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
How Off Is RE Calculator??
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="Farva" data-source="post: 4995481" data-attributes="member: 598408"><p>Wow yet another thread on yet another board discussing the accuracy of the <a href="http://reaudio.com/speaker_box/LPort_Box_Calc.html" target="_blank">RE Calculator</a>. First and foremost its off, but not so drastically that will render it useless! For example, say you wanted to build slot port enclosure for an FI Q12 subwoofer. After some thought your initial plan is for 2.3 cuft tuned to 32 hertz.</p><p></p><p>After playing around with it you get 2.459 cuft tuned to 32.026 hertz with 31.25 inches of port before displacements, which you believe should work. Now if you break that down and use WinISD Pro or even any accepted formula (say the one from <a href="http://mobile.jlaudio.com/support_pages.php?page_id=165" target="_blank">JL Audio</a> on Ports) you will get the results below. In this case I just used <a href="http://www.linearteam.dk/default.aspx?pageid=winisdpro" target="_blank">WinISD Pro</a> for the ease of automation of the port length. I also included the equation below if you prefer using good ole mathematics. Even taking the 28.75 total port length into account (end correction adjustment) you will still be off after displacements.</p><p></p><p>Here is design straight from the calculator. (old version 1st new version 2nd)</p><p></p><p><a href="http://i358.photobucket.com/albums/oo23/farvalicious/RE_Calculator/RE_Calc_01b.jpg" target="_blank"><img src="http://i358.photobucket.com/albums/oo23/farvalicious/RE_Calculator/RE_Calc_01.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></a></p><p></p><p><a href="http://i358.photobucket.com/albums/oo23/farvalicious/RE_Calculator/RE_Calc_05b.jpg" target="_blank"><img src="http://i358.photobucket.com/albums/oo23/farvalicious/RE_Calculator/RE_Calc_05.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></a></p><p></p><p>Modeled in SketchUp.</p><p></p><p><a href="http://i358.photobucket.com/albums/oo23/farvalicious/RE_Calculator/RE_Calc_02b.jpg" target="_blank"><img src="http://i358.photobucket.com/albums/oo23/farvalicious/RE_Calculator/RE_Calc_02.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></a></p><p></p><p>Actual port length.</p><p></p><p><a href="http://i358.photobucket.com/albums/oo23/farvalicious/RE_Calculator/RE_Calc_03b.jpg" target="_blank"><img src="http://i358.photobucket.com/albums/oo23/farvalicious/RE_Calculator/RE_Calc_03.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></a></p><p></p><p>The calculator shows 28.75 inches, to account for the end correction, and yes you can see that the actual port length (taking end correction into account) adds up to 28.75 inches.</p><p></p><p>Volume of the enclosure before sub displacement (as you can see all other displacements accounted for i.e. port including end correction).</p><p></p><p><a href="http://i358.photobucket.com/albums/oo23/farvalicious/RE_Calculator/RE_Calc_04b.jpg" target="_blank"><img src="http://i358.photobucket.com/albums/oo23/farvalicious/RE_Calculator/RE_Calc_04.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></a></p><p></p><p>Now take into account the subwoofer displacement (Fi Q has 0.16 cuft). So now your net volume, all displacements taken into account, is 2.2 cuft. Just plug the new variables into <a href="http://www.linearteam.dk/default.aspx?pageid=winisdpro" target="_blank">WinISD Pro</a>, so now your enclosure is actually 2.2 cuft tuned to 34 hertz.</p><p></p><p>Or if you prefer good ole mathematics. (the formula below differs slightly from the one on <a href="http://mobile.jlaudio.com/support_pages.php?page_id=165" target="_blank">JL Audio</a> site, but thats due to the conversion of cubic inches to cubic feet)</p><p></p><ul> <li data-xf-list-type="ul">Fb = 0.159*SQRT[(Av*(1.84*10^8)]/(Vb*1728*[Lv+(0.823*SQRT(Av))])<br /> </li> <li data-xf-list-type="ul">Fb = 0.159*SQRT[(31.25*(1.84*10^8)]/(2.2*1728*[28.75+(0.823*SQRT(31.25))])<br /> </li> <li data-xf-list-type="ul">Fb = 0.159*SQRT(5750000000/126783.36)<br /> </li> <li data-xf-list-type="ul">Fb = 0.159*SQRT(45352.95)<br /> </li> <li data-xf-list-type="ul">Fb = 0.159*212.96<br /> </li> <li data-xf-list-type="ul">Fb = 33.86<br /> </li> </ul><p></p><p></p><p></p><p>So you are off a tenth or so of a cubic foot of airspace and around twoish hertz in resonance, in this case. What does this all mean? Its simple, the calculator is far from accurate but will produce a bassheads daily trunk beater. Which I believe was the intent in the first place. Now get me a d@mn liter of cola, and liter is French for give me some fawking cola!</p></blockquote><p></p>
