Beyond the Ariel - Page 638 - 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 27th October 2009, 10:00 AM   #6371
mige0 is offline mige0  Austria
diyAudio Member
 
mige0's Avatar
 
Join Date: Jan 2005
Location: Austria, at a beautiful place right in the heart of the Alps.
Quote:
Originally Posted by john k... View Post
It is an interesting design. Reminiscent of the old Beostatic.

The free field measurement show concern with such large format dipole woofers. Look at the measurement at 1, 3 and 5 in the pdf. You see that the form of the gradient roll off of the dipole is a function of distance from the dipole and the dipole separation.
I am thinking about an arrangement of woofer dipoles - one stacked behind the other - for some time now but can't wrap my head around it how summation or directivity (including the listening distance impact) would be affected.

Might be I'm wrong but it seems to me that when doing so with two 15" at a distance of say 30" there is a sonic pattern in the lower department that "feels" good.

I haven't tried to apply appropriate delay yet to make them "time aligned" for the listening position - just run some simus but failed to draw any meaningful conclusions.

Michael
  Reply With Quote
Old 27th October 2009, 11:29 AM   #6372
diyAudio Member
 
john k...'s Avatar
 
Join Date: Aug 2004
Location: US
Quote:
Originally Posted by mige0 View Post
I am thinking about an arrangement of woofer dipoles - one stacked behind the other - for some time now but can't wrap my head around it how summation or directivity (including the listening distance impact) would be affected.

Might be I'm wrong but it seems to me that when doing so with two 15" at a distance of say 30" there is a sonic pattern in the lower department that "feels" good.

I haven't tried to apply appropriate delay yet to make them "time aligned" for the listening position - just run some simus but failed to draw any meaningful conclusions.

Michael

In the free field, if the axial arrangement is +, -, +, -, you basically still have a dipole at low frequency. As the frequency rises you will have the peaks and nulls but the axial spacing and magnitude will be dependent on the both the dipole separation and the separation between the two dipoles. Pretty much a 6dB increase in low frequency output, but the first null will be below the null for a single dipole. Behavior with distance is qualitatively the same as a dipole at low frequency as well.

Behavior in a room is actually determined by 4 monopole sources with different polarity and positioning, as well as source and baffle size.
__________________
John k.... Music and Design NaO Dipole Loudspeakers.
  Reply With Quote
Old 27th October 2009, 11:53 AM   #6373
Bill F. is offline Bill F.  United States
diyAudio Member
 
Bill F.'s Avatar
 
Join Date: Nov 2001
Location: SW MI
Quote:
I am thinking about an arrangement of woofer dipoles - one stacked behind the other
If the rear dipole element is reverse polarity and delayed by the separation distance divided by the speed of sound, you have a second-order gradient. Basically a hypercardioid loudspeaker with 12dB/oct. acoustic cancellation below Fpeak.
  Reply With Quote
Old 27th October 2009, 07:03 PM   #6374
mige0 is offline mige0  Austria
diyAudio Member
 
mige0's Avatar
 
Join Date: Jan 2005
Location: Austria, at a beautiful place right in the heart of the Alps.
Thanks for your reply, John and Bill.
Interesting to hear that both +/- +/- and +/- -/+ polarity makes sense to you

On the other hand there must be something I didn't get right in my simu's

For the +/- +/- connection I get basically a dipole behaviour slightly asymmetrically changing with frequency but not much.

The +/- -/+ connection is quite a different animal.
Below a stacked dipole at a distance or roughly 3 feet 90cm connected in +/- -/+ polarity at 50Hz to 200Hz with a delay set to meet time of flight

Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.

seems to sum up as a "kind of" cardioid ??

Michael

Last edited by mige0; 27th October 2009 at 07:06 PM.
  Reply With Quote
Old 27th October 2009, 07:19 PM   #6375
Bill F. is offline Bill F.  United States
diyAudio Member
 
Bill F.'s Avatar
 
Join Date: Nov 2001
Location: SW MI
Looks about right to me. The 12dB/octave cancellation is somewhat of a deal-breaker for low bass, though. On the upper end, reflections between the two diaphragms are a limiting factor.

