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Date: Sat, 12 Oct 96 17:32:02 -0700
From: "Victor J. Albert" <victora@mda.vnd.TEK.COM>
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bigdan@kreft.net (D.Kreft) wrote:
>In article <Pine.BSI.3.95.961011121200.26344B-100000@laurel.us.net>, David
>Studenick <rooster@us.net> wrote:
>
>> Question for Steve and Manville,
>
>Steve is out of town and I'm not sure if Manville is going to have the
>time to check usenet so pardon me if I offer unsolicited assistance.
>
>
>> When you recommend box volumes, what is the range of Qtc you use? 
>
>Generally speaking, for car audio use, JL Audio recommends that Qtc's not
>rise above 1.1 or so...they can be as low as the consumer wishes.
>
>HOWEVER (big "however" here)....it doesn't mean anything to choose a Qtc
>without also considering the f3 (-3dB down point) of the system; likewise
>it makes no sense to study f3's while ignoring Qtc's.  
>
>Which would you find more desireable, having a Qtc of .707 combined with
>an f3 of 50 Hz or a Qtc of .9 with an f3 of 38Hz?  I don't know about you,
>but I'd be heading straight for the .9/38Hz myself (assuming we're looking
>for a SUBwoofer system here).
>
>High Q's combined with high f3's lead to peaky, boomy, nasty,
>gawd-I-wanna-puke bass where low Q's combined with too-low f3's tend to
>lead to heavy, lifeless, dead-in-the-water type bass.  The idea is to
>reach a happy middle ground.
>
>For most vehicles it's pretty safe to shoot for f3's between 38 - 45 Hz in
>sealed cabinets with Qtc's in the range of .8 to 1.0 ... that's what the
>boys at JL Audio have found to work pretty well for *most* situations (not
>all).
>
>
>> it varies depending on the application, etc...  But I am specifically
>> concerned with the 10W6s.  I used the recommended enclosure volume for
>> them (I think it was 0.875 cu. ft. each <?>), but I'm too lazy to solve
>> all the damn equations in Dicakson for Qtc.  Besides, I don't have the T-S
>> params. handy.
>
>A 10W6 in ________ cu. ft sealed will yield a Qtc of __________ .
>            .5                                           1.02
>            .625                                          .94
>            .75                                           .87
>            .875                                          .82
>
>For most applications, the .625 or the .75 is recommended.
>
>I hope this helps.
>
>You can reach Steve directly at sTurrisi@jlaudio.com, ya know.  ;-)
>
>Dan Kreft
>Disgruntled Postal Worker #4578
>www.kreft.net