would apply bracing at the point(s) of maximum pressure.
  Reply With Quote
Old 9th August 2012, 02:27 AM   #38
diyAudio Member
 
Join Date: May 2009
Location: New Zealand
As described in the patents, the Paraline appears to be a way to generate a plane wavefront for applications requiring a "line source", rather than as an impedance matching device. It's what I would call a waveguide rather than a horn. Then I look at Patrick's Proof Of Concept, and I suspect it works differently. I assume his model has a radially expanding first part fed by the drivers, a circular (rather than eye shaped) slot, and a "circular" (sort of square) exit. I keep visualising it as a diverging conical horn capped with a converging conical horn, but this ignores the "two dimensional" nature.

Looking at the patent, Fig. 14, imagine a second "item 30" connected in place of "item 32".That's what Patrick's model looks like to me. I must be missing something basic. (I know it's not my marbles, every morning I look in my toybox and there they are.)
Help...

Edit:
I wonder... if you built a device like Patrick's, and used multiple HF drivers clustered closely together in the centre, would the output at the exit combine into a virtual point source? Would this be the basis for a "layered combiner"?

Last edited by Don Hills; 9th August 2012 at 02:30 AM.
  Reply With Quote
Old 9th August 2012, 02:34 AM   #39
diyAudio Member
 
Join Date: Oct 2005
Thanks all for the input, thanks to more pictures from the patent application I now finally see how it is folded between sheets.

What I don't really see is how the flat sheets will provide for a correct horn profile. In another forum I found a crosscut picture that shows the principle but without flat sheets, they would need to machined to properly follow a folded horn path:

Click the image to open in full size.

In the patent application the layers look like an eye, I don't quite see why they shouldn't be circular? It must have something to do with the output hole being a slit.

In Patrick's prototype, you end up with a square output hole. Why wouldn't you end up with a circle instead?
  Reply With Quote
Old 9th August 2012, 03:18 AM   #40
diyAudio Member
 
Join Date: May 2003
Location: Washington State, USA
Quote:
Originally Posted by talaerts View Post
In the patent application the layers look like an eye, I don't quite see why they shouldn't be circular? It must have something to do with the output hole being a slit.

Click the image to open in full size.

Yes. The distances A1+A2, B1+B2, C1+C2, D1+D2 are all equal (A2 is not shown because it is zero). So sounds leaving the driver at the same time exit the slit at the same time.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
My Wave Isn't Square. Troncones Tubes / Valves 186 28th August 2014 12:04 PM
EICO 666 meter needle moves too fast/pegs too hard...help? jasonguitar Tubes / Valves 3 15th September 2010 01:58 AM
What gives with this square wave? martyh Tubes / Valves 23 21st January 2010 09:22 PM
Why are almost all sub boxes square elambert Subwoofers 12 28th May 2005 08:49 PM
Square wave Prune Everything Else 11 28th June 2004 06:17 AM


New To Site? Need Help?

All times are GMT. The time now is 08:20 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2