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Need amp for JBL GTi MKII - Page 2

post #31 of 68
1/26/13 at 12:48pm
I toy with a few different 15s and the jbl and the ae were the top. I ran into all kinds of issues from over powering a single sub, to not hp sub, to null problems, placement problems. Once I got a second sub, all the problem went away.
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post #32 of 68
1/27/13 at 6:22am
Quote:
Originally Posted by LTD02 View Post

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".

You supposedly get better thermal performance. Whether or not you can hear it is another matter. Six one way, half dozen the other. I was just throwing out that configuration to ease the OP's mind about 3 ohm VCs'
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post #33 of 68
1/27/13 at 8:40am
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.

That's pretty high praise. For the AV15h, not the W15GTi. smile.gif
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post #34 of 68
1/27/13 at 7:38pm
Thread Starter 
I just got a great deal on two JBL W15GTI MKII's. $350 a piece brand new. I'm going to get a Crown XLS 2500 and a miniDSP as well. Do you think these will work well together. If there is a better amp and/or DSP, let me know. Now, I need to determine whether to go ported or sealed. Movies/Music listening is 50/50. I'm not concerned about how loud it can get because 2 15's should be louder than the 1 12" ported JBL/400watts. I want a flat response as low as I can go. I've had bad luck with small sealed enclosures in car audio; lacked low end but very musical in the upper range. I'm pretty happy with the ported JBL I have now. Size is only a moderate concern. Hoping a large sealed will yield great results, but I can also go ported. WinISD recommends 9.66 ft^3 tuned to 20 hz ported and 4.93 ft^3 sealed. Planning on doing two separate enclosures. I've looked through a lot of the subwoofer projects on here, but can't seem to come to a conclusion on what's best for my situation. If I do go ported, I will use a slot port. Any material difference between a slot port and a round port? I know I have a lot of questions but I want to do this right the first time so if there is anything I need to avoid, it'd be nice to know.

Thanks!
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post #35 of 68
1/27/13 at 7:45pm
sealed/ported kind of depends on the size of your room.

if you have a medium or small room, it will pick up some significant gain below about 30hz.

if you have a largish room, it might not start kicking in much gain until the teens hz.

you can also push the tuning frequency lower on the ported if you like. 16hz would be a good one if you are not trying to maximize spl. that is about the bottom note on the largest pipe organs and there are many movie effects that low (and lower).
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post #36 of 68
1/27/13 at 7:49pm
If you order a mini dsp, I'd go ahead and grab the mic from them as well. Also, familiarize yourself with REW. Great tuning software that will integrate well with the mini.

Did you compare excursion and SPL in Isd with your box size and amplification? That will be very telling on how they will compare.

Edit: I agree with LTD on the room gain, but I have seen some disappointing numbers compared to models when in real world listening. I'd consider room gain as an added bonus, but wouldn't rely on it IMO.
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post #37 of 68
1/27/13 at 9:09pm
Thread Starter 
So the consensus is to go ported and tune it to 16 hz? I'll post pics of the build.
Edited by j1gold16 - 1/27/13 at 10:15pm
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post #38 of 68
1/27/13 at 9:36pm
How big is the room?
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post #39 of 68
1/27/13 at 9:48pm
Quote:
Originally Posted by j1gold16 View Post

So the consensus is to go ported and tune it to 16 hz? I'll post picks of the build.

Well I see you are easily influenced. You went from wanting to learn as much as you can to running with the first recommendation that comes your way as the "consensus", and moving on to the build. While LTD has a lot of valuable information, unless you count all the voices in his head; I'd hardly say he's the consensus. tongue.gif
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post #40 of 68
1/27/13 at 10:04pm
Thread Starter 
My room is 20' x 40' with a 10' ceiling. I'm open to more opinions if you do not think low tuning will suit me well.
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post #41 of 68
1/27/13 at 11:28pm
that is a pretty large room. ported will provide much more spl in the 16-30hz region than a sealed in your room.

