F3 - 35.5Hz & Fb - 35.3Hz??

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=49557
Printed Date: May 09, 2025 at 6:23 PM

Topic: F3 - 35.5Hz & Fb - 35.3Hz??

Posted By: nickvr
Subject: F3 - 35.5Hz & Fb - 35.3Hz??
Date Posted: February 07, 2005 at 1:27 PM

Hi. I get the above reading from WINIsd when calculating port length etc. for my enclosure. This doesn't look ok to me, will this work? The -3db (F3) point seems to close to Fb (even little above Fb!)... I know the box is below spec however I cannot increase the size of the box. Is it more efficient to rather port for higher freq i.e. Fb = 45Hz and thus ensure Fb at 0db and F3 at 39Hz?? I'm seeking lowest feasible tight bass

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Nick

Replies:

Posted By: DYohn
Date Posted: February 07, 2005 at 3:15 PM

What is the Qes of the speaker?

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Posted By: nickvr
Date Posted: February 07, 2005 at 6:45 PM

QES=0.560, FS=31.7, Freq Resp = 18Hz - 1000Hz, Dia = 247mm, Xmax=8.6mm, QMS=38.54, QTS=0.550 & VAS = 28.05l. Thanks

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Nick

Posted By: DYohn
Date Posted: February 07, 2005 at 8:50 PM

With these parameters, it tells me the speaker is much better suited for a sealed enclosure than a vented one. The EBP comes out to 62.64 and the Qts is >0.4. I'd put this driver in a sealed system at 1.5 cuft. If you really want to vent it, you'll want to target 2.75 cuft and a Fb of 23.08Hz (port diameter 2", length 4.3")

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Posted By: Steven Kephart
Date Posted: February 07, 2005 at 9:16 PM

We have found that WinISD is way off when it comes to port recommendations. I recommend using the manufacturers recommendations instead. Or of course DYohn's. posted_image

Steven Kephart

Adire Audio

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