Question for all the stereo guru's

[SHO2NV]

Ok, first off this is what I have:
Pioneer GMX-802 amp w\2 12" MTX subs

I have this hooked up thru the factory system. Here's the thing...at low volume(about a 1/4 way up) it has alot of bass, but at 1/2 way up the bass seems to fade away, it's really loud, just not much bass. I was wondering if this is because the deck. I read in the ownwers manual that the deck has something built in to it to keep the sound from distorting so do you think this is also keeping my amp from putting out the max power? I had this same set up in my old car hooked thru the factory system and it had ALOT of thump. Any help on this would be mucho appreciated.

Thanks

 

[92shoiowa]

ok i'm no expert but i have F*ed with this crap so much
lol
Check the gain.......it may be to high
turn it to around 90 if possiable......keep it lower that 90 and bass boost barly on.....
that may help i dunno thanks

 

[SHO2NV]

Nah, I don't think it's the amp, I didn't change anything from my old car to my SHO, and it really thumped in my old car. I'm really thinking it's the factory deck. Anyone else have any idea?

 

[SHO T1ME]

Hehehe, alot of thump -- oh boy, I would hate to hear what you call my two tens getting pushed by a 1600 watt amp!

To be honest, ive never messed with SHO audio systems, but that will all be taken care of soon. Based upon what you have told me though it does sound like the headunit is limiting power to prevent distortion... kinda cool that it does that, save you from buying new subs cause you fed the damn things too much distortion. But, again im not an SHO audio guy just yet but good luck thumbs_u

 

[gatzby143]

The problem is the stock head-unit lowers/limits the bass output as you raise the volume to prevent distorton in the stcok speakers and stock sub.

 

[Jibberish18]

Don't quote me but it sounds like your box is to big for your speakers. But this may not be the case. I had my 8" in a HUGE box around .70 cubic ft. bigger than what I was supposed to have it in. Bass was amazing at low levels but was gone at high levels. HOpe this helps.

 

[GEN1SHO]

Jibberish18 has a good point. Make sure the box your subs are in is made to the manufacturer's specs. They can probably be found on their website. What you are looking for is the volume of air inside the box, measured either in cubic feet or liters.
If it's not close to what it should be, you will get all kinds of weird performance issues with your speakers.
What kind of box is it? Sealed, ported, bandpass, etc.?

 

[GEN1SHO]

Also, what kind of subs? (Make, Model, etc.)

 

[naval-avi8or]

I've got a 8" sub in exactly the right size box. Mine dose the same thing with the factory system but not when I was using aftermarket head unit and amps and wireing. It is the factory system that does it.

 

[SHO2NV]

Yeah naval, that's kinda what I figured just wanted some more opinions. Big thanks to everyone who replied.

BTW, the speakers are 12" MTX in the original MTX enclosure they came in.

So I guess I'm gonna look for a nice head unit, what are the good double din units out there? Not too pricey though, it doesn't have to top of the line, just good.

 

[naval-avi8or]

Just make sure you rewire from your head to your amp (rca). If you use one of those harness addapters at the factory amp you may get the same result.

 

[Jibberish18]

Yeah naval, that's kinda what I figured just wanted some more opinions. Big thanks to everyone who replied.

BTW, the speakers are 12" MTX in the original MTX enclosure they came in.

So I guess I'm gonna look for a nice head unit, what are the good double din units out there? Not too pricey though, it doesn't have to top of the line, just good.

In that case it may be doing that because your amp needs a headunit with higher preamp voltage maybe? All aftermarket headunits I've seen run at least 2 volts.

 

[DJ SHO]

All you need to do is a little tweaking that's all. Believe it or not the factory head has balanced outputs (separate grounds for each channel, no common ground) for a clean signal. I spoke with a tech at an audio repair facility that works on factory equipment (ford jbl systems included) and he answered a lot of questions for me. Splicing in a pair of RCA cords to the wires coming from the deck, then going through a ground loop isolator, will give you a noise-free signal of at least 4 volts output to go into your aftermarket amps with. My amps are actually turned down a bit because the output is that high. Compression helps prevent distortion (which blows speakers) by lowering the volume of certain frequencies that are peaking higher than the others. Play around with your gains a bit and set a limit on your factory deck, perhaps 4-5 bars from the end of the volume indicator, where you want maximum volume. Then if you pass that point it will compress the sound and not get distorted. A good way to protect your speakers from those friends who think they can beat the crap out of your stereo. thumbs_u
Also, you might want to add an EQ in between the deck and amplifiers.

 

[Jibberish18]

You go with yo bad self!

 

[naval-avi8or]

I tryed to post this before the forum went down but it didn't go through. Here is the info about the reson why your bass is loud and then fades away.

Volume and Tone Controls
--------------------------------------------------------------------------------
Thanks to Steve Reynolds. All of this information applies to the Premium Sound System in Steve's '95.
Volume The volume control has 30 positions. The first position is off. After that there is a 2 dB (decibel) change per position. 2 dB louder going up and 2 dB softer going down. With the tone, balance and volume controls centered with music playing on the radio the average sound pressure is 88 dB. The maximum volume without noticable distortion is 110 dB.
Automatic loudness The head unit has built in automatic loudness control. This means the bass frequencies are louder at lower volume levels. This is because our ears think the bass falls off faster at lower volume levels. This way the bass sounds constant relative with the rest of the music. At 100 Hz the volume control works a little differently than stated above. Every third step the bass volume goes 1 db in the wrong direction. For example, when decreasing the volume from the middle position downward, the first step reduces all music 2 db. The next steps also reduces all the music 2 db. On the third step all music except the lower frequencies decrease by 2 db while the bass frequencies increase by 1 db. The bass is now louder than the previous higher volume step.
Bass and treble The treble control has 15 positions. There is no change between the 2 lowest positions or the 2 highest positions. There is a change between each of the other steps.

The bass control has 15 positions. From the center position the bass only decreases for 5 positions and from the center the bass only increase for 3 positions. There is no change through the remainder of positions.