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JBL JRX125s

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Strange Daze View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Strange Daze Quote  Post ReplyReply Direct Link To This Post Posted: 15 September 2008 at 7:43pm
Right....
so heres another query.
Im in the market for some subs to go underneath...
Any recommendations that are JBL branded??
:)
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DJ Nick View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DJ Nick Quote  Post ReplyReply Direct Link To This Post Posted: 16 September 2008 at 5:27am
Hi Strange Daze;)
 
 Mate i've got a couple of JRX125's with two Gsubs (twin 18 RCFp300's) as per this site plans. And they mate up really well. Probably close to an srx box if you compare with a jbl.
 Thes subs are 2k each. i run 2 of them of a crown xls5000 and they reek havok. The whole place shakes to the point weve had the cop station down the street complain they will shut us down if we dont turn it down. And i really have to comment on how tight they sound, not your typical vented boom box.. well designed ported box thanks to Rogs design work. If you want a good box to work underneath these i would recommend building the g sub.
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Strange Daze View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Strange Daze Quote  Post ReplyReply Direct Link To This Post Posted: 17 September 2008 at 3:17pm

Sounds like the Gsub may be the way to go....

Does a 125 REALLY keep up with 2k of Gsub tho.....or are you talking 2 x JRX125 per Gsub??

 

Cheers,

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DJ Nick View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DJ Nick Quote  Post ReplyReply Direct Link To This Post Posted: 18 September 2008 at 1:15am
Hi Daze,
 
 Mate i've got 1 pair of JRX 125's over one pair of G-subs.. thats two speakers only. They keep up. They are very sensitive, obvioulsy nowhere near the quality of a well designed MT102 or anything like that. the 15 in them tends to beam a bit and they can sound a a little harsh when your running about 500w into each box but they hold together. and they are pretty  loud. So yes they do keep up.. And i have to say ive been thinking of getting rid of the internal crosover and running the two fifteens in that box active over the same frequency range.. then they'lll be even louder, cause at the moment they are running through the passive crossover and actively crossed at 90 hz. which means the bottom woofer only works from 90 to around 150 if im not mistaken although this is just a guesss. they are a "quasi 3 -way " which means the lower woofer has the mids cut out of it, but they both produce the same bass spectrum. When running them as mid tops though, that lower 15 ich driver is barely working. So if i crossover full active running both 15's over 90 to 1.2k say they will be deadly sensitive. im thinking about it, but i would then have to upgrade the stinky comp in there to keep up with the mid woofers..more work....... and then ill start getting out the measurement tools.. again. ive only just packed everything up after my MT102 build, lol..still getting over that project. But they definately will sound cleaner if actively driven with a good comp. he he..
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Strange Daze View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Strange Daze Quote  Post ReplyReply Direct Link To This Post Posted: 18 September 2008 at 8:28am

Cheers for that....

So the concensus is to:
- Take out the passive X-Over.....
- Cross both 15s at the same frequency.....
- Upgrade the Comp driver....
- Build some GSubs.....
 
sounds like a new winter project for me....   :)
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DJ Nick View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DJ Nick Quote  Post ReplyReply Direct Link To This Post Posted: 18 September 2008 at 6:16pm
Spot on Daze!
 
 My only question now is finding a damn good comp that is a screw on 1" that will keep up with two fifteens, and safely crossover around 1.2k at 24db/oct. That will need some more homework. Ill keep you posted with anything i find might be capable of doing a good job. At this point the P.audio BDm 450s might be the go.. or eminence 2002s. not sure.. probably better options, ill have to loook a little deeper into this one... or do we just can the stock horn and replace with a bolt on flare? that might give us some more options, but the trouble is, theres not much room for a bigger horn in that box. hmmm


Edited by DJ Nick - 18 September 2008 at 6:19pm
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Deadbeat View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Deadbeat Quote  Post ReplyReply Direct Link To This Post Posted: 18 September 2008 at 6:43pm
JBL do a line of screw on comps (obviously).
So do BMS (4540ND).