Forum member Hancock used to use this alignment for midbass, IIRC.
  Reply With Quote
Old 27th October 2009, 08:46 PM   #6376
diyAudio Member
 
john k...'s Avatar
 
Join Date: Aug 2004
Location: US
Quote:
Originally Posted by Bill F. View Post
Looks about right to me. The 12dB/octave cancellation is somewhat of a deal-breaker for low bass, though. On the upper end, reflections between the two diaphragms are a limiting factor.
The 2nd order gradient setup is classic, right out of Olson's paper on gradient loudspeakers. I can be thought of as 2 cardioid systems connected out of phase.

Click the image to open in full size.
__________________
John k.... Music and Design NaO Dipole Loudspeakers.
  Reply With Quote
Old 27th October 2009, 09:09 PM   #6377
mige0 is offline mige0  Austria
diyAudio Member
 
mige0's Avatar
 
Join Date: Jan 2005
Location: Austria, at a beautiful place right in the heart of the Alps.
Thats the thread ?

Second Order Gradients


Good read.
The description of the sonic outcome is probably what I got the good feeling from - very exciting !

I was checking - had my 15" dipoles operating out of phase - but at same level (split power by shunt C) and no "RC filter" for the back radiating wave of course...


Room for improvement, as it seems - to do a 2OG setup correctly...

Michael

Last edited by mige0; 27th October 2009 at 09:23 PM.
  Reply With Quote
Old 27th October 2009, 10:03 PM   #6378
mige0 is offline mige0  Austria
diyAudio Member
 
mige0's Avatar
 
Join Date: Jan 2005
Location: Austria, at a beautiful place right in the heart of the Alps.
On the other hand - there seems to be no big benefit compared to a pure cardioid woofer telling from the directivity pattern ?
The lack of needing any dampening material - which is something serious *for me* - is on the pro side though

I remember some have been guessing about what the CS1 double double bass is good for:

Emerald_Physics_CS1

seems to be probably a 2nd order gradient design ?

Michael

Last edited by mige0; 27th October 2009 at 10:07 PM.
  Reply With Quote
Old 27th October 2009, 11:03 PM   #6379
diyAudio Member
 
john k...'s Avatar
 
Join Date: Aug 2004
Location: US
Quote:
Originally Posted by mige0 View Post
Thats the thread ?

Second Order Gradients


Good read.
The description of the sonic outcome is probably what I got the good feeling from - very exciting !

I was checking - had my 15" dipoles operating out of phase - but at same level (split power by shunt C) and no "RC filter" for the back radiating wave of course...


Room for improvement, as it seems - to do a 2OG setup correctly...

Michael
I didn't read that thread but the thing is, when it comes to room response in the modal region it is not about directionality. It is about how the sources couple to the room. Ultimately, be they dipoles, monopoles or cardioids, they are all equivalent to multiple monopole sources distributed around the room, in or out of phase, with or without delay.
__________________
John k.... Music and Design NaO Dipole Loudspeakers.
  Reply With Quote
Old 27th October 2009, 11:08 PM   #6380
diyAudio Member
 
john k...'s Avatar
 
Join Date: Aug 2004
Location: US
Quote:
Originally Posted by mige0 View Post
On the other hand - there seems to be no big benefit compared to a pure cardioid woofer telling from the directivity pattern ?
The lack of needing any dampening material - which is something serious *for me* - is on the pro side though

I remember some have been guessing about what the CS1 double double bass is good for:

Emerald_Physics_CS1

seems to be probably a 2nd order gradient design ?

Michael
More likely the front and rear are both dipole sin phase, used to increase SPL in a somewhat compact package.

Remember that when you get to a 2nd order gradient system excursion goes like (1/f)^4. So over 1 octave excursion goes up by a factor of 16.
__________________
John k.... Music and Design NaO Dipole Loudspeakers.
  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



New To Site? Need Help?

All times are GMT. The time now is 09:28 AM.


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