what goes wrong with the GTI subwoofers ?

Hey guys,

i finally own a JBL GTI MKII 12"

BUT : something has gone wrong with it. :mad:
The first enclosure was a 2.25 cuft ported that sounded
ok till it blew apart, that's when the the GTI started to make
mechanical " bottoming " sounds.

So we tried it in free air before building a new sealed enclosure
just to test it, it seemed fine running in the open so a sealed
1.2 cuft box was built.
It sounds amazing until a certain power level is reached and the awful
noise rears it's ugly head again which has me turning down
the bass control instantly because it is a LOUD scary " WHACK ".
The amp is an Audison UNO and the gti runs at three ohms, so
it is seeing approx one thousand watts.

Im hoping someone out there has experience with the GTI's and
can point me in the direction of what to inspect :
- a separated spider ?
- voice coil former separated from spider ?
- something else ?

i just hope that this amazing woofer is saveable.....

thanks !

Lurch,

New sub time

AAAAAUUUURGH !
NOOOO !:cry:

Lurch,

A subsonic filter with a vented/ported box. But the big boys just let it unload "rumblin" , then you buy another / another /
Rinse and repeat

This turned out to be a bad power wire issue.
The wire i was using just wasn't sufficient.
Today i installed a dedicated 2ga. cable and the problem has " mostly " disappeared.
The crapping sound is only there at very high SPL now.
EVERYTHING sounds better.
The next step is to inspect all the associated grounds, if that doesn't completely clear it up
I will reduce the box volume ( 1cuft is recommended by the manual, the current box is about 1.2 ).

This GTI is just fine, my own stupidity on the other hand ......

Glad you got it mostly straightened out. The GTI is an amazing sub in all variations. Sounds like your amp wasn't happy and still isn't as happy as it should be.

Hi Hillbilly,

i'll update with what i find with the ground, i used the closest seat bolt and im always in a hurry, i seem to remember
sanding the paint off the seat rail but who knows ....
i also wonder if I should be using a different bolt, something more conductive.
Once i get the dremmel set up with a sanding disc the bolt will come out, the seat rail will get a PROPER sanding and
i'll clean up the bolt threads + the hole threads, pretty sure this will clear the situation up for good.
This poor Audison must have been going through hell in the last few years but it never complained, never got warm,
never missed a beat. Gotta Wonder how much distortion it was producing though.
( it was driving a DC Audio level three in a ported box previously and got LOUD )


BTW.... Love your sig, funny as hell ....

If sanding around the bolt doesn't work you might need to find a good area to run a bolt straight through the floor. That's what I always did when my battery was under the hood and never had an issue.

And thanks for the compliment on the siggy. Spanish Harlem is an old SQ comp song that has been so overplayed it's ridiculous and it's to test sub to midbass transition. Used to joke that playing it in my truck would cause the seat to eject the listener out of there.

JL Audio has a great lug I've used on many occasions for just this purpose.

Attachment 6538

^^^ nice lug ! :D:D

Anyways..... Finally got around to ground inspection / upgrade, i had actually done a pretty good job the first time
( to my astonishment), paint was sanded off, bolt head & washer clean.
I dremmeled the surface this time with a sanding disc, cleaned up the bolt threads on a wire wheel, pull tested the
eyelet and reset. The ground cannot be better now.
Did it help ?
maybe by a very small percentage.

This very could be the UNO crapping out, it is rated for 700 watts at 4ohm, the GTI is 3ohm, maybe it's time to
find a class D that is capable, unfortunately it would require a large class D at that impedance.
The voltage is good and steady, never goes below 13.2 at idle with the music cranked.

So now a " spec " box will be built @ 1 cuft, this could help, but really, how much ? ( present box = 1.3-ish ).
It's a minor annoyance now, not like it was at the beginning of this thread, i could live with it.

Another update :

i swapped out the uno for a less powerful Rockford ( punch 1000x2 ) and the issue completely disappeared.
I now have my upper bass frequencies back, it sounds much better and 80hz is solid again.
On the hunt now for a more powerful amp than the little RF ( heating up, doesn't like being bridged @ 3 ohm ).

Does anyone know what would cause an amp to fail in the upper bass registers ?
Always in the 80hz area, if 80 was eq'd almost completely down and the nearest bands turned down a few
db's the issue mostly vanished. The uno failed only in this area. It was fine before the box fell apart.
I removed the lid hoping to find a blown cap or diode or ? , but all looks well. Maybe an IC somewhere failed ?

happy to finally have this diagnosed, it was irritating as hell.

Quote:

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Originally Posted by Lurch

Hey guys,

i finally own a JBL GTI MKII 12"
ohhhhh noooooooooooooo
BUT : something has gone wrong with it. :pout:
The first enclosure was a 2.25 cuft ported that sounded
ok till it blew apart, that's when the the GTI started to make
mechanical " bottoming " sounds.

