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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => LAB Subwoofer Forum => Topic started by: Jacob Shaw on July 17, 2015, 07:48:00 pm

Title: 2242 response
Post by: Jacob Shaw on July 17, 2015, 07:48:00 pm
This isn't an acceptible response is it?  The jbl 2242 has a vas of 287L.  I modeled 2 of them in a 575l cabinet, and got this.  I played around with the volume and tuning and this is the best I could come up with, short of making the enclosure tiney at wich point it lacked extension.
Title: Re: 2242 response
Post by: David Morison on July 18, 2015, 10:05:55 am
This isn't an acceptible response is it?  The jbl 2242 has a vas of 287L.  I modeled 2 of them in a 575l cabinet, and got this.  I played around with the volume and tuning and this is the best I could come up with, short of making the enclosure tiney at wich point it lacked extension.

Seeing as you've cropped off both the Y axis and the box size & tuning, it's impossible to tell.
For all we know you've got it set to show 1dB per division, which wouldn't be too bad at all.
If you're at 10dB per division, that'd be a lot worse.

EDIT - on looking a bit closer, I think you're at 2dB/div with the level at 40-50Hz on 132dB, right? If so, that's certainly in the ballpark of what I'd expect from these drivers @ "program" power. Have you checked the Excursion at that level yet?

Title: Re: 2242 response
Post by: Lee Buckalew on July 18, 2015, 03:14:16 pm
This isn't an acceptible response is it?  The jbl 2242 has a vas of 287L.  I modeled 2 of them in a 575l cabinet, and got this.  I played around with the volume and tuning and this is the best I could come up with, short of making the enclosure tiney at wich point it lacked extension.

JBL recommends 1 driver per enclosure.  If making a dual they recommend that it be two, separated internal cavities.  They recommend a tuning of 40Hz.

Lee
Title: Re: 2242 response
Post by: Jacob Shaw on July 19, 2015, 01:34:48 am
Yes, the excursion plot is good.  I was just worried about the peak near 100hz. 
Title: Re: 2242 response
Post by: David Morison on July 19, 2015, 03:54:44 am
Yes, the excursion plot is good.  I was just worried about the peak near 100hz.

If you need to flatten that, a wide shallow PEQ set to maybe 300Hz would help quite easily.
It's not unusual for a box to have a response that's sightly skewed from flat (the STX828s uses these same drivers so you can get a bit of a comparison from that if you like) so things like out of band PEQ's are perfectly reasonable solutions.