15GTi LilWrecker Hornresp model... Is this right? - AVS Forum
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post #1 of 7 Old 01-31-2014, 07:43 PM - Thread Starter
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Howdy all. I'm trying to evaluate if my 15" JBL GTi subs are a good candidates for a LilWrecker cabinet. These are the T/S parameters for the JBL from JBL:

Fs: 25.2Hz
Re: 2.95 (coils in parallel)
Le: 1.06mH (@1kHz)
Sd: 780cm^2
BL: 15.39TM
Vas: 132.2L
Cms: 153.02
Mms: 260.67
Qms: 7.2
Qes: 0.51
Qts: 0.48
X-max: 20.32mm

Without further a do, screen SHOTS!

Gti Input Parameters
lilwreckerjbl15gtiinputparameters_zps9e9441d7.jpg

GTi SPL Response
lilwreckerjbl15gtisplresponse_zps16e84720.jpg

GTi / Kicker LilWrecker Comparison. GTi in black.
lilwreckerjbl15gtikickercompare_zps49af0b62.jpg

I am including the Input Parameter screen shot of the Kicker driver as provided from the LilWrecker thread and the resulting SPL Response graph for reference purposed. Read, just in case I goofed these up some how. :P

Kicker Input Parameters
lilwreckerkickerinputparameters_zpscf38e23e.jpg

Kicker SPL Response
lilwreckerkickersplresponse_zpsac23ba86.jpg

So, did I miss something here, or is the JBL that good? 0.o
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post #2 of 7 Old 01-31-2014, 09:27 PM
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I've looked at the JBLs.

As the JBL is a 4-ohm driver, the signal should be 2.00 volts for an apples to apples comparison. Technically, it should be even lower, because Re is below 3 ohms.

Most of that 4 dB difference is mostly due to the differences in driver impedance and signal level.

In my opinion, the GTi is too light on motor to be at its best in a tapped horn, and the Qes is a touch higher than I prefer.
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post #3 of 7 Old 01-31-2014, 10:41 PM
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if you want the 1 watt number, click on Eg and in the window enter 1 watt and for load impedance enter the driver's dc resistance (re), which in this case is 2.95.

this allows a more direct comparison of performance per watt. alternatively, you can wing it by using 2.83 for 8 ohm nominal drivers and 2.00 for 4 ohm nominal drivers, but in some cases you can miss by a couple db with that method.

Listen. It's All Good.
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post #4 of 7 Old 02-01-2014, 08:43 PM - Thread Starter
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Thanks gentlemen. I updated the input power of the JBL LilWrecker model, here is the input parameters screen shot.


Here is the updated SPL Response comparison screen. Gti in black.


Now that I've got a fair comparison, things don't look too bad for the JBL. I am a lil'bummed to hear lilmike's thoughts on the JBL in the LilWrecker. I decided to model my current JBL box, 4ft^3 tuned @ 28Hz for a little comparison. Here is the input parameter screen for the ported box.


Here is the SPL Response comparison screen. Gti LilWrecker in black.


Things look even better for the JBL in the LilWrecker cabinet compared to the ported box I've got now. So what do you all think? Yay, nay or do you have a better alternative?
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post #5 of 7 Old 02-02-2014, 08:37 AM
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If I had the GTis, I'd definitely use them, they're just not a driver I would recommend buying for this enclosure, as the Alpine Type S is a better fit (and cheaper). The mounting depth might be a bit too deep on the JBL too, once the thickness of the flange is taken into account.

Of course, this is all based on an analysis of the manufacturer-supplied T/S parameters, which may or may not have been filtered through the marketing department or altered as a result of changes in production. The CVX parameters I used are an average of the measured values of my drivers, and they matched reasonably well with the information I got from Kicker.
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post #6 of 7 Old 02-02-2014, 06:57 PM - Thread Starter
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Quote:
Originally Posted by lilmike View Post

If I had the GTis, I'd definitely use them, they're just not a driver I would recommend buying for this enclosure, as the Alpine Type S is a better fit (and cheaper). The mounting depth might be a bit too deep on the JBL too, once the thickness of the flange is taken into account.

Of course, this is all based on an analysis of the manufacturer-supplied T/S parameters, which may or may not have been filtered through the marketing department or altered as a result of changes in production. The CVX parameters I used are an average of the measured values of my drivers, and they matched reasonably well with the information I got from Kicker.

These are drivers i currently own, so im not exactly going out of my way here . biggrin.gif

I will give them a run through the ol DATS thingie and see how they compare to the supplied T/S Parameters. Till then, thanks for checking in and the advise. smile.gif
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post #7 of 7 Old 02-08-2014, 09:14 AM - Thread Starter
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I ran the JBLs through the DATS contraption and this what it spit out. A quick note here. For the Vas calculation I derived the piston diameter from the published Sd spec. I came up with 315mm.



For laughs here is a shot of my testing lab. :P



Some of the numbers varied a bit from the published parameters. Mind you, I've been running these subs since 2010, so I consider them fully broken in and them some. biggrin.gif Anyways, so I plugged the DATS derived parameters into the LilWrecker Hornresp Model to see what I'd get.

Here is the Input Parameters screen with the DATS T/S parameters.



Here is a comparison SPL Response between the published GTi params and the DATS calculated params. DATS GTi in black.



For added reference here is a SPL Response comparison between the Kicker LilWrecker and the DATS tested Gti LilWrecker. DATS GTi in black.



Well things aren't looking too promising for the Gti in a Lilwrecker. Maybe a Lilmike F20 is in order. smile.gif
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