So we tried it in free air before building a new sealed enclosure
just to test it, it seemed fine running in the open so a sealed
1.2 cuft box was built.
It sounds amazing until a certain power level is reached and the awful
noise rears it's ugly head again which has me turning down
the bass control instantly because it is a LOUD scary " WHACK ".
The amp is an Audison UNO and the gti runs at three ohms, so
it is seeing approx one thousand watts.

Im hoping someone out there has experience with the GTI's and
can point me in the direction of what to inspect :
- a separated spider Bluestacks Kodi Lucky Patcher ?
- voice coil former separated from spider ?
- something else ?

i just hope that this amazing woofer is saveable.....

thanks !

---

ohhhhh noooooo :pout:

Quote:

---

Originally Posted by Lurch

Hey guys,

i finally own a JBL GTI MKII 12"

BUT : something has gone wrong with it. :mad:
The first enclosure was a 2.25 cuft ported that sounded
ok till it blew apart, that's when the the GTI started to make
mechanical " bottoming " sounds.

So we tried it in free air before building a new sealed enclosure
just to test it, it seemed fine running in the open so a sealed
1.2 cuft box was built.
It sounds amazing until a certain power level is reached and the awful
noise rears it's ugly head again which has me turning down
the bass control instantly because it is a LOUD scary " WHACK ".
The amp is an Audison UNO and the gti runs at three ohms, so
it is seeing approx one thousand watts.

Im hoping someone out there has experience with the GTI's and
can point me in the direction of what to inspect :
- a separated spider ?
- voice coil former separated from spider ?
- something else ?

i just hope that this amazing woofer is saveable.....

thanks !

---

Dammm!!!! :pout:

It's really very sad :/
9AppsCartoon HDVidmate

Most of the people on here, when buying a sub, turn to forum user Nik Brewer to get one of his "uber-stealth" sub boxes and with an added Pioneer TS-SW2501S4. If you're looking for super mega bass, though, I would go with the 13" slim mount JL Audio sub and an appropriate box.


For amps definitely get a compact digital amp that fits under either a front seat (like the Alpine or JL Audio compact digital amps) or a small amo that can be fitted under the hatch floor liner.

Quote:

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Originally Posted by barryallen1337

Most of the people on here, when buying a sub, turn to forum user Nik Brewer to get one of his "uber-stealth" sub boxes and with an added Pioneer TS-SW2501S4.

---

We do?

https://static1.fjcdn.com/comments/W...f0ce279df3.jpg

Quote:

---

Originally Posted by barryallen1337

Most of the people on here, when buying a sub, turn to forum user Nik Brewer to get one of his "uber-stealth" sub boxes and with an added Pioneer TS-SW2501S4.

---

Who?

Quote:

---

Originally Posted by barryallen1337

For amps definitely get a compact digital amp that fits under either a front seat (like the Alpine or JL Audio compact digital amps) or a small amo that can be fitted under the hatch floor liner.

---

I don't use any of the brands mentioned.

Quote:

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Originally Posted by barryallen1337

Most of the people on here, when buying a sub, turn to forum user Nik Brewer to get one of his "uber-stealth" sub boxes and with an added Pioneer TS-SW2501S4. If you're looking for super mega bass, though, I would go with the 13" slim mount JL Audio sub and an appropriate box.


For amps definitely get a compact digital amp that fits under either a front seat (like the Alpine or JL Audio compact digital amps) or a small amo that can be fitted under the hatch floor liner.

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a hammerless .38 special will work [ in the console/consealed ]. Interesting "first post" , barryallen1337 { who is07-20-2018

https://www.caraudiojunkies.com/ozzm...s/goto-top.png #1

Lurch }

Quote:

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Originally Posted by barryallen1337

Most of the people on here, when buying a sub, turn to forum user Nik Brewer to get one of his "uber-stealth" sub boxes and with an added Pioneer TS-SW2501S4. If you're looking for super mega bass, though, I would go with the 13" slim mount JL Audio sub and an appropriate box.


For amps definitely get a compact digital amp that fits under either a front seat (like the Alpine or JL Audio compact digital amps) or a small amo that can be fitted under the hatch floor liner.

---

Is Nik also from Gorakhpur?

Quote:

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Originally Posted by Lurch

Does anyone know what would cause an amp to fail in the upper bass registers ?

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I would expect this problem to be a capacitor problem in the power supply, since that's what provides that super fast power at higher frequencies. But, I don't and have never repaired amps, so just a guess.

Quote:

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Originally Posted by BigAl205

Is Nik also from Gorakhpur?

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is that near Bangladesh ?