The Advantages of Floor Coupled Up-Firing Speakers - Page 205 - 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 11th March 2013, 08:33 PM   #2041
Banned
 
Join Date: May 2008
Location: Switzerland
Ceiling and floor reflections are on the cone of confusion and therefore might only affect timbre at lower frequencies.
  Reply With Quote
Old 11th March 2013, 09:02 PM   #2042
graaf is offline graaf  Poland
diyAudio Member
 
graaf's Avatar
 
Join Date: Jun 2007
Quote:
Originally Posted by ScottG View Post
-just ask yourself if there is a change in direction at that freq..

That change in direction is the key component of a reflection.

With Elias's example the floor doesn't cause a change in direction at 400 Hz.
Again - can You please post any reference for this?
I mean an explanation when a reflection can be treated as a specular reflection having regard to the wavelength and to the distance to the reflecting surface? Please be so kind. I would be very grateful.
__________________
"high phooey and hystereo" - Yascha Heifetz
  Reply With Quote
Old 11th March 2013, 09:28 PM   #2043
diyAudio Member
 
Join Date: Jun 2007
Quote:
Originally Posted by WithTarragon View Post
Cone of confusion refers to the binaural differences. Those will be preserved.
Regarding the issue of similar binaural values for the ceiling and floor reflections: I may might need to disagree with myself. I am still thinking this one through
  Reply With Quote
Old 11th March 2013, 09:53 PM   #2044
Elias is offline Elias  Finland
diyAudio Member
 
Elias's Avatar
 
Join Date: May 2003
Location: Where you live
I'm in the design phase of my new loudspeakers, and exploring the floor reflection contribution therein I made some FDTD simulations of the case.

The simulated waveform is a gaussian wavelet like this:
Click the image to open in full size.

The simulation includes reflective floor and ceiling. Vertical ends are absorptive. x and y grids are in meters.

Here is 0.8m tall dipole baffle with 12" element at 20cm above floor (to the center) at 500Hz: There got some edge diffraction from the baffle but no distinctive floor reflection.

Click the image to open in full size.


For reference here the baffle is elevated 1m above floor and element in the center of the baffle at 500Hz: Here a clear floor reflection is seen.
Click the image to open in full size.


- Elias
__________________
Liberate yourself from the illusion of two speaker stereo triangle
Dipole Bass vs Monopole Bass Stereophonic Sound from a Single Loudspeaker 3 Speaker Linear Stereo Matrix Wavelets
  Reply With Quote
Old 11th March 2013, 10:11 PM   #2045
Elias is offline Elias  Finland
diyAudio Member
 
Elias's Avatar
 
Join Date: May 2003
Location: Where you live
Here a snapshot at the time the wave has travelled 3m.

For comparison. 500Hz.

Floor baffle. Nice spherical wavefront. No tail

Click the image to open in full size.


And elevated baffle. Look at that carbage following the direct sound

Click the image to open in full size.


- Elias
__________________
Liberate yourself from the illusion of two speaker stereo triangle
Dipole Bass vs Monopole Bass Stereophonic Sound from a Single Loudspeaker 3 Speaker Linear Stereo Matrix Wavelets
  Reply With Quote
Old 11th March 2013, 10:33 PM   #2046
ScottG is offline ScottG  United States
diyAudio Member
 
Join Date: Feb 2003
Location: US
Quote:
Originally Posted by graaf View Post
Again - can You please post any reference for this?
I mean an explanation when a reflection can be treated as a specular reflection having regard to the wavelength and to the distance to the reflecting surface? Please be so kind. I would be very grateful.
I searched a bit, couldn't find anything that was specifically on-point.

Rather than an affirmation, what's the point of diffraction (which does specifically relate to a wave's length and necessarily distance to an otherwise reflective surface)?
__________________
perspective is everything
  Reply With Quote
Old 11th March 2013, 10:38 PM   #2047
ScottG is offline ScottG  United States
diyAudio Member
 
Join Date: Feb 2003
Location: US
Quote:
Originally Posted by Elias View Post

Here is 0.8m tall dipole baffle with 12" element at 20cm above floor (to the center) at 500Hz: There got some edge diffraction from the baffle but no distinctive floor reflection.

Click the image to open in full size.


For reference here the baffle is elevated 1m above floor and element in the center of the baffle at 500Hz: Here a clear floor reflection is seen.
Click the image to open in full size.


- Elias



Yup, that's pretty much what *anyone* should suspect.
__________________
perspective is everything
  Reply With Quote
Old 12th March 2013, 12:38 AM   #2048
diyAudio Member
 
Join Date: Jun 2007
Quote:
Originally Posted by WithTarragon View Post
Regarding the issue of similar binaural values for the ceiling and floor reflections: I may might need to disagree with myself. I am still thinking this one through
It is confirmed. I definitely disagree with my self.

At 0 or 180 degrees (front and back), the binaural cues for the direct sound, ceiling bounce, and floor bounce are all the same. However this is a special case. Off axis the "bounce" will not fall along the cone of confusion (for the direct sound). The binaural cues will differ from each other and also differ from the direct sound. The discrepancy gets larger as the sound source get closer to either of these boundaries.

I have admitted my mistake and I now feel better about myself. Insert smiley face somewhere
  Reply With Quote
Old 12th March 2013, 06:00 AM   #2049
Banned
 
Join Date: May 2008
Location: Switzerland
I have to disagree with myself too. The floor and ceiling reflections are not on the cone of confusion. If the ears would be in the floor plane then the floor reflection would be on the cone of confusion.

For a driver at 100cm from the floor, ear height at 95cm and a speaker distance of 346.4cm the interaural time differences are as follows:
Direct sound: 0.25ms
Floor reflection: 0.21ms
Ceiling reflection (ceiling height 2.4m): 0.19ms

Last edited by markus76; 12th March 2013 at 06:17 AM.
  Reply With Quote
Old 12th March 2013, 07:50 AM   #2050
graaf is offline graaf  Poland
diyAudio Member
 
graaf's Avatar
 
Join Date: Jun 2007
Quote:
Originally Posted by WithTarragon View Post
It is confirmed. I definitely disagree with my self.

At 0 or 180 degrees (front and back), the binaural cues for the direct sound, ceiling bounce, and floor bounce are all the same. However this is a special case. Off axis the "bounce" will not fall along the cone of confusion (for the direct sound). The binaural cues will differ from each other and also differ from the direct sound. The discrepancy gets larger as the sound source get closer to either of these boundaries.
which means that...? what are the consequences?
__________________
"high phooey and hystereo" - Yascha Heifetz
  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
Using a diffuser cone for up-firing speakers tspringer99 Multi-Way 19 23rd July 2014 02:04 AM
Floor Standing Speakers. gurpreetsingh Full Range 11 12th June 2012 06:42 AM
side/ rear firing speakers Good/Bad? mcmahon48 Multi-Way 1 6th February 2009 12:28 PM
How far can the driver of a down-firing sub be from the floor? The Paulinator Subwoofers 11 16th May 2007 08:10 PM
Woofer: side firing pair vs front firing? tcpip Multi-Way 13 9th September 2005 02:13 PM


New To Site? Need Help?

All times are GMT. The time now is 09:35 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