JBL GTO1214 for PA/party use - diyAudio
Go Back   Home > Forums > Loudspeakers > Subwoofers

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 16th October 2013, 01:15 PM   #1
diyAudio Member
 
chris661's Avatar
 
Join Date: Feb 2008
Location: Sheffield
Blog Entries: 8
Default JBL GTO1214 for PA/party use

Hi chaps,

I have a pair of JBL GTO1214 drivers (4ohm each) that aren't currently in use.

I'm thinking of putting these into a cabinet for PA/party use: a similar idea to Art Welter's dual Lab12 ported design.

The way I see it, a pair of these drivers will have a cone area similar to that of an 18" driver. With 1/2" one-way travel, there should be some considerable output available.
That said, these are heavy cones (mms ~200g IIRC) so they'll need a considerable amount of power to boogie.

Because the cones are rather heavy, some force cancellation would be handy as this ought to stop the cabinet walking around. This pushed me toward the idea of a PPSL enclosure. Distortion is reduced by the opposite mounting of the drivers, and the drivers themselves are also out of the way of prying fingers, drinks, feet etc.
That said, the plenum adds a fair amount to the cabinet volume, so this might dissuade me yet: I'd like to keep this compact in order to keep transporting the thing nice and easy. One-man lifts only (though I can move two-way 2x15" cabs without much bother, so the weight won't be a huge issue).

The enclosure will be in the 80-120L range, probably ported tuned to the mid-low 30s. I'd be open to other design suggestions such as tapped horns, but I'm struggling to get a decent 35Hz TH with these drivers without going to ~150L, which is definitely bigger than I'd like to use.

Advise would be appreciated, even if its just "sell those drivers and get something worthwhile".

Cheers
Chris
  Reply With Quote
Old 16th October 2013, 03:52 PM   #2
GM is offline GM  United States
diyAudio Member
 
GM's Avatar
 
Join Date: Jun 2003
Location: Chamblee, Ga.
A ~100 L net Vb [including duct vent]/28-32 Hz Fb bi-pole reflex looks good, so converting it to a TQWT to deal with the long vent seems a good choice if there’s plenty of clean power on tap.

GM
__________________
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
  Reply With Quote
Old 16th October 2013, 04:09 PM   #3
diyAudio Member
 
chris661's Avatar
 
Join Date: Feb 2008
Location: Sheffield
Blog Entries: 8
Hi GM,

I was thinking of buying a 2nd hand Behringer EP1500 on eBay, and put the JBLs in parallel. Bench tests indicate it won't stand both channels driving 2ohm (the PSU current draw gets silly), but I'd expect it to be fine driving only one channel at 2ohm: the other channel is blown.

Here's a link to the power amp tests:
Measuring Amplifiers - Page 2

I'll have another look at TQWTs and see what can be done

Cheers
Chris
  Reply With Quote
Old 16th October 2013, 05:44 PM   #4
diyAudio Member
 
Join Date: Jan 2008
Quote:
Originally Posted by chris661 View Post
I was thinking of buying a 2nd hand Behringer EP1500 on eBay, and put the JBLs in parallel. Bench tests indicate it won't stand both channels driving 2ohm (the PSU current draw gets silly), but I'd expect it to be fine driving only one channel at 2ohm: the other channel is blown.
Chris,

The average power draw using sine waves is around 10 times (or more) what it will be playing music.

Have you tried modeling the JBL speakers in Hornresp using any of the usual TH enclosure specs?
For party/PA use the extra output per watt is a good thing.
  Reply With Quote
Old 16th October 2013, 11:03 PM   #5
diyAudio Member
 
bitSmasher's Avatar
 
Join Date: Jun 2012
Location: Sydney.Au
Quote:
Originally Posted by chris661 View Post
they'll need a considerable amount of power to boogie
Absolutely - I've been playing around with GTO driver numbers in WinISD and Hornresp, the response looks great but then you look at Max SPL and the power it takes to get there... it's not so great.
If you already own them, go ahead and build a reflex box to see what they do! Don't expect huge output for party use and I wouldn't run out to buy them for PA either, but they'd definitely make for a decent home theatre/music sub
  Reply With Quote
Old 17th October 2013, 01:24 AM   #6
diyAudio Member
 
Join Date: Nov 2007
Quote:
Originally Posted by chris661 View Post
Advise would be appreciated, even if its just "sell those drivers and get something worthwhile"
Well, seeing that option is already nixed, have you considered a 4th order BP design? You might get a few more dB out of them with something like that, at the expense of some low end which will likely not be missed anyway considering the planned use.
__________________
www.diysubwoofers.org
  Reply With Quote
Old 17th October 2013, 08:55 AM   #7
more10 is offline more10  Sweden
diyAudio Member
 
Join Date: Feb 2011
Location: Solna
Build your own 2x12" TH (The Kraken 212 TH)

Its 500 liters though.

