Room modes: absortion, bass traps, Eq, speaker position... what really works? - Page 5 - 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 12th February 2013, 10:51 PM   #41
diyAudio Member
 
Join Date: Nov 2012
Location: Brasil
I have a book of Mr. Floyd E. Toole called sound reproduction, and there is a chapter called (Delivering good bass in small rooms) wich I will resume for you in some declaration and observations.

1. The use of multiple subwoofers to manipulate sound fields, controlling the energy delivered to room modes is a recent develpment and the results of this approach are very good.
2. In stereo, it was common to think of a sweet spot, and make all arrangments to have this optimum single listener.
3. However, the existence of standing waves among the roo mensures that other seats experience difference bass.
4. To deliver a good bass to several listeners, the room resonances must be physically manipulated.
5. Acoustic: attacks the problem with absortion
6. Absortion is Always a good idea but it’s difficult.
7. The absortion material has to be placed away from the room boundaries ato ne-quarter the wavelenght (30Hz 2.9meters!)
8. at the corners “bass traps”do not work because there is located the max sound pressure, not particle velocity.
9. There are two ways to vary the amount of energy transfered from loudspeakers tom odes:
a. Locate the subwoofer near a pressure minimum in the offending standing wave
b. Use 2 or more subs to drive the standing waves constructively or destructively. 2 subwoofers connected in parallel, one in each side of a null will destructively drive the mode; positioned two nulls apart, the same subs will amplify the mode
10. The improvement of seat-to-seat bass variations of using multiple subwoofers is vey small when using more than 4.(this was tested buy a Harman guy, using from 1 to 5000 subs in a room)
11. The best subs position using two is one at the middle of the front wall and the other in the opposite back wall; using 4 is one at each corner, or one at the middle of each wall
12. Two midwall subs Works as well as four subs

That’s it.
Now let's hear the GURUS.
  Reply With Quote
Old 12th February 2013, 11:23 PM   #42
45 is offline 45  Italy
diyAudio Member
 
45's Avatar
 
Join Date: Dec 2008
Location: UK
Quote:
Originally Posted by 1audiohack View Post

Using a frequency domain solution for a time domain problem is at best a bandaid
Well said!
Some people do not realize it is not correct putting the listener out of the equation!
They don't realize the hypothesis for applying a Fourier transform is violated when the listener is fully part of the chain.
In such case they equalize....
  Reply With Quote
Old 12th February 2013, 11:44 PM   #43
45 is offline 45  Italy
diyAudio Member
 
45's Avatar
 
Join Date: Dec 2008
Location: UK
Quote:
Originally Posted by murillollirum View Post
my room is very small for a 15 inch speaker that I use, the 38Hz - 350Hz is really a problem because of the room modes interaction with the speaker, anyone solved this kind of problem with room treatment or eq? I would like to hear some...
In your place I would exclusively treat the room with acoustically passive solutions (i.e. traps and diffusors using felt and other materials with similar properties). Is the only real solution other then having a better room from the start (which will need a treatment anyway).
  Reply With Quote
Old 13th February 2013, 12:24 AM   #44
gedlee is offline gedlee  United States
diyAudio Member
 
Join Date: Dec 2004
Location: Novi, Michigan
Quote:
Originally Posted by murillollirum View Post
I have a book of Mr. Floyd E. Toole called sound reproduction, and there is a chapter called (Delivering good bass in small rooms) wich I will resume for you in some declaration and observations.

Now let's hear the GURUS.
That is a good review, but Dr. Toole's analysis is already out of date. There really isn't an "optimum" sub placement if EQ is used, as almost any situation can be made equal to any other as long as there are enough subs. The key is how to determine the parameters for the sub controller. That is where the current state-of-the-art is.
  Reply With Quote
Old 13th February 2013, 01:58 AM   #45
diyAudio Member
 
Join Date: Jan 2003
Location: Courtice, Ontario
Can someone point to a Full Range Frequency Response Curve for DBA?
Is the Bass Shelved?

Also How does the Bass Sound with DBA..
Listenening goes beyond measurement.. Does bass sound clean?
  Reply With Quote
Old 13th February 2013, 02:25 AM   #46
gedlee is offline gedlee  United States
diyAudio Member
 
Join Date: Dec 2004
Location: Novi, Michigan
Quote:
Originally Posted by Joel Wesseling View Post
Listenening goes beyond measurement..
No it doesn't. No data means you are guessing and completely at the mercy of your biases.
  Reply With Quote
Old 13th February 2013, 03:43 AM   #47
diyAudio Member
 
Join Date: Jan 2003
Location: Courtice, Ontario
Quote:
Originally Posted by gedlee View Post
No it doesn't. No data means you are guessing and completely at the mercy of your biases.
I wasn't meaning data isn't important.. Data is and the results are heard.

I was inferring that the music signal played through a system and some of the sonic charateristics go beyond what can be shown in a measurements..
  Reply With Quote
Old 13th February 2013, 04:17 AM   #48
diyAudio Member
 
Join Date: May 2010
Location: MN
Quote:
Originally Posted by Joel Wesseling View Post
I was inferring that the music signal played through a system and some of the sonic charateristics go beyond what can be shown in a measurements..
Does that conversation really need to start up here? I'm talking to everyone, not just Joel. In principle, it's absurd to suggest there are things heard that can't be measured. The ability to hear is not fully understood, but the input the ear receives is nothing terribly mysterious, and that's what we are working on. In practice, you can suggest that we don't know what to measure or how, but this is not worth discussing unless you have a case where two things sound demonstratively different and measure the same. I'm not aware of that existing when it comes to in-room bass, but few of us have the capability and motivation to measure it properly. If you're interested in hearing subjective reports, just say that. You don't need to justify your interest in hearing what people have to say.

Last edited by dumptruck; 13th February 2013 at 04:19 AM.
  Reply With Quote
Old 13th February 2013, 06:38 AM   #49
Banned
 
Join Date: May 2008
Location: Switzerland
Quote:
Originally Posted by Joel Wesseling View Post
Can someone point to a Full Range Frequency Response Curve for DBA?
Is the Bass Shelved?

Also How does the Bass Sound with DBA..
Listenening goes beyond measurement.. Does bass sound clean?
Full range? Like any distributed sub solution, DBA is for frequencies <100Hz.
For data follow the link I've posted earlier.
How does it sound? Put a subwoofer in the near field and you'll get an idea.
  Reply With Quote
Old 13th February 2013, 06:52 AM   #50
Banned
 
Join Date: May 2008
Location: Switzerland
Quote:
Originally Posted by 45 View Post
Well said!
Some people do not realize it is not correct putting the listener out of the equation!
They don't realize the hypothesis for applying a Fourier transform is violated when the listener is fully part of the chain.
In such case they equalize....
Care to elaborate?
  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
Simulating bass response with duct and speaker position ashok Multi-Way 15 17th August 2012 10:37 PM
Calling BudP - enabl vs room modes just a guy Full Range 14 26th August 2009 11:57 AM
Planar bass wave to take care of room modes ?? JinMTVT Subwoofers 12 4th October 2007 05:15 PM
DBA (dual bass arrays) and active bass traps capslock Subwoofers 3 20th August 2006 12:52 PM


New To Site? Need Help?

All times are GMT. The time now is 12:18 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