Is quarter-wave modeling relevant in a sealed cabinet? - diyAudio
Go Back   Home > Forums > Loudspeakers > Full Range

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 3rd June 2015, 08:43 PM   #1
diyAudio Member
 
brucegseidner's Avatar
 
Join Date: May 2009
Default Is quarter-wave modeling relevant in a sealed cabinet?

I have attempted a search of quarter-wave and sealed cabinets but am only finding information relevant to reflex and horn enclosures. I am convinced I have seen the recommendation to take quarter-wave dynamics, well wave dynamics, into consideration in a sealed enclosure. In effect, not taking this into consideration does not stop the dynamic. It is only an uncontrolled dynamic if not considered in the design.

Conceptually, I understand how the quarter-wave is used to design BR and horn enclosures and how I can achieve bass extension armed with the MJK tables for example.

But I don't get how this is relevant to the dimensions of a sealed enclosure that is properly stuffed and damped internally.

I get that some shapes are more vulnerable to standing waves of all sorts. But is there some ratio of a rectangle that takes the dynamics of quarter-wave into account, relevant to the tuning of a sealed enclosure?

Last edited by brucegseidner; 4th June 2015 at 02:12 AM.
  Reply With Quote
Old 3rd June 2015, 08:59 PM   #2
xrk971 is online now xrk971  United States
diyAudio Member
 
xrk971's Avatar
 
Join Date: Oct 2012
Location: Virginia
If the sealed cabinet is long in aspect ratio and length coincides with frequencies of interest - then yes. It is half wave though and not quarter wave as the boundary condition for quarter wave is closed-open whereas half wave is closed-closed for sealed. This is in fact how I modeled the sealed tapered spiral TL I call the Nautaloss.

The Nautaloss Ref Monitor

The Dagger is another short sealed TL that I use in my reference monitor

10F/8424 & RS225-8 FAST Ref Monitor

Basically, you try to set the length and damping and taper in such a way to minimize the resonance modes in a sealed enclosure. In small prismatic enclosures like typical speaker boxes, the half wave resonance is what is responsible for the mid frequency coloration if not properly damped with padding in the enclosure. Take a typical box that is 8 in deep, will have coloration at a half wave corresponding to 8 in or 20cm or 855Hz. If you avoid parallel walls, this helps prevent this mode from being a sharp peak or dip.

Last edited by xrk971; 3rd June 2015 at 09:05 PM.
  Reply With Quote
Old 4th June 2015, 02:06 AM   #3
diyAudio Member
 
brucegseidner's Avatar
 
Join Date: May 2009
The threads you referenced are incredible, both for their length and community involvement. They are a lot to take in, and now I am thinking of re-doing my home theater with those 2-ways!

Thank you for your support. Let me digest this and come back for more. But these threads establish reference that is enormously valuable to hobbyist types like myself. Technical/math people sometime take these capacities for granted and imagine anyone with some effort can master these models. I have been around these concepts for a long time and still don't have the technical chops. Those of us without those capacities really rely on your support and appreciate the help.

I wish I could knock out some cab's for ya in return. The wood worker in me winces a bit seeing your ingenuity and talent going into pink foam projects. I like pink foam. It ends up on the garage floor where I knock down sheet goods. LOL But what a cool way to experiment and create!

Cheers and thanks,

Bruce

Last edited by brucegseidner; 4th June 2015 at 02:09 AM.
  Reply With Quote
Old 4th June 2015, 02:39 AM   #4
xrk971 is online now xrk971  United States
diyAudio Member
 
xrk971's Avatar
 
Join Date: Oct 2012
Location: Virginia
Quote:
I wish I could knock out some cab's for ya in return. The wood worker in me winces a bit seeing your ingenuity and talent going into pink foam projects. I like pink foam. It ends up on the garage floor where I knock down sheet goods. LOL But what a cool way to experiment and create!
I would love real plywood boxes for my monitors! If you are serious about building I can get you plans.

Thanks for the kind words - there are a lot of people who help me out with the designs and debugging and refining.
  Reply With Quote
Old 4th June 2015, 02:59 AM   #5
diyAudio Member
 
brucegseidner's Avatar
 
Join Date: May 2009
I am absolutely serious. It is not hard to score up the ply, spatula in construction adhesive and then form the tear drop around sacrificial foam ribs or ply ribs that strengthen the cab. It is a little messy when the adhesive is squeezed out but not too bad. Not that much different than when you are gluing up a panel. Masking tape and those nylon straps keep it tight while it dries. And there is none of the waste that is the byproduct of these segmented CNC teardrop designs. I will stay in touch and should be set up to work some wood after the Tour de France. These KEF E305's I am running for HT are utterly "meh" with a gapping hole in the lower midrange. I was going to build a different 2-way but priced the one you designed and like it better. So I will build them in August to replace the KEF's. Once set up it is cake to knock out as many as I like. They are small and shipping flat packs should not be that expensive. We will work it out. Cheers!
  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
Quarter Wave Recommendations Kofi Annan Multi-Way 42 20th April 2015 08:03 PM
Quarter Wave TL's and various Questions. demon2091tb Multi-Way 4 22nd November 2006 06:19 PM
large quarter wave, HELP!! psychosteve Multi-Way 5 8th October 2004 02:08 PM
Martin King: Is it just me or quarter-wave.com is down? Thanks JC Fardo Multi-Way 7 12th September 2003 11:15 PM


New To Site? Need Help?

All times are GMT. The time now is 01:42 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2015 DragonByte Technologies Ltd.
Copyright 1999-2015 diyAudio

Content Relevant URLs by vBSEO 3.3.2