How large would a speaker enclosure have to be for it to function as an infinite baffle? And does this eliminate the need for enclosure tuning? As a reference; horn HF, horn MID, 18" cone LF.
How large would a speaker enclosure have to be for it to function as an infinite baffle? And does this eliminate the need for enclosure tuning? As a reference; horn HF, horn MID, 18" cone LF.
When the cabinet size approaches the Vas of the LF driver the alignment is considered a "infinite-baffle" design.
This would be a "sealed" cabinet the way I'm looking at it.
Let's see if anyone else chimes in on this topic.
Regards, Ron
Last edited by spkrman57; 05-25-2009 at 09:47 AM. Reason: added info
JBL Pro for home use!
As Ron said, fairly big.
But what is your intention? With a real open baffle you can get loose of enclosure resonances. But with a maintained enclosure you will miss this advantage. And you will presumably have an early bass roll off which must be compensated.
Which 18 inch speaker do you have in mind?
____________
Peter
Usually anything over a Qtc of 0.5 tends towards acoustic suspension and anything under tends towards infinite baffle.
Qt of a closed box
Here's a handy gadget to measure such things in real life:
http://www.woofertester.com/wt2product.htm
Cabinet large (>=Vas) is a pretty good guideline. Qts and Qtc are different. Qts is the driver in free air, the Q of the combined electrical and mechanical components of the driver at Fs (Qes and Qms). This determines (largely) what sort of box you want to use. Higher tends to need less help from a port, hence the preference for sealed. Lower tends towards vented, and very low belongs in a horn (for bass anyway).
Qtc is the Qts with the influence of the enclosure. When this is close to Qts, it's an infinite baffle enclosure.
Well... that might be some generallity found somewhere but I'm not real sure I'd want a 124/2203 or 136/2231 in a horn.Note that JBL puts low Qts midbass drivers in small sealed boxes.
The problem with these kinds of forum discussions is that they probably shouldn't exist (especially since they all go to Google now). Read the AES papers and myriad books instead. They do the subject a hell of a lot more justice than anything you'll find on some Internet forum. We went over this with Zilch early on and he dove right in as suggested.
More than the definition and relationship of speaker parameters by Claus Futtrup (former Dynaudio employee):
http://home1.stofanet.dk/cfuttrup/dpc/dpc.htm
____________
Peter
There are currently 2 users browsing this thread. (0 members and 2 guests)