aznboinghia

Okay i have a setup with

2x Digital Deisgn 1508 subs
with a custom box enclosure at 1.75cubic feet by 35HZ

Running on a
JBL GTO7001 Amp
Pushing at 2ohm makin up to 700rms

Signal from a
JVC AVX800
Preout amp at 5v

700rms /2 = should be roughly 350 rms underated power coming from my JBL

PROBLEM!:
In order to get get a decent amount of bass. I had to crank my JBL at 75% percent gain. Running 80hz LPF. WHY? .. it should not even be that high to even make the 8's hit. and These DD are capable are monsterous bass.. To get good bass not very good bass i had to crank it to max.. im scared of clipping my new amp. Please Help =(

SOLUTION?: MAYBE!?!
Well.. i'm thinking that it may be my wiring.? Could it be? i have a 4gauge running from battery to back. Hook onto a distributer 4gauge in - 2x 8gauge out. But the out - is 2x 4gauge wires push tightly into the 8gauge holes. The wire is extremely stiff. and not sure that may be the problem.. and incrediably sticky inside dont know. i found it :O lol. PLEASE HELP

titan

Make sure the subs aren't out of phase. Unhook one, and switch the wires to the opposite way you had them before. You get more bass, they were out of phase. If thats the case, follow your wires back to the amp, and find which one was wrong, and correct it.

Check the ground on your amp too. Don't put it under some bolt you find inside a panel somewhere. Find where the frame rail is running under the car, and drill through the floor into it. Sand off all the paint around the hole, and mount your ground there, with some good size screws.

Really sounds like they're out of phase though.

aznboinghia

Hmm.. well my ground is really half *** lol. i might have to0 check it.

As far as of out of phase. So your telling me to switch the positive to negative and negative to positive ? Isnt that bad for the subs?

Hmm.. at work right now. So ill try that when im off. Any more thoughts? please let me know

Gambit69

As for switching the wires on the subs, no it will not hurt them. Not sure how to really explain it but the pos and neg on the subs really just tell the subs to either push out or pull in depending on the signal. They get the signals so fast you couldn't tell. If you have the wire coming from the positive on the amp and hooked into the negative on the sup, just make sure that the other sub is hooked the same way. What is happening is that if you have one hooked pos to pos and neg to neg and the other is pos to neg and neg to pos the subs are fighting each other. When one is pushing out the other is pusing in fighting each other. Just switch the wires on one of the subs to see if it gets better. If it gets worse and there is less base than before that it was right to begin with and you may need to chech somewhere else. Hopefully I didnt confuse you at all but just switching the wires around will not hurt the subs in anyway.

aznboinghia

Okay i Will try it. But as far as any other problem? would it be reasonable that the amp not strong enough to power subs ? Which i highly doubt. What other possible reason that the amp has to be near max gain to push my 2 tiny 8's.

The 8's are rated at 400RMS/1500PEAK.

Gambit69

It could also be that they are 8 inch subs. I have had 8 inch subs before and only used them for midbase since they are small they dont give out much base. This is just the experience that I have had with them. Your subs might be diffent than the ones I was using. I was running MTX 8 inch subs and they did the job for mid base but not much for the main base. I was usning bigger ones for that.

1991CamaroRslow

iTrader: (3)

Your "5 volt" pre out could be a bunch of BS. You could have it on the wrong output and be sending it a highpass signal, this would explain why when you crossover it lower than 80hz you lose alot of performance. I don't get what you are asking though, who cares what the gain is set at, if the subs aren't clipping and sound good leave it that way. You could also run a DMM and find out what actual power you're sending the subs.

aznboinghia

well it running though the subwoofer out preout and as far as the 5v. my vmeter measure it to 7v coming to the preouts.

well. these subs are built for SPL. The Fact that it is 8's does not mean it cant give out bass lol.

http://www.ddaudio.com/dd/caraudio/w...sp?series=1500

and as far as the amp goes. Max gain on a amp is always gonna be bad. It will clip =/

Any other explanation why?

2fast4u92z

Check your speaker wire and see if you are running 2ohm or 4ohm.
80hz if fine
The "stiff wire" is bad. As the more fine strands are better
Asume you pluged the preouts to a sub out and the radio is set right!
What are the fuses on the amp rated at? I have a feeling that this amp makes nowhere near that power!

aznboinghia

Yea it all correct lol. I'm Running a secondary amp also to power my highs. and the setting on my radio is right to. lol not a complete noobie :O

http://www.jbl.com/car/products/prod...at=AMP&ser=GTS

That the amp. This amp is not a cheap one 350 retail. and it also underated.

and the subs are wire to 2ohms. It just straight wiring that all. Since the amp got 4 input for wires. it already bridge inside. the subs are SVC 4ohms. Wire 2 to a mono block would give me a 2ohms load.

klez

iTrader: (1)

yes, DD is a huge name when you are talking to people that are really into subs. The average person just doesnt know about the company because they arent sold at best buy or circuit city.

Anyways.... it sounds like a bad connection to me. i would check all of your wiring. That is where your problem lies. Check power clear from the battery to your amp. check your ground, make sure its on uncovered metal. and check your sub wiring. here is a great website for DIY car audio, use this to figure out how you need to wire them if you arent sure.

http://www.the12volt.com/caraudio/wo...s.asp?Q=2&I=22

aznboinghia

Okay I just redid my ground. Extremely Well. REally well lol.
and i check if it out of phase. And wire perfectly fine.

What else now? =(

2fast4u92z

Not trying to beat a dead horse but you should meter the subs. Just unplug the sub wires and meter them to see the ohms. From your post it sounds like the positives are all going to the amp and same with the negative. If they are dual 2ohm each sub then you want the middle pic. In the 12volt link that was posted.


Oh and your amp isn't bridged inside. It is a mono so even though you have many speaker terminals it is a one channel amp. There is a major differance in mono and bridge.

klez

iTrader: (1)

well actually if i am not mistaken, it should be the first pic in this link since his subs are single 4 ohm voice coil,and are supposed to be wired to 2 ohms at the amp... http://www.the12volt.com/caraudio/wo...s.asp?Q=2&I=41

2fast4u92z

Your right. my mistake I thought they where DVC.

aznboinghia

okay i just tested my friend kicker sz750.1 and it beated nicely at half gain. Ahh.. it cant be my JBL it brand new and GTO series. it should be giving out almost same output.