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Need amp for JBL GTi MKII

post #1 of 68
1/24/13 at 12:49pm
Thread Starter 
I have built many subwoofer enlosures for cars, now I'm looking to build one for my home theater. I'm assuming it will outperform any mass marketed hometheater sub dollar for dollar; correct me if I'm wrong. I have decided to go with the 15" JBL GTi MKII after reading many great reviews on it. Now, I need an amp to power it. I would really like to go with a PA style amp as plate amps do not seem to offer the amount of power I'm looking for. There are a couple of issues I'm having while researching this. The subwoofer is a dual 6 ohm sub and I cannot find any PA amps that are 2 ohm stable bridged. I also do not want one channel to go unused. That seems wasteful. I plan on going ported as well. Do these PA amps have subsonic filters or should I just stick with a sealed enclosure and call it a day?

Thanks in advance.
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post #2 of 68
1/24/13 at 1:51pm
Thread Starter 
What are some common mistakes I should avoid when building this subwoofer?
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post #3 of 68
1/24/13 at 1:57pm
First off, welcome to the forum.

That sub is a wicked driver. I've owned a few in my vehicles and they are a great SQ/SQL sub. That being said, there are better options out there for HT use.
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post #4 of 68
1/24/13 at 2:06pm
Thread Starter 
Quote:
Originally Posted by bass addict View Post

First off, welcome to the forum.

That sub is a wicked driver. I've owned a few in my vehicles and they are a great SQ/SQL sub. That being said, there are better options out there for HT use.

Where would be a good place to research this stuff? Information is all over the place and I am having trouble putting all of it together to make a decision. I figured this would be a good place to start. What subwoofer/amp combos would you recommend? I'm most likely going to go with JBL Synthesis LS series speakers. The matching subwoofer is $1,000 and I'm pretty sure I could build something that more than out performs that for the price. I just need help getting started. I've been reading forums all day.
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post #5 of 68
1/24/13 at 2:12pm
The popular options as of late have been either SI 18's or Dayton 18's. You could pick up a pair of them in a dual opposed box hooked up to a Behringer EP4000 amplifier putting out 1900 watts, and absolutely trounce the commercial sub you're looking at. All for a total cost of around 800.00.

Do a search through this forum and you'll see quite a few builds utilizing these drivers. This is only one option, I'm sure others will chime in on a few more.
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post #6 of 68
1/24/13 at 2:40pm

The EP4000 can do 2 ohm stereo so you can wire up one driver per channel.

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post #7 of 68
1/24/13 at 3:04pm
Thread Starter 
Curious as to why everyone uses the EP 4000. I know they're cheap, but how do they compare to a Crown or QCS? If I'm using two drivers, I'd rather place them in different parts of the room rather than in the same enclosure. I would also like to keep the amp with the sub so I don't have long runs of thick speaker wire. I really like JBL products, that's why I want to stick with those speakers. They are a little more expensive but they have treated me good over the years. Cheaper than a W7 as well.
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post #8 of 68
1/24/13 at 3:09pm
Quote:
Originally Posted by j1gold16 View Post

Curious as to why everyone uses the EP 4000. I know they're cheap, but how do they compare to a Crown or QCS?

You mention a budget of around $1,000. The setup I proposed will get you there. Sure you can do a crown, and they are a little nicer; but I doubt you see any difference with this setup running one.
Quote:
If I'm using two drivers, I'd rather place them in different parts of the room rather than in the same enclosure. I would also like to keep the amp with the sub so I don't have long runs of thick speaker wire. I really like JBL products, that's why I want to stick with those speakers. They are a little more expensive but they have treated me good over the years. Cheaper than a W7 as well.

I agree with 2 separate drivers to combat room nodes. Once again, JBL's are great for a vehicle. If you are set on using them fine; but as mentioned earlier it's not the best option for a HT.
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post #9 of 68
1/24/13 at 3:34pm
I understand the desire for sticking with a specific brand you trust. I recall several builds on this forum back around 2011 using this JBL driver, many of the builds produced very good results. The JBL driver was used for sealed, dual opposed, and ported designed. Search the driver on this forum and you will find lots of builds to review.

