JBL gto1202D for HT sub

[Buzzy]

Hi ! I was thinking of building a subwoofer based on this JBL gto 1202d driver. Unfortunately no one has built any with this driver. I dunno if i should go sealed with linkwitz or ported. I can accept a box size of 80L to 100L. When i modeled a sealed sub in winisd, it has little bass output below 25Hz. If i were to use linkwitz may i know how much of amp power i would need for boosting gains by 6dB ? And modelling using linkwitz circuit makes the driver hit excursion sooner at around 50Hz. If it is going to require crazy amounts of power, i might just settle for ported.

[Petriej]

From what little experimentation I have done on winisd, it would seem that below 30Hz can be tough for any sealed enclosure. The use of a port will give you a nice boost for much more below that. However, just remember your size constraints

[Foxx510]

I'm building two small sealed boxes using very similar JBL car subwoofers. I'll be using a linkwitz transform. I'm using two subs so they won't be working so hard, one would probably be struggling in a sealed box to obtain sufficient output.

[BHTX]

Any ideas for the best way to model an LT for sealed sub(s), as Buzzy mentioned? I'll be building this type of setup for strictly under 35-40Hz with 4 high excursion 15's, starting some time at the beginning of next month (hopefully). And as far as the linkwitz transform itself..any suggestions?

[Foxx510]

This page explains it well - http://sound.westhost.com/linkwitz-transform.htm

[BHTX]

Ah..thanks for the link. Forgot about that site. It's been a while, I needed a big memory refresher. I also spent a while messing with the XLS file.

On the other hand, check THIS out:
http://www.pvconsultants.com/audio/eq/linktran.htm

..Seems to be exactly what I'm looking for, although I'm not completely positive about that, since I just started entering parameters and everything. I'll keep messing with it and see how it goes..

[BHTX]

Ok well, that XLS isn't working for me..

I entered all the variable parameters, including amplifier info, etc... and noticed that nothing is showing up on any of the graphs. So I thought maybe I was missing something, and started clicking the buttons on the right hand side, and that's when I realized that I'd get an error message regarding a non-existant script every time I attempted to do anything. Jeez, that figures. So, that was a useless waste of time. Most of all, it got my hopes up, only to disappoint me. Sure seemed nice though.

Anyway, I'm looking at the Marchand WM8 BASSIS right now, and it sure seems like something I'd be interested in using. BUT, it only has RCA's for inputs and outputs, and I need balanced XLR to connect between the Denon Pro DN-A7100 and Mackie FR-2500 amp.

So, that sucks. If I don't get enough responses here, perhaps I'll start a new thread soon, in hopes of getting some suggestions for alternatives regarding a nice LT with XLR connections.

If you haven't noticed, I have no experience with DIYing with electronic components. So, building a linkwitz transform circuit is out of the question for me, regardless of how simple it might be. And besides, I want to have the ability to experiment with settings, and change them any time I want.

Oh and... 19" rack-mount would certainly be nice, since the rest of my equipment will be that way.

Any suggestions??

[Amit_112dB]

hi, nice choise i must say 93dB means its gonna be loud boom for sure, we dont have it in India yet other wise i would have used this 1 only
at JBL US web site they have all the details of this woofer, all T/S parameters, they have also shown designs to make a ported (around 30litres) and ported 50 litres, i ran lots n lots on winISD on this woofer.. this is what i concluded
this has a very high Vas
this woofer is designed for sealed enclosure use, if u use it for ported u'll get a large but not impossible port length
if u use this woofer for ported mode JBL ported design in this woofer manual gives port freq as 35Hz at 50litres , BUT when i ran my WinISD i was gettin quite diffrent results.......
in winISD i got sealed 80litres as compared to JBL which said 30 litres, JBL got 45HZ 3db, i got 35 in winisd
ported model was 20Hz port tuned, 18hz lower 3db which is OK as volume is 166 litres
my suggestion is reduce the volume to 100 litres and increase port freq to 23hz, 8.2cm dia *23.4cm port length, u get -3db as 23Hz, which is very-very nice
BUT THERE IS AN ISSUE WINISD is not giving the vent mach, it just sayz Qes/Pe, check the vent mach this woofer that u have, winisd is not at all giving vent mach for this woofer at all.......

Hope any of this is useful to u....

all calculation were for the 4ohm version of the woofer that u have gto 1204 DVC,

[Buzzy]

What kind of power would i need if i am to use linkwitz circuit ?

I tried with signal input power of 100W without LT and excursion was fine. However when i tried LT with 6dB gain excursion goes haywire.

[Foxx510]

Hopefully in use the Xmax issue won't be too much of a problem. Here is another website with some useful experiences of using the LT circuit
http://www.halfgaar.net/elf-subwoofer