Thin and tall VS wide and short enclosure - 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 16th January 2009, 05:42 PM   #1
limono is offline limono  United States
diyAudio Member
 
Join Date: Mar 2007
Default Thin and tall VS wide and short enclosure

Hi there
After 8 years I was able to buy a pair of Audax HM170ZO woofers and complete a kit I started collecting parts for many years ago (kit origins from 94'). My tastes changed a lot and it won't be my main speaker (I'm into horns and triode amps now). I have an enclosure of required volume (30L ) but the original design calls for slim tall tower enclosure 206mm wide and 1000mm tall with port on the back .What I have is solid vintage JBL cab 325mm wide and 600mm tall with front port (accidentally the diameter of port is almost there -1mm) I could fairly easy use the back of enclosure as a front and even move the alnico ribbon on the top of the cab (but would rather keep it in for practicality purpose)
My main question is how the characteristics of the speaker will change due to baffle difference and if it's predictable at all.
Crossover is 12dB on both slopes at 3khz.
Thanks & regards, L
Attached Images
File Type: jpg dscn0374.jpg (16.7 KB, 218 views)
  Reply With Quote
Old 16th January 2009, 07:12 PM   #2
diyAudio Member
 
Wayne Parham's Avatar
 
Join Date: Feb 2004
One difference is how the internal standing waves line up. In a vented cabinet, there are two mechanisms that cause acoustic resonance: Helmholtz resonance and standing wave resonance. Standing wave modes can sometimes be ignored in small cabinets with small ports because the internal standing waves are high in frequency and easy to damp with internal stuffing. But in a larger box, these pipe modes become significant. They line up at bass, midbass and low midrange frequencies that aren't easily damped with acoustic insulation lining the walls. Sometimes more filler is enough, or possibly a sheet or two spanning the cross-section. Often times, driver and port placement can be used to good effect. It is important to know where the standing waves line up to know for sure.

The bottom line is a tall thin cabinet acts as both a transmission line and a bass-reflex cabinet. It has Helmholtz resonance and pipe mode resonance. You'll see both with an impedance sweep. You can also model both effects, and Martin King's spreadsheets do that very well. Grab a copy of his spreadsheets and play with them a bit and you'll see what I mean.
  Reply With Quote
Old 16th January 2009, 09:12 PM   #3
limono is offline limono  United States
diyAudio Member
 
Join Date: Mar 2007
Thank You Wayne
Access to Martins spreadsheet is restricted. I have original kit literature publisched in German "Klang & Ton" with impedance graph (very small unfortunately) Impedance graph has two steep peaks at ~20-25hz and 60Hz.
My German is very very rusty but seems like the tuning (Q=1.4) is right at woofer FS which is 32Hz. The project was launched in 94' when slim tower designs became very fashionable .Also port on the back (dia 70mm with 230mm length) is in the middle of the cab hight so it doesn't work quite like MLTL.
Regards, L
  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
Coral Beta 10 in thin-walled enclosure (Rondo) RemcoB Full Range 0 27th July 2008 09:56 PM
Hemp FR8C in Wide and Thin (Mileva?) fcj Full Range 6 22nd May 2007 10:17 PM
long-thin vs fat-short TL Henkjan Full Range 26 22nd October 2006 07:54 PM
9' tall and 12' wide..... Altec A1 V.O.T.T. RacerXtreme Multi-Way 10 22nd May 2005 11:22 PM
Dimensions to make the enclosure look tall and slim. rakeshln Multi-Way 15 8th July 2004 03:12 AM


New To Site? Need Help?

All times are GMT. The time now is 09:55 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