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

Is there a Golden Ratio?
Is there a Golden Ratio?
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 September 2018, 04:24 PM   #1
nigelb63 is offline nigelb63
diyAudio Member
 
Join Date: Sep 2013
Default Is there a Golden Ratio?

Very simply; on the subject of baffle diffraction, is there anything that comes close to a golden ratio for baffle width over woofer diameter?
  Reply With Quote
Old 12th September 2018, 04:36 PM   #2
mbrennwa is offline mbrennwa  Switzerland
diyAudio Member
 
mbrennwa's Avatar
 
Join Date: Mar 2005
Location: Zurich, Switzerland
I don't understand the question. Just multiply the woofer diameter by 1.62 to get your golden baffle width. That's pretty close to 1.61803398875... what am I missing?
__________________
[ audioroot.net | hifibau.ch ]
  Reply With Quote
Old 12th September 2018, 07:05 PM   #3
cyberstudio is offline cyberstudio  Canada
diyAudio Member
 
Join Date: Mar 2018
Location: Burnaby, BC
The golden ratio is chosen for visual appeal. In practice fabricating a baffle with a true irrational number as its dimensions is impossible. For sonic benefits what you are really after is that for the two harmonic series that results in the two dimensions, none of the upper harmonics coincide until it is very high up, in other words the two tones from the two dimensions are 'dissonant'. 5:8 is actually a minor 6th. I surmise (haven't tried) that root 2 (1.414) might sound good. Even if we are imprecise and we round to 1.4 it still does not sound like any regular musical interval. By this logic 1.3 or 1.7 would sound good too.
[EDIT: I was thinking out loud and as I think more root 2 is a diminished fifth which would suggests 2 keys to gravitate to and a good speaker dimension ratio must be totally out of tune.]

Last edited by cyberstudio; 12th September 2018 at 07:12 PM.
  Reply With Quote
Old 12th September 2018, 07:19 PM   #4
danny_66 is offline danny_66  Belgium
diyAudio Member
 
danny_66's Avatar
 
Join Date: Jun 2005
Location: Lierde
Try boxnotes it will show the resonances depending on the dimensions of a cabinet.
__________________
My RefSpeaker
  Reply With Quote
Old 12th September 2018, 09:12 PM   #5
system7 is offline system7  United Kingdom
diyAudio Member
 
system7's Avatar
 
Join Date: Aug 2008
Location: Portsmouth UK
As far as bafflestep goes, the width of the cabinet is usually the main event.

Bear in mind most drivers are designed to work in a cabinet a bit wider than the driver.

All this standing waves and modes and Golden Ratio business is a bit overrated IMO. At low frequencies the main event is the volume of the box.

At high frequencies, the speaker is so inefficient it hardly matters. Think 2% efficiency for most drivers due to the very poor cone to air coupling.

The surprise? The classic 2 foot by 1 foot by 1 foot cabinet is hard to beat. It just works well in the Super HL5+ according to Alan Shaw of Harbeth. He uses 12mm HDF with panel damping in the BBC tradition. But 18mm on the front baffle. Very light. A brace across the middle makes sense with a tall cabinet.

Harbeth - Loudspeakers - Super HL5plus - Hifi speaker

The M30.1 is nearer Golden Ratio on front baffle. Looks nice enough. But not actually the 0.618:1:1.618 ratio overall.

Harbeth - Loudspeakers - Monitor 30.1 domestic - Hifi speaker

Good drivers, good crossover and that is 90% of the battle. Good cabinet is the rest.
__________________
Best Regards from Steve in Portsmouth, UK.
  Reply With Quote
Old 13th September 2018, 03:46 AM   #6
norman bates is offline norman bates  United States
diyAudio Member
 
norman bates's Avatar
 
Join Date: Nov 2003
Location: iowa
Diffraction can help with the staggered offsets (tweet to baffle edge).
There are measurements backing it up.

Me, I use foam so I don't worry about it (may get my felt cut some day).

I think golden ratio helps spread out standing waves inside the box.

