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  1. #1
    CAR REVIEW ADMlN Registered Member Easy E's Avatar
    Join Date
    Dec 2003

    Amplifier Settings Tutorial: Gain, Subsonic filter, Crossover, Bass Boost, Fuses etc

    Gain is like a volume knob on a stereo. More you turn it up more the stereo will amplify the input signal. The problem is your input signal can exceed the amplifiers output. The signals will then clip which causes distortion and no more power out of the amp. Problem is each HU has a different output of a signal, so the amplifiers gain needs to match that input signal.

    Like in my stereo in my truck, I have my gain like 15% up. That way when I reach 45-50 on my HU the amp is about maximum power. Now if I had my gain all the way up then the max I will be able to turn my HU is to about 15 or so before I reach max power output.

    Input Sensitivity
    Same thing as Gain.

    Crossovers limit frequencies going to a subwoofer. Higher order like 4th order instead of 2nd order, steeper the slope is of the crossover more effective it is. Crossovers gradually reduce frequencies. For more information check out this link.
    Set woofer crossovers low pass 60-100hz depending on the sub midbass etc. 80hz is a good area.
    Set the high pass crossover for your speakers to the same number as your woofer typically around 80hz.

    Subsonic Filter:
    Now Subsonic filter is a crossover, that limits extreme low bass going to your subwoofers. if you are running sealed set it as low as possible if you are running ported set it 5-10hz bellow your tuning of your sub.

    Setting the steepness of the crossover slope. See Crossover

    Infrasonic Filter:
    This is the same thing as Subsonic Filter. Commonly found on JL amps.

    Phase changes the relative phase of the outputs on the amplifier. This is not that helpful in most situations.

    Bass Boost
    This amplifies a certain frequency. Sometimes it has set, usually around 40 Hz other amps have a variable frequency rang. The higher the bass boost is set more the amplifier boost a certain frequency. In typical installations, bass boost is not recommended to be on.

    [B]Center Frequency:[B]
    This is found on many JL Audio amps, it is where you want the bass boost to kick in. See EQ.

    This is like a bass boost, but usually is variable. Don't worry about this.

    This is for EQing, smaller the Q more gradual the slope is for EQing. Usually you do not mess with this since you do not use the EQ on the amplifier.

    Power Wire
    10 GA wire is good to about 200-watt amplifier
    8 GA wire is good to about 500 watt amplifier
    4 GA wire is good to about 1000 watt amplifier
    2 GA wire is good to about 1700 watt amplifier
    1 GA good to about 2200 watt amplifier
    0 GA is good to about 3000 watt amplifier.
    These are rough numbers and depends on how long the power wire is ran.

    Ground Wire
    Try to make this as short as possible. The shorter the better. Keep it shorter then 3 ft or alternator wine can happen. Also, try to keep it the same GA as your power wire.

    Use only the same size fuses as your amp recommends. For fusing the power wire go with about 10 amp higher then all the components fuses combined running off that power wire. Fuse 6-18" from the battery, any shorter can cause corrosion, and any farther can be risky.
    Last edited by Easy E; 03-28-2006 at 18:50.
    Thats my 2 cents.

  2. #2
    Senior Member Registered Member KirK's Avatar
    Join Date
    Jan 2005


    Hi Easy E. I just want to commend you for taking the time to develop this post. I just want you to know that CVStroker and yourself are remarkably intellect when it comes to audio. I have learned so much invaluable knowledge from both of you. Much more so than any of those morons gave me at Tweeter who tried selling me JL Audio equipment for MSRP. I have a great deal of respect for the both of you. CVStroker and Easy E are an asset to the Carreview.com car audio forums. Its ashame that we have wise guys that come here and underestimate the audio knowledge that you two possess. Speaking, of which, I am still sorry for what I said in that one forum long ago. I was exposed to my parents' failing marriage at that time, and I guess I was emotionally messed up then. Since I started to talking to you guys I rapidly improved as a human being. I am very thankful to have met you two in the forums.
    I want to also take this moment to apologize for acting like a know-it-all and being a post whore at times. I know my intellect in audio is far from rivaling the expert knowledge that you two have. I am sorry. Sorry for replying to a dead post. I just wanted to give credit to where credit is due.
    Antisocial behaviour is a trait of intelligence in a world full of conformists.

    -Nikola Tesla

  3. #3
    Junior Member Registered Member
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    Oct 2009
    thanks for this wonderful post....i was just wondering what does crossover mean....you made it clear...

  4. #4
    Junior Member Registered Member
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    Oct 2009
    This was really a nice tutorial. Very well described. Thank you for this.
    To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

  5. #5
    Junior Member Registered Member
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    Nov 2009
    why is it necessary to make ground wire as short as possible..
    Michl87 Best Cigars

  6. #6
    CAR REVIEW ADMlN Registered Member Easy E's Avatar
    Join Date
    Dec 2003
    I said it needs to be as short as possible or you will get alternator whine. If you want to know more google it, or click here.

    Thats my 2 cents.

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