[QUOTE="Farva, post: 4995481, member: 598408"] Wow yet another thread on yet another board discussing the accuracy of the [URL="http://reaudio.com/speaker_box/LPort_Box_Calc.html"]RE Calculator[/URL]. First and foremost its off, but not so drastically that will render it useless! For example, say you wanted to build slot port enclosure for an FI Q12 subwoofer. After some thought your initial plan is for 2.3 cuft tuned to 32 hertz. After playing around with it you get 2.459 cuft tuned to 32.026 hertz with 31.25 inches of port before displacements, which you believe should work. Now if you break that down and use WinISD Pro or even any accepted formula (say the one from [URL="http://mobile.jlaudio.com/support_pages.php?page_id=165"]JL Audio[/URL] on Ports) you will get the results below. In this case I just used [URL="http://www.linearteam.dk/default.aspx?pageid=winisdpro"]WinISD Pro[/URL] for the ease of automation of the port length. I also included the equation below if you prefer using good ole mathematics. Even taking the 28.75 total port length into account (end correction adjustment) you will still be off after displacements. Here is design straight from the calculator. (old version 1st new version 2nd) [URL="http://i358.photobucket.com/albums/oo23/farvalicious/RE_Calculator/RE_Calc_01b.jpg"][IMG]http://i358.photobucket.com/albums/oo23/farvalicious/RE_Calculator/RE_Calc_01.jpg[/IMG][/URL] [URL="http://i358.photobucket.com/albums/oo23/farvalicious/RE_Calculator/RE_Calc_05b.jpg"][IMG]http://i358.photobucket.com/albums/oo23/farvalicious/RE_Calculator/RE_Calc_05.jpg[/IMG][/URL] Modeled in SketchUp. [URL="http://i358.photobucket.com/albums/oo23/farvalicious/RE_Calculator/RE_Calc_02b.jpg"][IMG]http://i358.photobucket.com/albums/oo23/farvalicious/RE_Calculator/RE_Calc_02.jpg[/IMG][/URL] Actual port length. [URL="http://i358.photobucket.com/albums/oo23/farvalicious/RE_Calculator/RE_Calc_03b.jpg"][IMG]http://i358.photobucket.com/albums/oo23/farvalicious/RE_Calculator/RE_Calc_03.jpg[/IMG][/URL] The calculator shows 28.75 inches, to account for the end correction, and yes you can see that the actual port length (taking end correction into account) adds up to 28.75 inches. Volume of the enclosure before sub displacement (as you can see all other displacements accounted for i.e. port including end correction). [URL="http://i358.photobucket.com/albums/oo23/farvalicious/RE_Calculator/RE_Calc_04b.jpg"][IMG]http://i358.photobucket.com/albums/oo23/farvalicious/RE_Calculator/RE_Calc_04.jpg[/IMG][/URL] Now take into account the subwoofer displacement (Fi Q has 0.16 cuft). So now your net volume, all displacements taken into account, is 2.2 cuft. Just plug the new variables into [URL="http://www.linearteam.dk/default.aspx?pageid=winisdpro"]WinISD Pro[/URL], so now your enclosure is actually 2.2 cuft tuned to 34 hertz. Or if you prefer good ole mathematics. (the formula below differs slightly from the one on [URL="http://mobile.jlaudio.com/support_pages.php?page_id=165"]JL Audio[/URL] site, but thats due to the conversion of cubic inches to cubic feet) [LIST] [*]Fb = 0.159*SQRT[(Av*(1.84*10^8)]/(Vb*1728*[Lv+(0.823*SQRT(Av))]) [*]Fb = 0.159*SQRT[(31.25*(1.84*10^8)]/(2.2*1728*[28.75+(0.823*SQRT(31.25))]) [*]Fb = 0.159*SQRT(5750000000/126783.36) [*]Fb = 0.159*SQRT(45352.95) [*]Fb = 0.159*212.96 [*]Fb = 33.86 [/LIST] So you are off a tenth or so of a cubic foot of airspace and around twoish hertz in resonance, in this case. What does this all mean? Its simple, the calculator is far from accurate but will produce a bassheads daily trunk beater. Which I believe was the intent in the first place. Now get me a d@mn liter of cola, and liter is French for give me some fawking cola! [/QUOTE]
Insert quotes…
Verification
Post reply
Forum
Car Audio Help
Enclosure Design & Construction
How Off Is RE Calculator??
Top
Menu
What's new
Forum list