a tuning of anywhere from 15-20hz will be fine. the higher tune gives a couple db more spl in the low 20's. the lower tune of course gives more extension. as for which is best, that would be a personal preference. i think you will be happy with anything in that range.
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post #42 of 68
1/28/13 at 6:05am
Thread Starter 
Quote:
Originally Posted by LTD02 View Post

that is a pretty large room. ported will provide much more spl in the 16-30hz region than a sealed in your room.

a tuning of anywhere from 15-20hz will be fine. the higher tune gives a couple db more spl in the low 20's. the lower tune of course gives more extension. as for which is best, that would be a personal preference. i think you will be happy with anything in that range.

Thank you. Do you think WinISD recommendation of 9.6 ft^3 would be appropriate? What would the effect be if I tune it that low, then put it in a smaller room? I'm guessing I would have to turn the EQ down in the lower regions. Also is there anything wrong with choosing a slot port rather than circle ports?
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post #43 of 68
1/28/13 at 10:03am
"Do you think WinISD recommendation of 9.6 ft^3 would be appropriate? "

yeah, ~8-12 cubic feet is good for anything in the 15-20hz tuning range with that driver. 9.6 works just fine.

"What would the effect be if I tune it that low, then put it in a smaller room? I'm guessing I would have to turn the EQ down in the lower regions."

maybe a little, but that is what would be called a "high class problem" to have. :-)

"Also is there anything wrong with choosing a slot port rather than circle ports?"

sized appropriately and employing roundovers, both will perform well.

here is a decent primer on porting/flaring: http://www.subwoofer-builder.com/porting/index.htm
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post #44 of 68
1/28/13 at 9:09pm
Thread Starter 
I'm looking at the 6" precision port found at parts express.

http://www.parts-express.com/pe/showdetl.cfm?partnumber=268-354

It only is 17" long. I need a longer tube. Would regular pvc pipe work? I contacted the manufacturer but I have not received a response yet.

Thanks.
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post #45 of 68
1/28/13 at 10:44pm

PVC, sonotube, or a slot port would work.

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post #46 of 68
1/29/13 at 4:24am
the suggestion for sonotube is a good one. it is used as a cardboard tube form for concrete. it is available in the area where they sell concrete in your local home depot type stores. it is available in many different diameters and up to several feet long. it is also relatively inexpensive.
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post #47 of 68
1/29/13 at 7:06am
Thread Starter 
Quote:
Originally Posted by LTD02 View Post

the suggestion for sonotube is a good one. it is used as a cardboard tube form for concrete. it is available in the area where they sell concrete in your local home depot type stores. it is available in many different diameters and up to several feet long. it is also relatively inexpensive.

I'm not really into sonotube subwoofer designs. I like the conventional cube. I plan on adding a maple veneer to it to make it look pretty. I've laid out the design last night. 30" H x 30" D x 20" W, with double layer front and rear panels. 1 vertical brace in the middle. 6" port out the back, 20" in length. Nickel binding posts from Parts Express. Do I need feet for the enclosure? If so, what do you recommend?
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post #48 of 68
1/29/13 at 12:03pm

I was suggesting sonotube as the port, I believe the smallest diameter they come in is 6". I would get feet, you don't want this thing moving around. Spikes for carpet or rubber for wood flooring.

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post #49 of 68
1/29/13 at 2:45pm
Thread Starter 
Quote:
Originally Posted by Mrkazador View Post

I was suggesting sonotube as the port, I believe the smallest diameter they come in is 6". I would get feet, you don't want this thing moving around. Spikes for carpet or rubber for wood flooring.

Thank you. Do subwoofers really move around?
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post #50 of 68
1/29/13 at 3:19pm

Depends on a lot of things I suppose... Weight, driver excursion, finish, carpet

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post #51 of 68
1/29/13 at 3:50pm
"I was suggesting sonotube as the port..."

