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Amp settings for JL e6450M

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  • Amp settings for JL e6450M

    I have a 2006 X15 with two tower speakers and subwoofer. All the audio equipment is stock just as it came out of the factory. I am a greenhorn when it comes to amps. There are a couple of settings on the JL e6450M amplifier that do not seem correct to me after reading the manual.

    Here is how the setup looks:
    -RCA inputs for Ch. 1, 2, 3, and 4. Ch. 5 and 6 inputs are empty
    -Ch. 1 and 2 speaker outputs go to the four cabin speakers
    -Ch. 3 and 4 speaker outputs go to the two tower speakers
    -Ch. 5 and 6 speaker outputs go to the subwoofer and this connection looks to be bridged

    -Ch. 1 and 2 controls have filter mode off
    -Ch. 3 and 4 controls have filter mode set to High Pass at 150 Hz freq. (This is my 1st question, seems to me that the filter mode should be off for the tower speakers so they can get full range?)
    -Ch. 5 and 6 controls have filter mode set to High Pass at 80 Hz freq. (seems this should be set to Low Pass for the subwoofer, correct?)
    -Ch. 5 and 6 controls have the Input Mode set to Sum
    -Ch. 5 and 6 controls have Bass Boost set to ON (The manual is confusing on this one, see below)

    From manual: "Bass Boost (Channels 5&6): This switch allows the user to activate a 6 db boost centered at 48 Hz for channels 3&4. When the Bass Boost in the Channel 5&6 Controls section is activated, the inputs to CH 5 (Left) and CH 6 (Right) are summed to create a mono signal. The filter mode switch in the Channel 5&6 section must be in the LP position for the bass boost to be functional."
    #1 Since I don't have any inputs for Ch. 5 and 6, shouldn't this be turned off? #2 Why would the bass boost go to Channels 3&4? Is that a typo, seems like it should go to 5&6 for the subwoofer?
    We defy the mafia!

  • #2
    Channels 1 and 2 should have the High pass filter on and set the frequency at 80-100 hz.
    Channels 3 and 4 should have the High pass filter on and set the frequency at 80-120 hz (the higher the frequency, the less 'bass' you will hear, but they will project a little farther).
    Channels 5 and 6 should have the Low pass filter on and set the frequency at 80 hz. Turn the bass boost off. I don't think the bass boost switch has anything to do with bridging channels 5 and 6 (mine is certainly not turned on).

    Here is JL's recommendation for frequency settings for satellites and subs:

    Tuning Hint:
    If you are using the M6600 to drive a subwoofer system (“LP” mode), a component satellite speaker system (“HP” mode) or both, 80 Hz is a good baseline “Filter Freq. (Hz)” setting. After properly adjusting the “Input Sens.”, as outlined in Appendix A (page 14), you can fine tune the
    “Filter Freq. (Hz)” control to achieve the desired system frequency response.

    I believe the input mode should be set to 'Sum' since you are only have RCAs to channels 1 -4.

    Make sure the head unit is flat (no bass boost or loud turned on). Turn the headunit to approximately 75% volume and adjust the sensitivity on each channel until you hear a slight distortion then back the sensitivity down a little.


    • #3
      Do NOT use any bass boost in an open boat. It robs you of too much power with very little audible benefit and is just likely to introduce distortion.
      The tower zone should always be 'Highpass'. You cannot get fullrange from any speaker in a small pod. Most tower speakers start rolling off naturally at 200 Hz and drop like a rock below 100 Hz, so why add the extra stress to the amplifier and speaker with no audible gain. The tower speakers will play louder, cleaner and project farther if the amplifier highpass setting mimics the speakers natural tendency. 100 to 125 Hz depending on the speakers is usually good.
      The in-boat coaxials (highpass) and subwoofer (lowpass) should be set at a symmetrical frequency. It's counterproductive to protract the phase shift of these two filters over a broader frequency range. Keep the crossover overlap tight.
      80 Hz lowpass is often a good starting point in a home or vehicle. A little higher setting will often do better in the open environment of a boat.


      • #4
        Thanks to both for the quick answers.

        David - Just need a little clarification on "symmetrical frequency" in your statement. I believe you are saying that the in boat coaxials should be set to 80 Hz as HP and the subwoofer should also be set to 80 Hz as LP. Is this correct?
        We defy the mafia!


        • #5
          'Symmetrical' does mean the 'same'. But usually, and especially with a 10-inch IB woofer, 80 Hz is too low. 50 to 80 Hz is where you perceive most of the bass energy. Either a sealed or IB 10-inch will begin rolling off fairly rapidly just above 50 Hz in an open field environment. With an 80 Hz filter you are already rolling the response off about 1/3rd octave beforehand and are at 50% power level at the stated filter frequency. So at 80 Hz you have decidedly narrowed the bandwidth of your woofer contribution. It's actually working harder to deliver less perceived output. So begin at 100 Hz. The best sounding woofer is working the most conservatively.


          • #6
            The CMD4 in my boat has two non-fadeable RCA outputs which are not hooked up to the amp. Why would the factory not use these hooked to the amp's ch. 5 & 6 inputs?
            We defy the mafia!


            • #7
              Originally posted by blackhawk View Post
              The CMD4 in my boat has two non-fadeable RCA outputs which are not hooked up to the amp. Why would the factory not use these hooked to the amp's ch. 5 & 6 inputs?
              They could. If those are used for the sub chnls, the sub level would be tied to the head-unit volume and not be effected by front or rear fade. Personal preference, as some like the sub level to be tied to the full range in-boats, while other like it tied to the tower and others like it pounding all the time. If you have a sub level controller of some kind, using the non-fade is perfect.


              • #8
                Yea, it says in the manual that the outputs are full range and you can set their level in the head unit menu. It says you can set them to -6 to +6.
                We defy the mafia!


                • #9
                  I have the same set up and amp and boat.

                  My one e6450M is powering the 4 JL tower speakers, the four JL cabin speaks and the JL sub.

                  One amp and 9 speakers? What were they thinking.

                  I think I'm going to add the JL M400 for the tower.
                  Former: 2007 X15