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

Why is floor bounce mostly ignored in commercial speakers??
Why is floor bounce mostly ignored in commercial speakers??
Why is floor bounce mostly ignored in commercial speakers?? 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 2nd December 2019, 02:21 PM   #11
Think is offline Think  Netherlands
diyAudio Member
 
Join Date: Nov 2017
Location: Den Haag, Holland
Why is floor bounce mostly ignored in commercial speakers??
And ceiling bounce? Room modes, corner and room gain? Power compression, off axis response and the rest I forget .......

Because just power consumption, looks and size matter if you don't have any practical knowledge / wisdom about speakers.

And using them right, speaker setup, is just a important as the speakers.


Speaker are seldom setup correct among audiophiles, in venues, at festivals, concerts (U2 Live in Brisbane Horrible sound quality) and at EDM dance parties spending lots of cash.
  Reply With Quote
Old 2nd December 2019, 02:31 PM   #12
Defo is offline Defo  Norway
diyAudio Member
 
Join Date: Nov 2008
Quote:
Originally Posted by Sixto View Post
Ok, so if we had an ideal situation, with a 3-way floor-stander and a low enough W-M crossover... how far would/should one place the mid from the floor to avoid floor-bounce? I'll assume an 8' tall ceiling for this exercise. If a 2" tweeter with a 3-1/2" face plate wants to be centered at seated ear height roughly 45" high, then place a 6" mid as close to that as possible. That places the Mid center at around 40" above the floor. (8" below the midpoint between floor and ceiling) Does that reduce the floor bounce enough, or is some device like MTM configuration, or a horn, or an angled baffle required to control vertical directivity further? I'm assuming that floor bounce can't be avoided for the woofers, so any size and height that works below that should be fine. Also, we'd need to place the vertical driver center at least 3' to 4' far from a wall, or toe it in to avoid wall bounce, right?

Is this what we're talking about, or am I missing something? Just looking to get some concrete recommendations, and reasons for them from this thread. Thanks! Six.
Using a simple calculator: Floor/Ceiling Reflection Calculator

Woofer placed 25 cm above floor equals ~1 KHz.
Mid placed 100 cm above floor equals 250 Hz.
Meaning a XO at 500 Hz should leave most of the bounce out of the passband for both drivers.

The new beta version of XSim also works well in simulating both floor and ceiling bounce with different driver placements and XO's.
  Reply With Quote
Old 2nd December 2019, 02:51 PM   #13
Sixto is offline Sixto  United States
diyAudio Member
 
Join Date: Dec 2014
Location: Minneapolis, MN
Quote:
Originally Posted by Defo View Post
Mid placed 100 cm above floor equals 250 Hz.
Meaning a XO at 500 Hz should leave most of the bounce out of the passband for both drivers.
100 cm = 39.37" so we're in the same ballpark, but the XO at 500 feels high to me. What other options are there if one wanted to cross at 300 Hz?
Six.
  Reply With Quote
Old 2nd December 2019, 02:58 PM   #14
krivium is offline krivium  France
diyAudio Member
 
Join Date: Oct 2009
^: SBIR calculator

Quote:
Originally Posted by Sixto View Post
Does that reduce the floor bounce enough, or is some device like MTM configuration, or a horn, or an angled baffle required to control vertical directivity further? I'm assuming that floor bounce can't be avoided for the woofers, so any size and height that works below that should be fine.
Yes vertical aligned configuration can help to 'reduce' the floor bounce effect. It does as the drivers have different pathlength they will exhibit different 'suck out' ( notch) frequency.
Once summed acoustically instead of one deep notch you then face three less severe ones spanned over a wider freq range.

The point being to find a sweetspot versus the physical dimension of drivers, box conxtraints and frequency of interest ( to mitigate the notch).

You can use FIR in tandem with vertical aligned drivers to have controlled vertical directivity too : Horbach-Keele filter is all about that.

Horn or waveguide helps with controled vertical directivity but it doesn't garantee you it won't happen ( it is one thing some of MEH ( synergy) builders discovered).

Floor ( or ceiling or walls) bounce can't be avoided, this is the nature of reproduction within a room.

Last edited by krivium; 2nd December 2019 at 03:04 PM.
  Reply With Quote
Old 2nd December 2019, 06:44 PM   #15
boswald is offline boswald  United States
diyAudio Member
 
Join Date: Jun 2014
Why is floor bounce mostly ignored in commercial speakers??
Go to classicspeakerpages(.net?).
There are two forms of Roy Allison's explanation of boundary reflections(incl floor bounce-induced cancellation). The short version is in the Allison One Series brochure(3 pgs or so).
The long form is fourteen pages with examples of what doesn't work(and why) as well as his solutions, worth reading.


