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Thread: Help me push my subwoofers to the max

  1. #1
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    Help me push my subwoofers to the max

    I finally got around to buying a better amp for my subwoofers. I had a pioneer GM-5300T, this amp was only feeding my subs 125 watts rms each. I bought a Kenwood-KAC-8103D, this amp is feeding the subs 250 watts rms each. I am using it with 2 JBL GT4 12" subs which take 250 watts rms each. They are wired to put a 2 ohm load on the amp. I am not sure how big my enclosure is because I bought a prefabbed one and I am not very good at building stuff like that. I would estimate each sub has about 2 cubic feet of air, maybe more. The enclosure is sealed. My carpc has a sound blaster live 24 bit PCI sound card.

    Here are some pics of my equalizer and amp settings.



    The problem I have is I was expecting a lot of bass. More bass than I would have even wanted. Maybe I am naive, but I am disappointed. I listen to music like megadeth, so I am wanting loud drum hits and loud bass guitar notes. I actually cant tell much of a difference between my old amp and my new amp. If I turn up any setting any higher my amp goes into power protect mode. So even at high volume, and low gain everything is still not very loud.

    I have upgraded the big 3 wires, checked all of my connections, and everything checks out. I am using 4 gauge wires all the way to the amp, and 6 gauge wires to the subs. The amp gets about 12 volts, but when idle it drops to 11.5 on hard bass hits at max volume. I would assume driving down the road it gets 12 volts, but maybe I am wrong.

    I am not an expert, or anything close to it, so can someone give me some pointers and explain what I am doing wrong? Am I expecting too much from my system?

  2. #2
    Neither darque nor pervert DarquePervert's Avatar
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    The bass boost setting at 0db might be one reason...
    Have you looked in the FAQ yet?
    How about the Wiki?



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  3. #3
    MySQL Error soundman98's Avatar
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    no. darque, your falling off your game! bass boost artificially enhances certain freq-- which can led to destroying subs when you push them to play a freq that they shouldn't normally play that loud.

    according to my old knowledge, doubling the power supplied to the subs will have a increase of about +3db. humans can usually tell a difference at a minimum of +6db. so there isn't much you can do with teh amp setup.

    one of the things you can try is to move the box around in the trunk, and experiment with it facing certain directions, sometimes this can help get louder bass as well.

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    Turning the bass boost up even to 1 will make the amp shut off pretty quick. After some searching I think it may be my equalizer. I am going to re-tune it again with the equalizer turned off. I know these subs can play so much louder because when I turn up the settings to a level that sounds nice the amp cuts off after about 3 minutes.

  5. #5
    FLAC PhilG's Avatar
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    If the gains are at the top, something is definelty wrong. I would recommend googling "setup up a car audio amp" or something similar that gets you the results. You will need, at minimum a DMM.
    My 2007 Ford F350 Work Log located HERE

  6. #6
    Neither darque nor pervert DarquePervert's Avatar
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    Quote Originally Posted by soundman98 View Post
    no. darque, your falling off your game! bass boost artificially enhances certain freq-- which can led to destroying subs when you push them to play a freq that they shouldn't normally play that loud.
    I concur, but if you want to get bass from your sub (which is it's purpose anyway), increasing the bass frequencies at the amp should also increase the power to the subs, at least in my mind.
    Granted, it's not anything you want to crank all the way up at one time. I would think bumping the bass boost up a level to determine how it improves the bass couldn't hurt...
    Unless it kills the amp, as the OP said it does.

    I'm the first to admit that settings on specific pieces of equipment aren't my area of expertise.
    That's probably why I haven't tweaked my amps.
    I probably should.
    Have you looked in the FAQ yet?
    How about the Wiki?



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  7. #7
    MySQL Error soundman98's Avatar
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    yes, a little bass boost would not hurt, but in general, people love to crank it all the way to max. so because of this, i stay with the method to keep it turned off, because most don't know how to utilize it correctly, or listen for distortion in their subs.. so combined, these problems lead to sub failure..

  8. #8
    Car Audio Moderator durwood's Avatar
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    If these are the correct specs

    Frequency Response: 28Hz - 450Hz
    Sensitivity: 93dB
    Impedance: 4 Ohms
    Voice-Coil Diameter: 50mm
    Cut-Out Diameter: 283mm
    Mounting Depth: 161mm
    Overall Diameter: 311mm
    Vas: 100.45 liter
    Qts: 0.43
    Fs: 24.75Hz
    Qes: 0.46
    Qms: 6.46
    Sealed Enclosure (vol): 28L
    Vented Enclosure (vol): 64L

    and your box is actually as big as you say (measure to be sure to find the volume), then the box is probably too big (unless you vent it). It needs to be about 1cuft per sub sealed. If you want more output then I would suggest a vented enclosure. If this is in a larger vehicle, you will not have the same gain from the cabin as you would a smaller vehicle so I would say you should look at venting. You haven't said what kind of vehicle this is in. I also notice you have the subsonic filter set at 25hz, that will affect the low lows. However, if you are listening to metal I think midbass should be your focus, but I really don't know what your expectations are or if you heard something else you are using as a reference.
    Last edited by durwood; 06-11-2011 at 03:49 PM.

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    I measured the box and I came to about 1.9 cubic feet per box. L30 X W18 X H 13 for the whole box. So I guess my box is twice as big as it should be. I have the setup in a 2000 cavalier with the back seat down.

    I did set my equalizer to default and turned up the low pass filter to 100, the bass boost to 1, and lowered the gain by a hair. I managed to rattle off my rear view mirror, and my amp hasnt shut off(yet). The bass is pretty good now, but now I want to see about stuffing the box to cut its volume in half. I actually want to keep the box because I mounted all of my equipment too it so I dont have to mount it to my car. What is a good material to stuff the box with?

    About the subsonic filter... If my sub only plays down to 28hz my understanding is that it would not affect the output. Am I wrong?

    I was also thinking about tossing my 4x6 phoenix gold front speakers for some 6.5" alpine speakers to increase my midbass since that is what I am currently lacking. I also have some kenwood 6x9's in the back and I am not very happy with their performance. If the alpine speakers sound good enough I may take out the rear 6x9's so I can keep my back seat up and let the bass come through the speaker holes.

  10. #10
    FLAC PhilG's Avatar
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    If you can, go with the type "R" 6.5", not the "S". My ears, at least, can really hear the difference. Not a bad plan dumping the rears and running front stage only. What amp are you driving the fronts with, the leftover Pioneer?
    My 2007 Ford F350 Work Log located HERE

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