
Home  Forums  Rules  Articles  The diyAudio Store  Gallery  Blogs  Register  Donations  FAQ  Calendar  Search  Today's Posts  Mark Forums Read  Search 
MultiWay 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 

Thread Tools  Search this Thread 
17th September 2003, 09:47 AM  #1 
diyAudio Moderator Emeritus
Join Date: May 2003
Location: UK

Golden ratios and standing waves
Based on the consensus that: enclosures dimensions should optimally be derived using golden ratios to reduce standing wave effects, I have a question...
My enclosure volume is approx. 98l which I'm building into 244x418x962mm enclosure. Using W=v/f, I caluclate standing waves at: 1393 Hz 813 Hz 353 Hz If a golden ratio is used to derive box size: 280x467x747mm, then standing waves exist at: 1214 Hz 728 Hz 455 Hz The offending frequencies are very close and I see no reason to closely adhere to the golden ratios? ( or have I missed something ) I was going to asymmetrically fill three walls with fiberglass to compensate. Any comments? 
17th September 2003, 10:15 AM  #2 
diyAudio Member
Join Date: Sep 2002
Location: Australia

Sorry to be a cynic, but what consensus? I find the Golden Ratio/Fibonacci etc interesting as an example of coincidental math, but some of the effects ascribed to it by Cardas and others just strike me as voodoo for impressionable audioholics.
Still, it can't hurt. Cheers Steve
__________________
http://cargocollective.com/stevedodd...geoftheNerd 
17th September 2003, 10:32 AM  #3 
diyAudio Member
Join Date: Jun 2001
Location: UK

This may be useful
http://www.acoustica.org.uk
Click on 'speaker positioning' and locate the Excel Spreadsheet, it may help analyse the issues. Andy. 
17th September 2003, 11:11 AM  #4  
diyAudio Member
Join Date: Jun 2002
Location: Melbourne, Australia

X^2=X+1. 1/X=X1 Mmmm....
My opinion is that the golden ratio is of better use for the external dimensions of the box so that it looks "right".
Quote:
__________________
Bestever T/S parameter spreadsheet. http://www.diyaudio.com/forums/multi...tml#post353269 

17th September 2003, 11:33 AM  #5 
diyAudio Moderator Emeritus
Join Date: May 2003
Location: UK

Just had a look at that spreadsheet. Looks like what I caluclated are actually second order harmonics, the fundamental freq's being half my calculations. How does each harmonic affect the sound  to what degree in amplitude?
At the moment, I think that all rectangular enclosures suffer more or less equally (irrespective of whether the dimensions are golden ratiofied) and that the important thing is to make sure each dimension is (assuming all parallel walls) different  to avoid adding to another standing wave. Agree? Edit: By looking at the harmonics (occuring at each doubling of the fundamental) I've just realised that you need to avoid enclosure dimensions that are multiples of others, as the harmonics will reinforce each other. I think I may have just justified the reasoning for golden ratios 
17th September 2003, 12:18 PM  #6 
diyAudio Member
Join Date: Apr 2003
Location: Hamilton

Excuse my ignorance, I'm still in the early stages of learning this stuff, but I've been wondering for a while; Doesn't using non parallel sides in an enclosure pretty much deal completely with this problem? I'm sure it's just not that simple, or else you would see no rectangular boxes and yet they abound.
Chris 
17th September 2003, 12:32 PM  #7  
diyAudio Member
Join Date: Jul 2002
Location: Vacation Land

Quote:
__________________
Michael Chua 

17th September 2003, 12:34 PM  #8  
diyAudio Moderator

Quote:
Steve, you've apparently had my house bugged. Quote:
__________________
“Instead of Rational Law, objective truths perceptible to any who will undergo the necessary intellectual discipline, Knowledge will degenerate into a riot of subjective visions. . ."  Auden 

17th September 2003, 01:06 PM  #9  
diyAudio Moderator Emeritus
Join Date: May 2003
Location: UK

mcp, here's are the standing wave modes for my current design. I see issues with (for example) the 3rd harmonic (height) and the fundamental (width) reinforcing each other. Are these the problems you were seeing?
It seems clear to me now that using the golden ratios in my design would have resulted in much less overlap of standing waves harmonics. I'm convined of this reasoning now, though I have no idea how much affect this has Quote:


17th September 2003, 02:11 PM  #10  
diyAudio Member
Join Date: Jul 2002
Location: Vacation Land

Quote:
__________________
Michael Chua 

Thread Tools  Search this Thread 


Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Minimising standing waves  GerhardW  MultiWay  13  2nd September 2008 07:43 PM 
Standing waves, anyone willing to experiment ?  jay1st  MultiWay  4  10th February 2008 01:33 AM 
Low resonance and standing waves?  Audist  MultiWay  3  6th November 2005 03:29 AM 
standing waves and cancellation & exageration ?  lolojr1  Subwoofers  13  19th July 2005 05:24 PM 
Standing waves again...  Vikash  MultiWay  4  3rd June 2004 11:25 PM 
New To Site?  Need Help? 