Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Multi-Way Conventional loudspeakers with crossovers

In Pursuit of a 20-20k Dipole Loudspeaker
In Pursuit of a 20-20k Dipole Loudspeaker
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 12th January 2019, 09:13 AM   #211
ScottG is offline ScottG  United States
diyAudio Member
 
Join Date: Feb 2003
Location: US
Quote:
Originally Posted by Juhazi View Post
Of course in nearfield there won't be any dipole cancellation, you will hear (or measure) better response. And of course there won't be reflections or modes etc. because the direct sound is masking them.

..I have been considering dipole woofer units for many years naturally, at least to find out the difference to monopole unit. I would need a pair of them to find out how stereo works in my room with them..
I've mentioned the "trick" to this before.

Near-field:

1. Stereo dipole,

2. adjust the driver so that the null drops-off significant (3db or more) pressure between one ear and the other. In otherwords get it to where there is cancellation for the listener. (..note that this isn't simply a matter of driver direction because of phase rotation/delay.) Ideally you do it with good measurements, but you can still hear it when it's operating properly.

-again, it's that pressure difference (ILD) at lower freq.s that is utterly uncommon (regardless of room effects). Not unlike head-shading at higher freq.s that naturally produce ILD.


Try it with a range of material. A fair bit just isn't mixed with much difference between L & R.. but when it is - it's quite noticeable. (..no doubt that those using headphones in the production process typically produce material that has more L & R lower freq. differences.)

(..of course when the pressure difference is too great you'll get an in-head effect like what headphones produce (..regardless of the material), but here (near-field dipole setup with cancellation) we aren't talking about much of a pressure difference between the listener's ears and certainly no where near the difference with headphones - even when using open-back headphones.)
__________________
perspective is everything

Last edited by ScottG; 12th January 2019 at 09:22 AM.
  Reply With Quote
Old 12th January 2019, 11:59 AM   #212
bentoronto is offline bentoronto  Canada
diyAudio Member
 
Join Date: Jan 2008
Location: Toronto and Delray Beach, FL
In Pursuit of a 20-20k Dipole Loudspeaker
I would first like to observe that this thread seems to have a lot of speculation and novel theories and very little evidence by way of measurements.

Second, I think some people's subjective judgments of bass goodness are wrong, mistaking pop recordings with lots of boost 60-90 Hz for the real low bass thing. Again, measurements are needed (including real-time analysis of just what bass is on the recordings cited).

Sticking a dipole sub behind your head follows the same principles as sticking any other kind of sub behind your head. And it doesn't change the acoustics of the dipole from a dipole in other locations. For example, it doesn't change the cancellation analysis except that in the absence of reflections, you are missing the phase randomization advantages that you get near a wall. For sure, you do get extreme time-misalignment with the satellites.

But an important advantage of an up-close dipole sub is that you can pump in real big Linkwitz Transform and not over-drive the driver.

Many decades ago, I took a spare 12-inch full-range driver ("Norelco") and hung it naked on a cord from my workshop ceiling near my head. It was wired in series with a large-value toroid coil I found in the Bell Labs stockroom, simple as that. Pretty nice sound, at least while the tools were running in the background.

B.
__________________
HiFi aspirations since 1957. Currently working on motional feedback again... the final frontier in audio (also, see recent post with data on a 17-foot labyrinth sub)

Last edited by bentoronto; 12th January 2019 at 12:01 PM.
  Reply With Quote
Old 12th January 2019, 07:49 PM   #213
pixelpusher is offline pixelpusher  United States
diyAudio Member
 
Join Date: Oct 2004
Location: Minneapolis
Following up on my post #163; Images of the cabinet are posted there.

I have made nearfield measurements from both sides of the cabinet. The two slots on the front were added together. The front and back are pretty similar save for two sharp resonances.
Attached Images
File Type: png Front and back comparison.PNG (63.7 KB, 178 views)
  Reply With Quote
Old 12th January 2019, 08:00 PM   #214
pixelpusher is offline pixelpusher  United States
diyAudio Member
 
Join Date: Oct 2004
Location: Minneapolis
I've done simulations using "Edge". Tried several driver sizes and arrangements. The choice of driver size makes a big difference. I've not found a way to export the response as a text fie from Edge. If anybody knows a way please let me know. The pics attached I think show the closest approximation of this cabinet. Probably an average of these two would be closest to reality.
Attached Images
File Type: png Edge_2_slot.PNG (147.3 KB, 181 views)
File Type: png Edge_1_slot.PNG (148.5 KB, 175 views)
  Reply With Quote
Old 12th January 2019, 08:13 PM   #215
pixelpusher is offline pixelpusher  United States
diyAudio Member
 
Join Date: Oct 2004
Location: Minneapolis
It occurs to me that by adding some insulation or absorptive material at the back one could convert this to a cardioid radiation pattern. What do you think?

