Xmax lower than recommended recycling drivers

The Jack of All Trades pro-sound cabs.
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joblow88
Posts: 68
Joined: Sun Feb 13, 2022 8:18 pm

Xmax lower than recommended recycling drivers

#1 Post by joblow88 »

so my roomate have 2 JBL mrx525 kicking around. We already changed the tweeter for 2 asd1001. so i was thinking that i could reuse the parts to make a set of j115 or j215 since i'll only need a second pair of tweeter it would be a fairly cheep project. The only problem is that the JBL 265H woofer only has 2.5mm of xmax. Does it affect the sensitivity of the cab or just limit the max output i can get from it? i tough the best setup would be 4 j115 with two of them having compression driver for a portable all around setup. They mainly do punk metal and acoustic shows.
https://jblpro.com/zh/products/mrx525
https://www.cieri.net/Documenti/JBL/Thi ... bl-pro.htm

tallevan
Posts: 89
Joined: Sun Oct 20, 2019 12:15 pm
Location: London, England

Re: Xmax lower than recommended recycling drivers

#2 Post by tallevan »

Hi Job,

I recycled a non-recommended, out-of-spec woofer for a Jack 10 some time ago.
The thread is here: viewtopic.php?f=30&t=25520

It wasn't the same situation, it was just an experiment. But it worked out OK. Not as well as if I purchaced one of the recommended drivers.
In my case, the beautiful compression driver, horn and crossover overbalance the woofer, and the midrange predominates. The bass is improved by wall or corner loading, as Bill says. But the low xmax and other parameters of the non-recommended driver don't support a lot of bass in my case. But it's very loud.

Don't underestimate the cost of tweeters, wood and other materials for 4 J15s. That is a lot of commitment to try to save a bit of cash on woofers.
They would also be very, very large.

I might be more inclined to sell the JBL drivers on FleaBay, and build a couple of 12" OTOPs and a Titan sub.

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Bill Fitzmaurice
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Re: Xmax lower than recommended recycling drivers

#3 Post by Bill Fitzmaurice »

You don't mention subs, so I'm assuming you plan to run without them. With at least 5mm xmax that's feasible, but with 2.5mm xmax it's not. You'd be displacement limited to 20 watts each.

joblow88
Posts: 68
Joined: Sun Feb 13, 2022 8:18 pm

Re: Xmax lower than recommended recycling drivers

#4 Post by joblow88 »

Bill Fitzmaurice wrote: Tue Apr 19, 2022 7:12 am You don't mention subs, so I'm assuming you plan to run without them. With at least 5mm xmax that's feasible, but with 2.5mm xmax it's not. You'd be displacement limited to 20 watts each.
Well we were thinking of making t39 and sharing them. There would definitely be moment without sub but we would highpass the amp at 50hz. But for now they are kinda happy with the vented box they have and the sound they produce but i thought maybe in a jack enclosure they would sound better. So would a jack 15 make the driver sound better than the original box or not at all?

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Bill Fitzmaurice
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Re: Xmax lower than recommended recycling drivers

#5 Post by Bill Fitzmaurice »

The Jack might make them work better, but if you use a proper driver you'll get the same or better results from just two cabs. Also, the T39 isn't the best match for the J15, the T48 is. If all you need for the lows is T39 then J15 is more top than you should be using. IMO you should examine your actual requirements and choose the rig accordingly, and not make bad decisions based on trying to recycle old drivers that aren't worth the effort.

joblow88
Posts: 68
Joined: Sun Feb 13, 2022 8:18 pm

Re: Xmax lower than recommended recycling drivers

#6 Post by joblow88 »

ok sounds good. thank every body for the quick answers

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