I had a pioneer b20 in a box with no insulation, not 1 : 1.618 ratios, but 1' deep x 2' wide x 3' tall. Sounded pretty good (minus the honky sound probably created by the big whizzer).
  Reply With Quote
Old 13th September 2018, 09:50 AM   #7
TMM is offline TMM  Australia
diyAudio Member
 
Join Date: Sep 2007
Location: Australia
Send a message via AIM to TMM
You will find that for offset tweeter placement at the top of a tall baffle, the optimal placement is close to golden ratios between the sides and top, with the top having the shortest distance. I.e. Top:side1:side2 = 1:1.618:1.618^2 = 1:1.618:2.618. So if the distance from the tweeter to the top is 1 unit, the distance to the left or right should be 1.618 units and the distance to the right or left should be 2.618 units.

For woofers, generally the bigger the baffle the better to minimise losses due to omni-directional radiation at low frequency. As the size of the cone becomes significant compared to the baffle, the ripple becomes less severe so there is less need to place a woofer offset.
  Reply With Quote
Old 14th September 2018, 12:35 PM   #8
nigelb63 is offline nigelb63
diyAudio Member
 
Join Date: Sep 2013
Quote:
Originally Posted by system7 View Post
As far as bafflestep goes, the width of the cabinet is usually the main event.

Bear in mind most drivers are designed to work in a cabinet a bit wider than the driver.

All this standing waves and modes and Golden Ratio business is a bit overrated IMO. At low frequencies the main event is the volume of the box.

At high frequencies, the speaker is so inefficient it hardly matters. Think 2% efficiency for most drivers due to the very poor cone to air coupling.

The surprise? The classic 2 foot by 1 foot by 1 foot cabinet is hard to beat. It just works well in the Super HL5+ according to Alan Shaw of Harbeth. He uses 12mm HDF with panel damping in the BBC tradition. But 18mm on the front baffle. Very light. A brace across the middle makes sense with a tall cabinet.

Harbeth - Loudspeakers - Super HL5plus - Hifi speaker

The M30.1 is nearer Golden Ratio on front baffle. Looks nice enough. But not actually the 0.618:1:1.618 ratio overall.

Harbeth - Loudspeakers - Monitor 30.1 domestic - Hifi speaker

Good drivers, good crossover and that is 90% of the battle. Good cabinet is the rest.
Hi Steve, talk about a fluke. My cabs are very near to the HLF5+. Mainly because these volts are meaty bastatrds and a 35L sturdy cab has driven the size. I'm using a 16mm solid aluminium baffle. The rest of the cabinet is 18mm with bracing.I'll be using self adhesive bitumen sheets to line the insides.
  Reply With Quote
Old 14th September 2018, 12:43 PM   #9
gabdx is offline gabdx  Canada
diyAudio Member
 
Join Date: Jan 2008
+/- 1 mm with the tweeter has a big impact at 2khz like.... very hard to make a proper speaker
__________________
amplificateurslegrand.ca
  Reply With Quote
Old 14th September 2018, 01:10 PM   #10
nigelb63 is offline nigelb63
diyAudio Member
 
Join Date: Sep 2013
+/- 1mm? Surely a deviation that small can't be audible to the human ear? Especially considering the subjectivity of listening. Some people like to EQ, some like flat, some like bass heavy, some like sibilance. I'm no expert but I can't agree with your statement.
  Reply With Quote

Reply


Is there a Golden Ratio?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
Golden Ratio cyberstudio Multi-Way 52 1st April 2018 05:47 PM
The Golden Ratio of 1.618 PrecisionAudio Multi-Way 43 11th October 2012 03:15 PM
√ instead of the golden ratio Key Multi-Way 19 18th March 2009 09:36 AM
W4-1320SB Golden Ratio BR sharpi31 Full Range 4 8th December 2005 09:50 PM
Golden ratio - Example? icebear Multi-Way 5 17th April 2004 08:40 PM


New To Site? Need Help?

All times are GMT. The time now is 12:27 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki