Square Pegs - Page 58 - 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 5th November 2013, 06:32 PM   #571
gedlee is offline gedlee  United States
diyAudio Member
 
gedlee's Avatar
 
Join Date: Dec 2004
Location: Novi, Michigan
Quote:
Originally Posted by Patrick Bateman View Post
If in doubt, read the patent
Short of reading the patent, the "instantaneous flare rate" would be the slope of the bounding curve? Or the second derivative? It has to be one or the other because higher order derivatives are not guaranteed to exist or be finite.

Stated in these terms, an OS waveguide has the lowest 2nd derivative given an initial slope of zero and a final slope of whatever the design angle is. Since the internal diffraction is proportional to the 2nd derivative, the OS has the lowest internal diffraction for the two given slope conditions.
  Reply With Quote
Old 6th November 2013, 10:48 AM   #572
JLH is offline JLH  United States
diyAudio Member
 
JLH's Avatar
 
Join Date: Apr 2005
Location: Indianapolis, IN
Quote:
Originally Posted by mefistofelez View Post
Hi JLH,

thank you for the response. My English must be really poor, since it appears that I could not get my question across.

I do understand how you and Patrick Bateman are using Hornresponse to calculate the "local area of expansion (the local flare rate)" as you describe it.

However, I was trying to understand the concept of local flare rate a the application thereof to the driver loading. I have derived a relationship based on my assumption of what the Synergy patent is trying to disclose, but the resulting curves when overlaid on Patrick Bateman's curves, purportedly derived by your method from Hornresponse, did not agree. Hence my question regarding the underlying concept, to enable me to check my work.

However, yesterday I discovered Tom Danley's "A White Paper on Danley Sound Labs Tapped Horn and Synergy Horn Technologies", wherein Fig. 4 illustrates "Approximate driver loading of SH-50 based on where along the horn the driver is located". When I entered the parameters of SH-50, a square conical horn with 50 deg included angle, to my formula, and overlaid the resulting curve on Fig. 4, I have a match.

Based on the foregoing, I will now proceed under the false assumption that my understanding is correct. ;-)

Kindest regards,

M
Yes, the white paper does a good job of explaining how the conical horn has a variable flare rate as you move down the horn. The conical horn is not a fixed flare rate horn like the exponential, hyperbolic, tractrix, or LeCleach.
__________________
Ah, how beautifully the orchestra sounds before a rain! In a dry sunny day there is no way for the instruments to sound this way!
  Reply With Quote
Old 22nd November 2013, 12:07 AM   #573
diyAudio Member
 
Join Date: Nov 2007
Location: Dallas
Really hard to phase plug a single driver to a line.
Paraline seems one of the few reasonable ways
to avoid crazy path contortions.

But when we synergy 2 drivers to appear from a
point source rather than a line, now each phase
plug delay is self asymmetrical. Maybe this allows
other (not flat) phase plug shapes to be carved?
I'm just saying it might be worth noodling.

Like maybe a slot over a 3inch speaker with a
triangular plate between, making a greater
delay at one end. To synergy in pairs of single
apparent source. Or maybe you guys could
storm up something a little more coherant?

We are also smearing the reflection of the slot
back to the driver, which might be a good thing.
Not all paths of one length to sudden expansion.
But curved delay for a curved wavefront.

Last edited by kenpeter; 22nd November 2013 at 12:21 AM.
  Reply With Quote
Old 22nd November 2013, 12:21 AM   #574
diyAudio Member
 
Patrick Bateman's Avatar
 
Join Date: Oct 2006
Location: San Diego
Quote:
Originally Posted by kenpeter View Post
Really hard to phase plug a single driver to a line.
Paraline seems one of the few reasonable ways
to avoid crazy path contortions.

But when we synergy 2 drivers to appear from a
point source rather than a line, now each phase
plug delay is self asymmetrical. Maybe this allows
other (not flat) phase plug shapes to be carved.
I'm just saying it might be worth noodling.

Like maybe a slot over a 3inch speaker with a
triangular plate between, making a greater
delay at the ends. Or maybe you guys could
storm up something a little more coherant?
When I put a BG NEO 8 in a Paraline I noticed something odd -
The polar response *in* the Paraline was better than the polar response 'naked'.

I *did* lose some efficiency, but if good polars are a goal, there's some interesting possibilities.

Another thought I had was to do the Paraline in reverse:
A Paraline takes a circular wavefront, a compression driver, and it makes it ribbon shaped.
But there's nothing to stop you from going the other way:
Take a ribbon shaped diaphragm, and make it a circle.

Click the image to open in full size.
^^ picture this with a ribbon at the exit instead of the entrance

This could allow some very interesting loudspeakers, such as a big Raven ribbon loading a circular waveguide.

The BG drivers are almost ideal though, because there's no cavity underneath the diaphragm, like there is in a ribbon.
  Reply With Quote
Old 22nd November 2013, 12:54 AM   #575
diyAudio Member
 
Join Date: May 2003
Location: Washington State, USA
Patrick, do you get the impression that a Paraline produces something strongly resembling a cylindrical wavefront? Does SPL drop off smoothly as one listens off-axis toward the top or bottom of the slot (allowing of course for some diffraction effects due to the slot needing to terminate in some manner) or is there the more usual interference and comb filtering that messes up the high end first? Does the wavefront emitting from a Paraline "want" to travel straight like a laser beam, from a perspective of vertical directivity? Or is it more like an infinite number of point sources that spray in all directions, with the vertical directivity arising from self-interference and lobing?

I do realize I'm asking a possibly complex question about sound propagation in not-very-precise language and sort of hoping your listening or your understanding of the theory hints at an answer. I'd appreciate any thoughts.
  Reply With Quote
Old 22nd November 2013, 08:08 PM   #576
diyAudio Member
 
Join Date: Jan 2008
Quote:
Originally Posted by HeatMiser View Post
1)Patrick, do you get the impression that a Paraline produces something strongly resembling a cylindrical wavefront?
2) Does SPL drop off smoothly as one listens off-axis toward the top or bottom of the slot (allowing of course for some diffraction effects due to the slot needing to terminate in some manner) or is there the more usual interference and comb filtering that messes up the high end first?
3)Does the wavefront emitting from a Paraline "want" to travel straight like a laser beam, from a perspective of vertical directivity? Or is it more like an infinite number of point sources that spray in all directions, with the vertical directivity arising from self-interference and lobing?
1) Not Patrick, but I have done a lot of Paraline measurements.
The wavefront at high frequencies resembles a portion of a cylinder.

2) A non divergent (equal path length from driver to exit center, top and bottom) Paraline has virtually no vertical beamwidth at VHF.
The actual vertical dispersion for a single 20 centimeter tall Paraline would be roughly 5 degrees at 16 kHz going to near 180 degrees below 1000 Hz.

3) The vertical directivity is a result of the Paraline equal path length resulting in a planar wavefront which diffracts horizontally, the horizontal dispersion controlled by the waveguide angle.
  Reply With Quote
Old 22nd November 2013, 08:18 PM   #577
diyAudio Member
 
Join Date: Jan 2008
Quote:
Originally Posted by Patrick Bateman View Post
When I put a BG NEO 8 in a Paraline I noticed something odd -
The polar response *in* the Paraline was better than the polar response 'naked'.

I *did* lose some efficiency, but if good polars are a goal, there's some interesting possibilities.

Another thought I had was to do the Paraline in reverse:
A Paraline takes a circular wavefront, a compression driver, and it makes it ribbon shaped.
But there's nothing to stop you from going the other way:
Take a ribbon shaped diaphragm, and make it a circle.
This could allow some very interesting loudspeakers, such as a big Raven ribbon loading a circular waveguide.
Patrick,

Other than being "interesting", what possible reason would you have to take a ribbon (which the Paraline emulates in polar response) and then convert it (with attendant losses and frequency response peaks and dips) to the radiation pattern of a compression driver that would do a far better job at driving a circular waveguide?

Your idea of "better polar response" is often at odds with what I find to be better, could you show the BG NEO 8 raw polar response compared to the Paraline?

Art
  Reply With Quote
Old 22nd November 2013, 08:34 PM   #578
diyAudio Member
 
Patrick Bateman's Avatar
 
Join Date: Oct 2006
Location: San Diego
[QUOTE=weltersys;3713174]Patrick,

Other than being "interesting", what possible reason would you have to take a ribbon (which the Paraline emulates in polar response) and then convert it (with attendant losses and frequency response peaks and dips) to the radiation pattern of a compression driver that would do a far better job at driving a circular waveguide?[/img]

1) no one has done it
2) NEO8s and NEO3s sound great
3) The most compelling reason is space. I do a lot of car projects and there's a lot of situations where the sheer size of the driver becomes a problem. That was the thing that got me hooked on Paralines was the ability to turn sound 180 degrees or 360 degrees.

For the Synergy horns I'm building now I'm not using Paralines because I think that the Paraline is only useful in certain 'edge' cases.


Quote:
Originally Posted by weltersys View Post
Your idea of "better polar response" is often at odds with what I find to be better, could you show the BG NEO 8 raw polar response compared to the Paraline?

Art
Click the image to open in full size.

Here's the response of my NEO8s "bare". This is a special NEO8, only sold by GR Research, which is why the response looks different than what you see from PE.

On axis is yellow.
45 degrees off axis horizontally is red.
45 degrees off axis vertically is orange.

Note that the off axis drops like a rock, as illustrated by the orange line. This could be good or bad depending on your application, but it's clearly wildly asymmetric.

Click the image to open in full size.
Here's the same driver, in a Paraline. On axis is yellow, 45 degrees off axis horizontally is red, 45 degrees off axis is orange, and the 'naked' response is grey. Note that the on-axis and the 45 degree off axis response 'tracks' each other closely. It's true that the Paraline is wiping out a lot of output above 5khz. At 10khz, the Paraline is down by 20 decibels.



One thing that kinda sucks about my measurements is that the Paraline "sounds" louder but the measurements show that the "raw" NEO8 is louder. I'm not sure what the story is there, it's possible that I may have adjusted the levels at one point. It doesn't make sense to me why the Paraline shows lower in the SPL output compared to the raw NEO8.
  Reply With Quote
Old 22nd November 2013, 09:41 PM   #579
diyAudio Member
 
Join Date: Jan 2008
Quote:
Originally Posted by Patrick Bateman View Post
One thing that kinda sucks about my measurements is that the Paraline "sounds" louder but the measurements show that the "raw" NEO8 is louder. I'm not sure what the story is there, it's possible that I may have adjusted the levels at one point. It doesn't make sense to me why the Paraline shows lower in the SPL output compared to the raw NEO8.
Makes sense to me, you ruined the forward response by putting the Paraline in front of a dipole ribbon (about the same thing as putting a folded towel in front of it), which makes the rear louder.

The response of that driver looks Monster Massive terrible .
  Reply With Quote
Old 22nd November 2013, 09:42 PM   #580
diyAudio Member
 
Patrick Bateman's Avatar
 
Join Date: Oct 2006
Location: San Diego
Quote:
Originally Posted by weltersys View Post
Makes sense to me, you ruined the forward response by putting the Paraline in front of a dipole ribbon (about the same thing as putting a folded towel in front of it), which makes the rear louder.

The response of that driver looks Monster Massive terrible .
the rear was sealed off. So Paraline in the front, sealed in the back.
  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 12:28 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