Are there better drivers available? That depends on your specific requirements and application.
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post #10 of 68
1/24/13 at 4:24pm
one of the best 15" driver around. i use mine with a inuke 3000dsp
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post #11 of 68
1/24/13 at 9:49pm
Thread Starter 
Quote:
Originally Posted by bass addict View Post

You mention a budget of around $1,000. The setup I proposed will get you there. Sure you can do a crown, and they are a little nicer; but I doubt you see any difference with this setup running one.
I agree with 2 separate drivers to combat room nodes. Once again, JBL's are great for a vehicle. If you are set on using them fine; but as mentioned earlier it's not the best option for a HT.

Thanks for the advice. I have skimmed a few articles that said these subs sound good in a home theater setup and I am familiar with the brand. People often compare them to the W7 in car audio and the W7 is used in JL's home theater subwoofer line. What makes a subwoofer a home theater sub?
Quote:
Originally Posted by NWCgrad View Post

I understand the desire for sticking with a specific brand you trust. I recall several builds on this forum back around 2011 using this JBL driver, many of the builds produced very good results. The JBL driver was used for sealed, dual opposed, and ported designed. Search the driver on this forum and you will find lots of builds to review.

Are there better drivers available? That depends on your specific requirements and application.

Thank you for your input. I think that this driver will be better than the one used in the JBL Synthesis LS subwoofer and be able to holds it's own with many other subwoofers out there. I trust JBL and they have been around for years. They have the money to put into research and development. It may not be the very best but I think it's far from the worse.
Quote:
Originally Posted by datranz View Post

one of the best 15" driver around. i use mine with a inuke 3000dsp

Are you only using one channel of that amp or is it stable down to 3 ohms? I don't imagine you would run it at 12 ohms.
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post #12 of 68
1/24/13 at 11:55pm
Quote:
Originally Posted by datranz View Post

one of the best 15" driver around.

I'm with Datranz, it's an excellent subwoofer driver. Ignore all the naysayers. For great results you could try a Yamaha P7000S amp. Enough power and you will rarely if ever hear the fans come on under load. If fan noise is not an issue, try any of the known name amps delivering 750 - 1000 watts into 8 ohms
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post #13 of 68
1/25/13 at 12:13am
"The subwoofer is a dual 6 ohm sub and I cannot find any PA amps that are 2 ohm stable bridged."

voice coils in parallel (3 ohm mode) are really more like a normal 4 ohm load. the dc resistance is 2.95 according to jbl and somebody measured on at 3.17 ohms, which is actually higher than some nominal "4 ohm" subs.

parallel wiring to bridge connection that can handle 4 ohm nominal should be fine.
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post #14 of 68
1/25/13 at 1:39am
Quote:
Originally Posted by Antripodean View Post

I'm with Datranz, it's an excellent subwoofer driver. Ignore all the naysayers. For great results you could try a Yamaha P7000S amp. Enough power and you will rarely if ever hear the fans come on under load. If fan noise is not an issue, try any of the known name amps delivering 750 - 1000 watts into 8 ohms

I keep looking at the P series, they look great on paper and don't appear to be blatant ripoffs of other companies designs.
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post #15 of 68
1/25/13 at 1:45am
Quote:
Originally Posted by j1gold16 View Post


Thank you for your input. I think that this driver will be better than the one used in the JBL Synthesis LS subwoofer and be able to holds it's own with many other subwoofers out there. I trust JBL and they have been around for years. They have the money to put into research and development. It may not be the very best but I think it's far from the worse.

I don't have JBL sub drivers, but I love the 2226H drivers in my speakers.
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post #16 of 68
1/25/13 at 4:51am
Quote:
Originally Posted by NWCgrad View Post

I don't have JBL sub drivers, but I love the 2226H drivers in my speakers.

That 2226h is a great woofer, but, it will not work very well for a subwoofer. Not sure if that is what you were implying, if not, sorry smile.gif

The Dayton RSS460HO 18" inch or Stereo Integrity 18D2 or 18D4 would absolutely best that JBL Gti Mkii in terms of extension, and probably output as well. I don't know why the OP seems to be so stuck on JBL, but what I have found is that their consumer stuff is sub-par in the performance department compared to their pro stuff, which is excellent. That is just my opinion. If I were looking to purchase a new set up of theater speakers and a sub or two, I would build 3 of the Seos12 designs and 4 of the Seos10 designs as well as a pair of SI 18's or Dayton HO18's and call it a day. That would best just about every consumer level setup that cost under 5k+

just saying.
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post #17 of 68
1/25/13 at 4:58am
Find a 2242 and build one of these . http://www.jblsynthesis.com/Products/Details/110
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post #18 of 68
1/25/13 at 4:59am
Sorry for the confusion, I use the 2226Hs in my speakers. For subs I use 2 LAB12s (currently Uncle Sam has me living in Cambodia) and I have a Mael-X Gen II 18" sealed in storage back in the States. The 2226's don't really do bass.