I was too.
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post #52 of 68
2/1/13 at 10:24pm
Thread Starter 
I used WinISD and came up with two possible designs. Can't determine which would be better. 2 - 4" ports or 1 - 6" port. 2- 4" ports show a higher SPL and gradual drop off and lower port velocity. 1 - 6" port is a flatter response and lower spl, drops off at 20 hz. I think two 4" ports is the way to go as room gain will make up for frequencies below 40 Hz (where it starts dropping off). I will be using precision ports from parts express. Thoughts?
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post #53 of 68
2/2/13 at 7:29am
either will work fine. by changing the length, you can tune the enclosure similarly with either one.

iirc, you have a 10 cubic footer tuned to 16hz. that would use either one 6" diameter port that is 25.25" long or two 4" diameter ports that are 23.7" long.

you can monkey around in winisd and see that the frequency response with either port setup will be the same.
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post #54 of 68
3/9/13 at 12:25pm
Thread Starter 
I've decided to go with a sealed design. 4.6 ft^3 using 1" MDF. Each woofer will have it's own separate enclosure and so I can place them in different parts of the room. I will wrap the enclosures in a cherry veneer. I purchased some satin nickel floor spikes and binding posts from Parts Express. I will line the inside of the enclosure with eggcrate foam purchased from foambymail.com (a lot cheaper than Parts Express).

I still have to purchase an amp and an EQ. I really like the Crown XLS2500 for the amp. For the EQ, I am undecided and need help. I've read some bad things about the miniDSP. Are there any other EQs/processors that you would recommend. Perhaps the Velodyne SMS-1, though I heard that you can't tune each sub independently and it's really expensive. Are there any good plate amps that have EQ built in?
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post #55 of 68
3/9/13 at 5:13pm
Since u r doing seal, I highly recommend 6000dsp.
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post #56 of 68
3/9/13 at 5:51pm
Thread Starter 
Quote:
Originally Posted by datranz View Post

Since u r doing seal, I highly recommend 6000dsp.

I like the DSP feature built in, but to be honest, I'm not a fan of Behringer. In reading their reviews, they don't seem to be the most reliable brand. I just read up on the QSC 4050HD. I'm strongly considering this, though it is more than double the Crown XLS 2500. :/ So many choices...
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post #57 of 68
3/9/13 at 6:07pm
Quote:
Originally Posted by j1gold16 View Post

I like the DSP feature built in, but to be honest, I'm not a fan of Behringer. In reading their reviews, they don't seem to be the most reliable brand. I just read up on the QSC 4050HD. I'm strongly considering this, though it is more than double the Crown XLS 2500. :/ So many choices...

The cv-5000 is still the better buy right now.
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post #58 of 68
3/9/13 at 6:48pm
Thread Starter 
Quote:
Originally Posted by Dezmond View Post

The cv-5000 is still the better buy right now.

I don't think these subwoofers could handle that much power. It's a nice amp and all but the high pass filter would need to be set to 35 Hz according to WinISD to keep excursion within the limits of the sub. I don't really want to run a dedicated outlet to run this amp either.
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post #59 of 68
3/9/13 at 9:32pm
the 2500 xls puts 775 watts into a nominal 4 ohm load (which is pretty much what the w15gti is in reality) each channel.

in the 4.6 cubic foot enclosures, that is sufficient to get to xmax at 30hz, so the power is fine.

behringer fbq1000 has lots of peq for $150.
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post #60 of 68
3/11/13 at 11:30am
Quote:
Originally Posted by j1gold16 View Post

I cannot find any PA amps that are 2 ohm stable bridged.

The Crown iTech's are dual 1-ohm stable, that's how I power my stuff (stereo 1-ohm). Been running like that for almost a year now, no problems.
But the iTech's don't like being bridged at any ohmage IMO, best to run it stereo 3-ohm; it will put 8000watts into the driver in that mode; which is enough power to cook the subwoofer on-demand.
(You could even hook two of them up stereo 1.5-ohm if you wanted, ~4kW per sub.)

This is an 8000 doing stereo 1-ohm, (the other sub on the other channel is doing the same excursion.)
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