By the way, he kept the woofers close to the floor, crossed at 300, so your idea is in the ballpark.
  Reply With Quote
Old 2nd December 2019, 07:21 PM   #16
rayma is offline rayma  United States
diyAudio Member
 
Join Date: Apr 2011
Quote:
Originally Posted by boswald View Post
he kept the woofers close to the floor, crossed at 300, so your idea is in the ballpark.
Also the Snell Type A.
  Reply With Quote
Old 2nd December 2019, 07:34 PM   #17
system7 is offline system7  United Kingdom
diyAudio Member
 
system7's Avatar
 
Join Date: Aug 2008
Location: Portsmouth UK
This floor bounce, or Allison effect is all well and good, but what does it mean in practise?

Stuff like the Allison 1 loudspeaker, at least according to Roy himself:
A Glorious Time: AR's Edgar Villchur and Roy Allison Allison Part 1 | Stereophile.com

Click the image to open in full size.

stereonomono - Hi Fi Compendium: Allison model ONE

Of course it don't mean a thing without a crossover:

Click the image to open in full size.

Which ends up like this, I expect:

Click the image to open in full size.

Roy Allison was not only a believer in mounting the bass close to a boundary. He also thought wide dispersion mattered. His speakers actually used those horrible room reflections for the overall sound. He might have been onto something with this expensive approach. The beauty of diy is you can try ideas, and either fly or crash and burn!

I'd certainly like to try the IC20:

Click the image to open in full size.

A beauty, IMO. Much to enjoy there.
__________________
"Per ardua, ad astra." Best Regards from Steve in Portsmouth, UK.
  Reply With Quote
Old 3rd December 2019, 04:34 AM   #18
Sixto is offline Sixto  United States
diyAudio Member
 
Join Date: Dec 2014
Location: Minneapolis, MN
Quote:
Originally Posted by Sixto View Post
P.S. just measured my B&W's and the mid is at 35.5" from the floor, also my Ohm 2's are a different bird (Omnis with a vertical cone aiming down) They have the top of the wood base at 2' above the floor and the top of the metal canister 6" above that. I should measure the B&W's where they are, and then try again with a 10" riser and see what REW shows.
So, below is a comparison using REW of my B&W DM640 on the floor 1/24th octave smoothing. (Midrange at 35.5" above the floor (Green) and with a 12" riser (Red) Microphone was at 45" above floor 8' away which is the main listening position. Speaker is near the front-right corner of the room, the room has a 9' ceiling, nearest wall to the microphone is 6' away to the right, the wall to the left is 8' away.

Looks to me like I should be getting some 12" risers permanently, since the red trace has a 5db swing (flatter) between 200 and 2000 hz vs a 10 db swing for the green trace. I'm relatively new at generating and interpreting graphs, but it seems that there is less room interaction to the midrange with the midrange 12" higher (at the same height as my ears) which bears the OP's hypothesis.

Comments? Sixto. - still learning how to attach images inline.

Why is floor bounce mostly ignored in commercial speakers??-driver-height-comparison-jpg
Attached Images
File Type: jpg Driver Height comparison.jpg (61.6 KB, 319 views)

Last edited by Sixto; 3rd December 2019 at 04:53 AM. Reason: Added image
  Reply With Quote
Old 3rd December 2019, 04:53 AM   #19
DMLBES is offline DMLBES
diyAudio Member
 
Join Date: Mar 2017
IMO acoustic treatments like Auralex isolation pads used directly under speaker or subwoofer works great.
  Reply With Quote
Old 3rd December 2019, 01:51 PM   #20
Sixto is offline Sixto  United States
diyAudio Member
 
Join Date: Dec 2014
Location: Minneapolis, MN
Default Thank you!

Quote:
Originally Posted by boswald View Post
Go to classicspeakerpages(.net?).
There are two forms of Roy Allison's explanation of boundary reflections(incl floor bounce-induced cancellation). The short version is in the Allison One Series brochure(3 pgs or so).
The long form is fourteen pages with examples of what doesn't work(and why) as well as his solutions, worth reading.
Thank you for this information! Here is a link to the longer article: Technical Articles by Roy F. Allison | The Classic Speaker Pages

Sixto
  Reply With Quote

Reply


Why is floor bounce mostly ignored in commercial speakers??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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Why is floor bounce considered only a bass issue? Defo Multi-Way 67 23rd September 2019 05:04 PM
Woofer placement and floor bounce sfdoddsy Multi-Way 1 9th October 2015 03:49 PM
Audibility of floor bounce? mlee Multi-Way 15 4th September 2014 04:48 PM
How to calculate floor bounce reflection(cancellation) jtsaudio Multi-Way 16 7th August 2014 09:47 PM
HOw close does driver need to be to floor to avoid floor bounce? Kanga Multi-Way 8 24th April 2003 07:09 AM


New To Site? Need Help?

All times are GMT. The time now is 11:56 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