Last edited by pixelpusher; 12th January 2019 at 08:17 PM.
  Reply With Quote
Old 12th January 2019, 09:32 PM   #216
zmyrna is online now zmyrna  United Kingdom
diyAudio Member
 
Join Date: Nov 2009
Location: London
here is my all time favorite forum thread

frankensteins monitors - Page 13

the guy is using ripole subs to complement his JBL 4435 cabinets
Attached Images
File Type: gif panoramaGIFweb999.gif (199.0 KB, 149 views)
  Reply With Quote
Old 12th January 2019, 09:42 PM   #217
scottjoplin is offline scottjoplin  Wales
diyAudio Member
 
scottjoplin's Avatar
 
Join Date: Dec 2015
Location: Penrhyndeudraeth
Quote:
Originally Posted by pixelpusher View Post
It occurs to me that by adding some insulation or absorptive material at the back one could convert this to a cardioid radiation pattern. What do you think?
It's a bit trickier than that, the back wave has to be delayed more than absorbed to create a cardioid
__________________
Woofer Assisted Wideband is the New Testament renounce the anachronistic acronym FAST
  Reply With Quote
Old 12th January 2019, 09:50 PM   #218
Pano is offline Pano  United States
diyAudio Moderator
 
Pano's Avatar
 
Join Date: Oct 2004
Location: SW Florida
In Pursuit of a 20-20k Dipole Loudspeaker
Thanks Cowanaudio! Well found.
  Reply With Quote
Old 13th January 2019, 01:29 AM   #219
kazap is offline kazap  Australia
diyAudio Member
 
kazap's Avatar
 
Join Date: Apr 2011
Location: Brisbane
Quote:
Originally Posted by pixelpusher View Post
Following up on my post #163; Images of the cabinet are posted there.

I have made nearfield measurements from both sides of the cabinet. The two slots on the front were added together. The front and back are pretty similar save for two sharp resonances.

Click the image to open in full size.


Thanks for posting your measurements. Real data is gold. It looks very good to me. Is it a "ripole" type dipole sub you made with four 18" drivers?


Im not sure Edge can model such a complex fold. I tied an estimate with four round drivers on an unfolded ripole but even with my inevitable mistakes I think its a waste of time to be honest. I attached the file by adding .txt. To open it chop off the .txt and use Edge. To save an Edge project go to the window with the plot "Edge Response" > File > Save as.


I think Hornresp would be much better for modelling a ripole - can anyone model it and post up the txt file?


In the meantime it really is real world measurements that matter so thanks so thanks to the tip off
in the frankenstein twin ripoles measured at the listening seat:


Click the image to open in full size.
Attached Images
File Type: jpg Pixelpusher Ripole.JPG (511.6 KB, 18 views)
Attached Files
File Type: txt Edge Pixelpusher Ripole unfolded model.edge.txt (1.3 KB, 3 views)
  Reply With Quote
Old 13th January 2019, 08:33 AM   #220
Juhazi is online now Juhazi  Finland
diyAudio Member
 
Juhazi's Avatar
 
Join Date: Mar 2007
Location: Jyväskylä, Finland
Cowanaudio said "Interestingly a dipoles response flattens out as you get closer to the source. Many dipole bass speakers will need no eq to flatten the bottom end. "

This is the very nature of large dipoles. In the post above there is simulation at 4m and measurement indoor at roughly 1m and we have seen many measurements at the mouth. Indoor measurements are very tricky with all the modes seen with long IR gating required to see low frequencies in the first place.

These a basics that one must comprehend to be able to interprete measurements and statements. Many web pages are full of amazing results with dipole or ripole subwoofers, but I very rarely see descripitons how measurements were done, what size the room was etc. essential info.

Here is pixelpusher's simulation at 10 vs. 1m vs. 20cm distance. His first one had 100m distance (300') Edge has anechoic conditions always.
Attached Images
File Type: jpg dipsub var distance edge.jpg (122.9 KB, 35 views)
__________________
Radikal aktivist AINOgradient speaker project

Last edited by Juhazi; 13th January 2019 at 08:35 AM.
  Reply With Quote

Reply


In Pursuit of a 20-20k Dipole LoudspeakerHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Rockin' the KaZba Dipole (K aperture Z-baffle Dipole) xrk971 Full Range 332 24th February 2018 01:30 PM
Dipole Ribbon tweeter isolation from dipole mid-woofer array Bent Planars & Exotics 8 29th March 2015 09:45 AM
Advice Needed On Dipole/Bipole Wal Mounted Surround Loudspeaker philiprst Multi-Way 9 7th October 2008 07:51 PM
The Eternal Pursuit. devzero Introductions 8 15th August 2008 05:13 AM
Speakers, Ebay, And, The Pursuit Of Winning The Auction OMNIFEX Multi-Way 4 14th March 2003 09:37 AM


New To Site? Need Help?

All times are GMT. The time now is 09:22 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki