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Author Topic: RIP JBL SRX  (Read 4766 times)

Ivan Beaver

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Re: RIP JBL SRX
« Reply #10 on: January 30, 2013, 06:48:22 pm »


Put that in the same catagory as "this cabinet get's to 139db, and this one get's to 142db. Which cabinet is better."
Or even worse-"Why does the one that only goes to 139 seem louder".

DUH-Maybe the way it is rated-and at what freq.

Simple single numbers usually don't mean much.  you HAVE to look at bit closer to get the REAL story.
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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

Jim McKeveny

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Re: RIP JBL SRX
« Reply #11 on: January 31, 2013, 07:04:30 am »

1m/1m across a near-identical passband.

I realize there are lots of  cabinet, LS & T/S parameters that do not make any spec sheet, but this in particular seems odd.
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Art Welter

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JBL SRX sensitivity differences
« Reply #12 on: January 31, 2013, 10:00:19 am »

1m/1m across a near-identical passband.

I realize there are lots of  cabinet, LS & T/S parameters that do not make any spec sheet, but this in particular seems odd.
Jim,

A picture is worth a thousand words, post up the charts of each "near-identical passband" and cabinet dimensions so we can see what you find odd.

Art
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Jim McKeveny

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Re: JBL SRX sensitivity differences
« Reply #13 on: February 01, 2013, 07:09:26 am »

www.jblpro.com/pages/pub/components/2226.pdf

www.jblpro.com/backoffice/productattachments/jbl_stx835.v1.pdf

1w/1m passband on the standalone cone is 100-500 hz.

Cannot find test LF starting point on the 2 x enclosure, but it tops out at 250hz.

I was kind of hoping  someone from the factory would weigh in.

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Ivan Beaver

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Re: JBL SRX sensitivity differences
« Reply #14 on: February 01, 2013, 07:26:57 am »

www.jblpro.com/pages/pub/components/2226.pdf

www.jblpro.com/backoffice/productattachments/jbl_stx835.v1.pdf

1w/1m passband on the standalone cone is 100-500 hz.

Cannot find test LF starting point on the 2 x enclosure, but it tops out at 250hz.

I was kind of hoping  someone from the factory would weigh in.
The problem with simply having a "0" point on a graph is that you don't know what SPL that 0 is referring to..

It could be anything, and maybe all they are trying to show is the deviation in amplitude response-not an absolute reference.

How you perceive the graph and other associated numbers in the spec sheet may not how they intended.

Unless you have graphs that are measured in close to the same way (distance-input level etc) it can be hard to say they are "the same".
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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

TJ (Tom) Cornish

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Re: JBL SRX sensitivity differences
« Reply #15 on: February 01, 2013, 09:15:56 am »

The problem with simply having a "0" point on a graph is that you don't know what SPL that 0 is referring to..

It could be anything, and maybe all they are trying to show is the deviation in amplitude response-not an absolute reference.

How you perceive the graph and other associated numbers in the spec sheet may not how they intended.

Unless you have graphs that are measured in close to the same way (distance-input level etc) it can be hard to say they are "the same".
Thought this was relevant here. "On paper" the new STX subs are a disappointment - heavier, higher operating frequency range, etc.  Digging in a little farther into the charts, it appears the STX subs aren't a step backwards, and if the graphs are to be believed, have more LF extension than SRX did.

My methodology for these (excluding the Fulcrum subs) was to take the 1/2 space peak number, find the highest point of the published curve, and subtract from there at each of the data points I was interested in.  For the Fulcrum subs, I used the "Equalized Maximum" and equalized curves.

Usual disclaimers apply - spec sheets lie, different measurement techniques, probably errors either on the spec sheets or in my copying, etc.  Please feel to correct this if you have better info than what I've found/calculated.
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Jim McKeveny

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Re: JBL SRX sensitivity differences
« Reply #16 on: February 01, 2013, 10:25:11 am »

We've moved from bassrange 15's to subs.

"First watt" (1w/1m) subwoofer measurements can paint as an inaccurate sonic picture as "calculated maximum SPL" ratings w/o charting where the device runs out of xmax gas or the onset of power compression.

Returning to my original posit (and hopefully someone within JBL can reply) it seems prima facie odd that a doubling of the the components results in a reduced a sensitivity rating, OR, what are the in-house sensitivity rating protocol differences that produce this result?

Loudspeakers are quite a stew, aren't they?

Interesting to me is that JBL has seen fit to employ the 20+ year old 2226's in current & competitive designs. I've long been a fan, and there are dozens of boxes I built in the 1990's still performing respectably and earning $ for their owners, but 2 decades is quite a stretch.
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Art Welter

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Re: JBL SRX sensitivity differences
« Reply #17 on: February 01, 2013, 04:19:43 pm »

Returning to my original posit (and hopefully someone within JBL can reply) it seems prima facie odd that a doubling of the the components results in a reduced a sensitivity rating, OR, what are the in-house sensitivity rating protocol differences that produce this result?
Jim,
There seems to be a discrepancy of about 1.5 dB from the STX 835 spec sheet's 96 dB "passive mode" sensitivity compared to the FR chart, which looks to be more like 97.5 dB in free field.
Since the cabinet is designed to be flown, it shows measurement in both free field and half space.
The half space measurement shows 100 dB sensitivity at 50 Hz, rising to 104 dB at 70 Hz.
Using the 2226 spec sheet, we can interpolate from the 60 watt chart that the "0" line on the frequency response curve of a 5 cubic foot vented cabinet is 97 dB 1 watt one meter half space,  about 96 dB at 50 Hz.
The STX 835 (probably about 4 cubic foot net per driver) is as much as 8 dB more sensitive than the 5 foot vented cabinet, but rolls off at about 12 dB per octave from 70 Hz, at 40 Hz the two boxes are about the same sensitivity.
Classic illustration of Hoffmann's Iron Law, low, loud, or small-pick two.
Also an illustration that using a single sensitivity figure is useless, you need to look at the FR graph to determine where the sensitivity is derived.
Anyway, thanks for the links, this is the first time I ever saw JBL underate (even if only by 1.5 dB) sensitivity on one of their cabinets.

Art
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