Click the image to open in full size.
  Reply With Quote
Old 17th October 2013, 09:41 AM   #8
diyAudio Member
 
chris661's Avatar
 
Join Date: Feb 2008
Location: Sheffield
Blog Entries: 8
Yep, the Kraken is waaay too big, but the low end extension is handy.

Brian, I've never heard the term "nixed" before. Would you mind explaining?
I'll have a play on Hornresp to see if 4th order BP designs are worth a go. I must admit that I hadn't really considered them.

BitSmasher, I agree the sensitivity will be an issue. The other way of looking at it is that, with these drivers I'll get quite a lot of LF extension in a fairly small box. A powerful amplifier will be needed, but that'll be re-usable for bigger projects when I have more space to play with.
The drivers are quite hardy, though: I pushed a 600w amp to clipping, driving a pair of the drivers in a 35L sealed box, at 5Hz. They smelt warm, but still work fine. I expect with a bigger enclosure and a less demanding duty cycle, you could get away with 500w per driver.

Cheers all, looks like there's more simulation to be done.

Chris

PS - BitSmasher, I used a single 1214 in a 75L ported box with a big slot port tuned to 18Hz, then added eq to flatten the response down to Fb (like a Linkwitz Transform, but not quite). If you've got a couple of hundred watts to play with, its an impressive sub.

Last edited by chris661; 17th October 2013 at 09:45 AM.
  Reply With Quote
Old 17th October 2013, 05:52 PM   #9
GM is offline GM  United States
diyAudio Member
 
GM's Avatar
 
Join Date: Jun 2003
Location: Chamblee, Ga.
Google is your friend :
https://www.google.com/search?q=nixe...sm=93&ie=UTF-8

GM
__________________
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
  Reply With Quote
Old 27th October 2013, 06:17 PM   #10
diyAudio Member
 
chris661's Avatar
 
Join Date: Feb 2008
Location: Sheffield
Blog Entries: 8
Me again,

Dragging this back up as I definitely need more output from my subs: last night I blew my Tannoy T40 (pictures over on the PA forum) with a combination of ample amplifier ratings and mashing pop music into the compressor. In hindsight, the sub didn't stand much chance - compression is just as bad as clipping as the power delivery still increases as you bring the average level toward the peak. I'll avoid that in future - expensive mistake, too: those RCF drivers are 160 each.

I think I'll throw some ported boxes together for the JBLs - a pair of 50L cabs tuned to ~30Hz looks decent on the graphs, and would be a much easier lift than 100L and both drivers.

6th order bandpass looks reasonably promising, but you can get similar at the bottom end with a 20% smaller ported box (above the very bottom end, ported box wins 40-50Hz, but the BP wins 60-80Hz - I'd call it a draw). 4th order BP just doesn't get the sensitivity up enough, so I've ruled those out.

Chris
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
C/E/X PA Flat to 30 (FT30) PA TH Awesomeness CRESCENDO Subwoofers 762 17th January 2014 02:41 PM
Sale: JBL 16" K145, JBL 8" 2118, JBL 2404 HF, Fane ST-5022 (Edgarhorn), Klipsch K55V ZERO1 Swap Meet 3 3rd February 2013 11:03 PM
2 - JBL 123A-1 -- 12" woofers -- from JBL L88, but also L100 Jimmy154 Swap Meet 3 26th October 2012 07:13 PM
Vintage Peavey PA-120 Transistor PA amp ElectricMan Swap Meet 2 26th May 2010 05:22 PM
JBL PA Items for sale mixbob Swap Meet 1 28th November 2005 01:05 AM


New To Site? Need Help?

All times are GMT. The time now is 06:41 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2