Menu
Forum
General Car Audio
Subwoofers
Speakers
Amplifiers
Head Units
Car Audio Build Logs
Wiring, Electrical and Installation
Enclosure Design & Construction
Car Audio Classifieds
Home Audio
Off-topic Discussion
The Lounge
What's new
Search forums
Gallery
New media
New comments
Search media
Members
Registered members
Current visitors
Classifieds Member Feedback
SHOP
Shop Head Units
Shop Amplifiers
Shop Speakers
Shop Subwoofers
Shop eBay Car Audio
Log in / Register
Forum
Search
Search titles and first posts only
Search titles only
Search titles and first posts only
Search titles only
Log in / Join
What’s new
Search
Search titles and first posts only
Search titles only
Search titles and first posts only
Search titles only
General Car Audio
Subwoofers
Speakers
Amplifiers
Head Units
Car Audio Build Logs
Wiring, Electrical and Installation
Enclosure Design & Construction
Car Audio Classifieds
Home Audio
Off-topic Discussion
The Lounge
What's new
Search forums
Menu
Reply to thread
Forum
Car Audio Help
Enclosure Design & Construction
Sealed Enclosure Calculations help
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Message
<blockquote data-quote="AznRevlAzn" data-source="post: 623340" data-attributes="member: 557827"><p>ok so i am here at <a href="http://www.diysubwoofers.org" target="_blank">http://www.diysubwoofers.org</a> trying to find out how big of an enclosure my 2 Lanzar MAX12's need.</p><p></p><p>according to the website i need to do this:</p><p></p><p>(Property of <a href="http://www.diysubwoofers.org" target="_blank">http://www.diysubwoofers.org</a> credit goes all to Brian Steele for his work)</p><p></p><p><strong>To determine the box size for a sealed enclosure system, you will need to know the following Theile/Small parameters for the driver: </strong></p><p></p><p><strong>Vas = Equivalent air compliance (litres)</strong></p><p></p><p><strong>Qts = total Q of the driver at Fs</strong></p><p></p><p><strong>Fs = resonance frequency of the driver (Hz)</strong></p><p></p><p><strong> </strong></p><p></p><p><strong>Choose a final Qtc (total Q of system at resonant frequency) for your design. Recommended values for Qtc are from 0.6 to 1.0. Transient response degrades with higher Qtc values, but the power handling of the system increases. A Qtc of 0.7 will usually give pretty good results, but you can use a higher figure if the subwoofer has a low resonant frequency (</strong></p><p></p><p><strong> </strong></p><p></p><p><strong>Then, </strong></p><p></p><p><strong> </strong></p><p></p><p><strong>Qr = Qtc/Qts </strong></p><p></p><p><strong>Vr = Qr^2-1 </strong></p><p></p><p><strong>Vb = Vas/Vr </strong></p><p></p><p><strong>Fb = Qr*Fs </strong></p><p></p><p><strong>F3 = Fb*((1/Qtc^2-2+((1/Qtc^2-2)^2+4)^0.5)/2)^0.5 </strong></p><p></p><p><strong> </strong></p><p></p><p><strong>If Qtc&gt;(1/2)^.5 </strong></p><p></p><p><strong>then dBpeak = 20*log(Qtc^2/(Qtc^2-0.25)^0.5)</strong></p><p></p><p><strong>Else dBpeak = 0</strong></p><p></p><p><strong> </strong></p><p></p><p><strong>where, </strong></p><p></p><p><strong> </strong></p><p></p><p><strong>Vb = net box volume (litres) </strong></p><p></p><p><strong>Fb = box resonant frequency (Hz) </strong></p><p></p><p><strong>F3 = -3dB frequency (Hz) </strong></p><p></p><p><strong>dBpeak = maximum peak or dip in system response</strong></p><p></p><p>1. Now, i take it that the Vb is what i need for the amount of air inside the box. How do i convert that to Cubic Feet? Better yet Cubic Inches?</p><p></p><p>2. If i wanted to make a sealed enclosure that is seperated in 2 sealed compartments that can house 1 subwoofer in each compartment (thus 1 single large enclosure housing 2 subwoofers, do i need to just use the same formula for both sides of the box or will i need a new formula?</p></blockquote><p></p>
[QUOTE="AznRevlAzn, post: 623340, member: 557827"] ok so i am here at [URL="http://www.diysubwoofers.org"]http://www.diysubwoofers.org[/URL] trying to find out how big of an enclosure my 2 Lanzar MAX12's need. according to the website i need to do this: (Property of [URL="http://www.diysubwoofers.org"]http://www.diysubwoofers.org[/URL] credit goes all to Brian Steele for his work) [B]To determine the box size for a sealed enclosure system, you will need to know the following Theile/Small parameters for the driver: [/B] [B]Vas = Equivalent air compliance (litres)[/B] [B]Qts = total Q of the driver at Fs[/B] [B]Fs = resonance frequency of the driver (Hz)[/B] [B] [/B] [B]Choose a final Qtc (total Q of system at resonant frequency) for your design. Recommended values for Qtc are from 0.6 to 1.0. Transient response degrades with higher Qtc values, but the power handling of the system increases. A Qtc of 0.7 will usually give pretty good results, but you can use a higher figure if the subwoofer has a low resonant frequency ([/B] [B] [/B] [B]Then, [/B] [B] [/B] [B]Qr = Qtc/Qts [/B] [B]Vr = Qr^2-1 [/B] [B]Vb = Vas/Vr [/B] [B]Fb = Qr*Fs [/B] [B]F3 = Fb*((1/Qtc^2-2+((1/Qtc^2-2)^2+4)^0.5)/2)^0.5 [/B] [B] [/B] [B]If Qtc>(1/2)^.5 [/B] [B]then dBpeak = 20*log(Qtc^2/(Qtc^2-0.25)^0.5)[/B] [B]Else dBpeak = 0[/B] [B] [/B] [B]where, [/B] [B] [/B] [B]Vb = net box volume (litres) [/B] [B]Fb = box resonant frequency (Hz) [/B] [B]F3 = -3dB frequency (Hz) [/B] [B]dBpeak = maximum peak or dip in system response[/B] 1. Now, i take it that the Vb is what i need for the amount of air inside the box. How do i convert that to Cubic Feet? Better yet Cubic Inches? 2. If i wanted to make a sealed enclosure that is seperated in 2 sealed compartments that can house 1 subwoofer in each compartment (thus 1 single large enclosure housing 2 subwoofers, do i need to just use the same formula for both sides of the box or will i need a new formula? [/QUOTE]
Insert quotes…
Verification
Post reply
Forum
Car Audio Help
Enclosure Design & Construction
Sealed Enclosure Calculations help
Top
Menu
What's new
Forum list
