[adam_rostron]

Hey all..

I have an IDQ12v4 running off a mosconi AS200.2 so it's getting 700RMS @ 4ohms.


I had it in a 1.5cu box that was sealed in the back of my skyline and with the amp gain hardly adjusted off the minimal amount it was incredibly hard hitting and really acurate.

when i moved it into my VW jetta, i went from a 1.5cu box to a 1.8cu box running off the same amp, but I am running it off the factory head unit, which really shouldn't be an issue.....

I can not get the bass to hit anywhere near as hard without pretty much maxing out the gain on my amp - not something I want to do...

the rest of the system is a mosconi 6-8v8, HAT legatia L6SEcarbons and the Legatia ring radiator tweeters ( I'm in love with these tweeters btw) running active off an as200.4


looking for suggestions on what could be causing my issue? I would of thought going to a bigger box the sub should be hitting a fair bit harder. Should I try putting pollyfill inside the box? should I just go back to a 1.5cu box?

 

[JVD240]

You changed the entire system in addition to the box...

I'm thinking it's not a box issue unless it's leaking an ungodly amount.

 

[generalkorrd]

Hey all..


when i moved it into my VW jetta, i went from a 1.5cu box to a 1.8cu box running off the same amp, but I am running it off the factory head unit, which really shouldn't be an issue.....

This likely your problem.

Just to be safe, I would check your sub wiring to see if both coils are wired correctly, or out of phase with the rest of the system.

What is your interface between your headunit and your amp? A cheap LOC maybe? Using high level inputs on the amp? A cheap LOC may very cause you to have to crank the amp gains.

 

[adam_rostron]

This likely your problem.

Just to be safe, I would check your sub wiring to see if both coils are wired correctly, or out of phase with the rest of the system.

What is your interface between your headunit and your amp? A cheap LOC maybe? Using high level inputs on the amp? A cheap LOC may very cause you to have to crank the amp gains.

Hey it's running through a PAC LCPRO7 into my processor, i've tried adjusting the input gain and output gain on the processor but it still seems like i have to put the gains on the amp ridiculously high in order to get any kind of noise out of it...

I will have to double check the wiring on the sub, thanks for that! didn't think of that.

 

[gregerst22]

With everything you've described and the equipment you have I agree that it could be a wiring issue or something along those lines.

 

[cubdenno]

Is the skyline a hatchback and the Jetta a standard trunk install?

Are you certain your factory head outputs an non factory set eq?ie, are you sure the signal is flat, 20-20k, across the entire volume range?

 

[Sine Swept]

^ This, especially with VW do you have a full range signal ?

I like to keep a stock test speaker with leads on it handy. I came up with the idea after dealing with a VW Jetta with the 3 way front setup in the door. I needed a full range signal and poking around with my test speaker I found it.

 

[plcrides]

its the car.

 

[JoshHefnerX]

Wait you went from a Skyline to a Jetta!?!

 

[JVD240]

Wait you went from a Skyline to a Jetta!?!

Could have been a V35... aka G35.

 

[generalkorrd]

Hey it's running through a PAC LCPRO7 into my processor, i've tried adjusting the input gain and output gain on the processor but it still seems like i have to put the gains on the amp ridiculously high in order to get any kind of noise out of it...

I will have to double check the wiring on the sub, thanks for that! didn't think of that.

One thing that others brought up is a proper signal. Many factory heads cut bass dramatically as th4e volume goes up, its a speaker protection thing. That's why MTX made the Re-EQ, its a bass restorer/loc. Also along the full range line, do you have a stock 3way system and are maybe tapping the mid rather than the woofer?

I will bet good money that if you even just toss a test deck in that car, wire it up on the seat, you will see a big improvement over what you have now.

 

[adam_rostron]

Thanks for all the great suggestions!

I'll pull the sub out and check the wiring inside of the box later today/tonight and post back with results.

The sub itself doesn't seem to be missing any notes. i'm running it off the rear 2 way woofer signal.. so it should be getting a full range. I'm yet to put it on an RTA and test this 100%.

The front speakers are also running off the front equivalent and they don't seem to be missing any of the signal. again, I haven't used an RTA yet to double check this.

The car had factory 2 ways in the front as it's only the base line jetta.

In Australia the law is pretty hard on IMPORTS. so I literally can not drive the skyline without being pulled over.. I had my dog on the passenger seat taking him for obedience training and I still got pulled over lol. It was an R33GTST. I still have it, just don't drive it much. I had a build log of it in the build area.

 

[LBaudio]

original hu might be an issue
your new box have lower Qtc, so less "boost" in upper range (higher f3)
totally diferent car....q is if position and facing of the sub is ideal for new car differences might be big (phase cancelation)
and other evergreen problems (wrong coil viring, box not airtight,....)