Remyngton

Hello,

I have an '04 with the stock stereo (non Bose) and I recently installed an amplifier and sub in the trunk. The question is, when I turn up the volume past 18 or so, it doesn't seem to increase the bass anymore, just the internal volume. Is there some sort of EQ that turns the bass signal down as the volume increases as to not blow the factory speakers? If so, is there something that can be done to fix this?

WikkedOne

It's probably the amp or the subs that you are using maxing out.

Remyngton

I should have included that info, they are nowhere near maxing out.

Alpine MRD-M605 amplifier with 600RMS (birthsheet says 655 @ 2 ohms) powering a single Polk Audio SR124-DVC rated at 700 RMS wired to 2 ohms.

I know they aren't maxed, if I listen to a bass heavy song like rap, there is more bass, but if I listen to something with less bass, it still happens.

At lower volumes (6-12) everything sounds bassy, then at mid to higher volumes (18+) the bass doesn't increase very much, if any. There is NO distortion coming from the sub at ANY volume, even max.

I'm wondering if a capacitor would help, since my lights do dim.

DeViLbOi

iTrader: (1)

I think what is happening is that you are amplifying too much of the frequency range so you aren't getting that seperation you are looking for. Also...you may be maxing out the EQ within the amp causing it to just stop. Are you by chance using high level inputs instead of low level?

Remyngton

I think I see what you're saying. I had the bass on the head unit up to +6 and the amp is set on 12db octave slope. When I turn the bass down and put it on 24db slope it sounds cleaner and more powerful on a certain frequency, but not as much all around.

Should I get more power out of 24db octave slope than 12db?

Remyngton

After messing with all of the settings on my amp and on the deck, I still believe it's the output from the deck. Everything is fine until 20+ volume. If I have the volume at 20+ and turn the bass on the head unit all the way down I get very firm punchy bass, but it makes the mids sounds like crap. When I turn the bass up, I lose the punchiness and get an all around sound, more sound on other frequencies, but not so much on the frequency I want from the subs.

Either the head unit is not sending the right signal, or I don't have enough juice going from my alternator/battery to my amp. I'm starting to rule out the not enough juice part though, because if I listen to a song that doesn't have very much bass it still does it but I can get more bass out of it from a different song.

DeViLbOi

iTrader: (1)

Also, it is possible that the stock HU cuts out the bass at a certain volume to save the speakers from being blown.

AustinSBR

I have the same situation with my 04 (stock HU non bose). It sounds ok but definately NOT pushing the subs I have set up. I need to break down and spend the money for the dash kit but I just haven't yet.

There is a HUGE diference when you use a stock HU vs pretty much any decent after market unit.

One thing I did notice though, is be sure to turn the auto volume leveling feature off, that really messed with my EQ's.

Remyngton

Is there anything that can be done other than replacing the stock HU?

AustinSBR

Not really, I know that there are some after market external advanced EQ filters and Bass boosters but I've never personally worked with them. For the most part its always better to have a well chosen after market HU, but the dash kit is $450 by itself which kind of throughs a wrench in things.

nuke0907

iTrader: (2)

this is just my guess, but.......an aftermarket headunit will have a 4V preamp output usually. when you use the stock headunit, it will not be able to output nearly that high. as you're turning your volume up, its just not sending your amp enough signal. try measuring the voltage of your signal wires as you turn the volume up.

Remyngton

Good thinking. According to the sticky in the main section of Interior, Audio, and Electronics the stock HU does not have a preamp output, there has to be a line converter added. I did not install the line converter, I bought the car with it and the wires in the trunk already installed so I don't know what kind it is. I'll see if I can get ahold of a multimeter and check the output voltage as you said.

Tamas

iTrader: (1)

I don't have such a problem - but then I have a 5-channel amp powering the (non-stock) speakers and my sub. With the stock head unit at volume level 12, it's already plenty loud, so I rarely need to go any higher.

Replace your speakers with decent ones, get another 4-channel amp to drive them, and you'll be set. Much better sound fidelity too than what you'll ever be able to achieve with the crappy stock paper cone speakers.

Remyngton

Thanks for the reply, but it's not the inside speakers that are giving me this problem, just the sub, which sounds like an output problem from the HU.

I plan on replacing the mids and highs as well, but I can't spend money on the whole system at once, it's going to take some time. I spent around $600 for the amp, sub and box, so I need to relax for a little bit or my girl will flip on me.

Tamas

iTrader: (1)

But that's exactly why I suggested getting a 4-channel amp. With that, you won't have to up the volume on the head unit to 18 or 20, and you said the problem only appears at those high volume settings.
With an amp, you'll get higher volume at setting 10 than with just the stock head unit's built-in amp at 20. Trouble is, the stock paper speakers won't be able to handle an aftermarket amp, so they'll have to go.

Remyngton

That still doesn't solve the problem of why I'm not getting the full amount of power from my amp and sub. Although I'm not wanting to max out my amp and sub, it's nice to know I have that much power back there, and that I am getting the most out of my money that I spent on them.

Also, it makes the adjustment process much easier, because right now, I have a lot of bass at low level, and then it tapers out. Adding an additional amp and new speakers inside the cabin won't fix that, it will just make everything loud at low volume. A workaround, yes, a fix, no.

nuke0907

iTrader: (2)

right now i have the stock headunit(non-bose) like you do with a LOC off the rear speakers. its hooked up to a kicker ZX750.1 powering a kicker 12" solobaric L7. usually i only go up to about 15 on the volume. so far the only problems i noted were my amp cutting off for a second with bass-heavy songs. i haven't added my capacitor in my system yet, since i'm still trying to find some more wiring. your problem sounds like its not getting enough signal, where mine is the amp not getting enough power. see the difference? in your case with the headlights dimming though, it wouldn't be a bad idea to add a cap.