I have a design for my Mael-X that will deliver >120 dB at 14 Hz (on paper). Will build when move back to the US this summer. Can't wait to get out of the constant heat and humidity!
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post #19 of 68
1/25/13 at 5:47am
Thread Starter 
Quote:
Originally Posted by Dezmond View Post

Find a 2242 and build one of these . http://www.jblsynthesis.com/Products/Details/110

Good idea but a little pricey.
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post #20 of 68
1/25/13 at 7:14am
Thread Starter 
Quote:
Originally Posted by datranz View Post

one of the best 15" driver around. i use mine with a inuke 3000dsp

So you have the Inuke 3000dsp running at 3 ohms bridged? How does the woofer handle that power? What size of box, what kind of box, hometheater or music?

And to those that are upset with me choosing this woofer, I just am comfortable with JBL and their products. If you really don't think that this will outperform a majority of premade/preconfigured setups, then I will choose one of the other recommended drivers. Thanks for all the input.
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post #21 of 68
1/25/13 at 8:01am
Don't run bridged. Get an amp with a bit of intelligence, wire each VC up to an amp channel and at the amp mirror the input to both outputs. You will be with in the amps envelope, you will be driving each VC with a channel and it will help a bit with thermal load.
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post #22 of 68
1/25/13 at 8:10am
Thread Starter 
Quote:
Originally Posted by Jinjuku View Post

Don't run bridged. Get an amp with a bit of intelligence, wire each VC up to an amp channel and at the amp mirror the input to both outputs. You will be with in the amps envelope, you will be driving each VC with a channel and it will help a bit with thermal load.

What's that technology called so I can search for it? Does Crown or QSC have a product that does that?
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post #23 of 68
1/25/13 at 8:17am
Quote:
Originally Posted by Jinjuku View Post

Don't run bridged. Get an amp with a bit of intelligence, wire each VC up to an amp channel and at the amp mirror the input to both outputs. You will be with in the amps envelope, you will be driving each VC with a channel and it will help a bit with thermal load.

wut no u dont want to do that at all.
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post #24 of 68
1/25/13 at 12:17pm
i dont run it bridge, one channel per sub.
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post #25 of 68
1/25/13 at 12:57pm
Thread Starter 
Ideally I would like to integrate the amp into the enclosure. Could I get a Crown XLS 2500 and run it bridged at 12 ohms? Would I need to have LFE inputs on both channels or would it recognize the signal from the one channel?
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post #26 of 68
1/25/13 at 6:29pm
Quote:
Originally Posted by j1gold16 View Post

What's that technology called so I can search for it? Does Crown or QSC have a product that does that?

Most of the amps with DSP can mirror (route) the input to both outs. Let me dig into my Behringer iNuke DSP and check.
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post #27 of 68
1/25/13 at 6:30pm
Quote:
Originally Posted by cookieattk View Post

wut no u dont want to do that at all.

Most eloquently stated.
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post #28 of 68
1/25/13 at 6:58pm
i believe it is called parallel mode. one input outputs to both channels.

not sure why you wouldn't just use the bridge connection. like i said, w15gti's "3 ohm" nominal rating is more like everybody else's "4 ohm".
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post #29 of 68
1/25/13 at 8:14pm

Seal 3.0cu box per channel of 3000dsp to raise the low end. Very nice comparable to av15h. Can't tell the difference between the two. I can use a little more power but I'm happy already. I wasn't happy until the 2nd sub.
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post #30 of 68
1/26/13 at 7:12am
Thread Starter 
Quote:
Originally Posted by datranz View Post


Seal 3.0cu box per channel of 3000dsp to raise the low end. Very nice comparable to av15h. Can't tell the difference between the two. I can use a little more power but I'm happy already. I wasn't happy until the 2nd sub.

Why were you not happy until the second sub? Why did you choose to go sealed?
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