Or you could get an adapter.
Away on extended leave.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote krazyneil Quote  Post ReplyReply Direct Link To This Post Posted: 18 September 2008 at 11:15pm
if your going the non budget route then get a s/h pair of jbl 2426 as they have screw fitting and will keep up with the 15's and crossover low enough
GOD TOLD ME TO DO IT !!!!!
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DJ Nick View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DJ Nick Quote  Post ReplyReply Direct Link To This Post Posted: 19 September 2008 at 3:33am
Thanks Neil, I will definately consider.. they look good.
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Strange Daze View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Strange Daze Quote  Post ReplyReply Direct Link To This Post Posted: 19 September 2008 at 1:45pm
Originally posted by DJ Nick DJ Nick wrote:

Ill keep you posted with anything i find might be capable of doing a good job.
 
 
Please do...
I have no more Cash at the moment...Until after Christmas, but then i'll be looking to replace the 4 horns, and get 4 x 18s to sit under the 4 x double 15s...   :)
 
 
...Gonna be a muchnicer rig than my old mish-mash pile of homebrew scoops of various descriptions and crappy built HDs....
(I may even consider building some nice HDs to go between the 18s and the double 15s.....).....add that bit of lowmid/kick that the jrxs seem to be short on. Dont know if its worth the effort tho, as the JRXs seemed fine in that respect with some EQing...what dya think, you ever heard HDs??
 
 
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ted01 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ted01 Quote  Post ReplyReply Direct Link To This Post Posted: 24 September 2008 at 7:54pm
hey gang,
 
I've got two of the JRX125's as well.  I plan to acquire two more of them in the future.  They will be used as the FOH speakers for mainly outdoor rock gigs.  I also have two Eminence Omega Pro 18C speakers (again, with two more in the future).  I could really use some advice on cabs for the 18C's.  I've been looking and looking and just can't make up my mind what I want to build.  I started considering front loaded ported cabs, but I am having a hard time with the compromise between low freq response and power handling.  To get really low freq response, I seem to have to sacrifice most of the power handling capabilities of the speakers.  To go the other way, I have to sacrifice the lows.  Dang it, I want BOTH!!!  So then I started to look at horn loaded subs.  They seem to be much more sensitive to the type of speaker loaded into them. 
 
So, here's my question...  Since the 125's go down pretty darn far, I'd want to drive the 18's from say 30Hz to maybe 100 or 125 Hz.  Anybody have any ideas on a good box design that would let me get into that freq range AND allow me to power the heck out of the Omega Pro 18C's?  (I mean heck, they're rated at 800 watts/1600 watts program)  I have a pair of QSC GX5 amps (700 wats into 4 ohms) and I'd like to use most of that power.  Looking at the Eminence site, they have a couple of front load designs, but jeez, at most I can use only 400 watts with an F3 of 54 Hz.  I want to go lower AND have more power handling.  Am I just being dumb?  Is this impossible?  No way to get 30 Hz out of these speakers and be able to shoot at least 500 watts at them? 
 
Thanks in advance for any help. 
 
Ted
 
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da_audio_don View Drop Down
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Post Options Post Options   Thanks (1) Thanks(1)   Quote da_audio_don Quote  Post ReplyReply Direct Link To This Post Posted: 28 September 2008 at 1:03am
Hey Ted,

            You won't be able to get 30Hz from that speaker and have it safely handle 500 watts. You are going to run out of excursion if you pump more than 400 watts into this driver if its  in a vented enclosure. It could bottom out, or you could end up putting a crease in the cones from exceeding the driver's xmax. I think this driver might work better in a folded horn enclosure such as scoops or the 186 horn. If you're looking for response down to the 30s, you're going to need a driver with a slightly higher Qts and more excursion capability (higher xmax). You might also want to look into tapped horns as well. Just my two cents.


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