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Is a Sub really necessary for Home Theatre?

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  • #16
    I can agree with that. *NM*



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    • #17
      Re: Pete, would you mind explaining?


      > Hi Brian,
      > maybe the max voltage the supply can give is
      > what he is talking about. there's only so
      > much current per voltage that can be
      > expected before PS runs into problems but it
      > seems to me that due to the nature of low
      > frequency, if you cut back on an HT recvrs
      > low freq power to other speakers, shouldn't
      > it allow more current for the truly fuller
      > range speakers or am I wrong here?

      The current drawn by the drivers is determined by the voltage applied. It's really that simple. Your amp is likely current limited by a protection circuit. That's why most of them will not handle less than 4 Ohm loads. They'll draw too much current and possibly damage the output devices.

      There's no doubt the M.C.L.s will handle ANY 100W amplifier easily. But when you start putting higher power gear on them for LFE, you are taking a big chance. LFE on many movies has a LOT of content below 30Hz, and if your woofers are not designed to handle it, you could easily damage them. A 20Hz tune on the enclosure can help by limiting excursion around 20Hz, but there are movie LFE tracks that go to 10Hz. So if you're going to power the MCL with 250W, make sure you have a rumble filter to protect your investment until you have a sub designed to handle that.

      R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio
      Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51

      95% of Climate Models Agree: The Observations Must be Wrong
      "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

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      • #18
        Re: Finding out . . .


        > BE CAREFUL!!! LFE can cause HUGE peak draws
        > of power, at very low frequencies (below
        > 30Hz).

        > You might just find that during
        > "Finding Nemo" that you'll find
        > your speaker cones in your lap!!!

        Now that'd be quite the "lap dance"!
        :-)

        GC

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        • #19
          Re: Is a Sub really necessary for Home Theatre?

          Provided Link: Daryl's Speaker Stuff.


          Hi AJ,

          Actually I was being conservitave.

          Dolby reference level is 105db per channel at the listening position for a signal recorded at 0db (biggest sine wave that will fit into the digital system).

          In a small room each speaker might be 2.5 meters from the listening position which would mean the 1 meter spl would be 8db higher or 113db.

          The MCL speakers have a 1 meter sensitivity of 91.5db which boils down 21.5dbw (140w) from the amplifier for the main LR channels alone.

          The LFE channel is capable of levels 10db louder than the five main channels 115db at the listening position.

          Since the LFE channel is divided between the L and R channels in this setup and you will subtract 6db from the +10db for the LFE channel in the LR channels.

          This Boils down to +4db over the level required for the main channels to reproduce the LFE channel in each LR channel.

          This adds up to 25.5dbw (350W) for the LFE channel alone in each LR speaker.

          Now to add the LFE channel to the main channel in the LR speakers you would call the voltage required for the main channel 1.

          The LFE channel in each LR speaker is potentially 4db higher than the main channels which indicates a relative voltage of 1.6 times the voltage of the main channels.

          Add them together and the relative voltage is 2.6 times the voltage reqiured for the main channel or +8db.

          Adding 8db to 21.5dbw gives you 29.5dbw (900w) into each speaker for the LFE channel plus main channel.

          Daryl

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          • #20
            Re: Is a Sub really necessary for Home Theatre?


            I understand this.

            But buying a 400w/pc amplifier to power the speakers in question? The woofers will bottom out before you use all of that power. Not to mention thermal limits. Like i said before, I'm all for headroom. But i also believe anything beyond 300 w/pc in a home enviorment is overkill for most speakers.

            I also believe in quality over wattage ratings. I'd rather know how good my system is going to sound rather than how much my electric bill is gonna be. Thats why i said pick up a good quality amplifier of around 250w/pc instead of paying for a crappier sounding amp that puts out 400w/pc.

            But this is my own opinion. Nothing more nothing less.

            P.S. Either way it will sound better than using the HT reciever as your mains amplifier.
            "I have not failed. I've just found 10,000 ways that won't work." Thomas A. Edison

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            • #21
              Re: Is a Sub really necessary for Home Theatre?

              Provided Link: Daryl's Speaker Stuff.


              Hi AJ,

              The 900W figure is due to the fact that voltage peaks from the combined main/LFE channels can coincide.

              The average power would be much lower than normal due to two signals being added (adding two non-correlated signals with the same level increases average power two times while peak power is increased four times).

              The MCL speakers have two 12" woofers in each cabinet in a vented alignment with a high Fb which doesn't give the greatest bass extension but does make them hard to bottom out.

              Daryl

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              • #22
                Re: Is a Sub really necessary for Home Theatre?


                Well then crank up da' power, watch the lights dim and rock on man!

                Anyway, Jim, take a look at what QSC and Crown has to offer. An amp that actually puts out what the company rates it as would be a great start.
                "I have not failed. I've just found 10,000 ways that won't work." Thomas A. Edison

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                • #23
                  No.


                  I frequently turn off my sub when watching movies at night, since the deep bass travles through the house. I don't notice the absence all that much. And I'm using 6.5" 2-ways.

                  The thing about home theater is that the action on the screen helps you to psychoacoustically l;oaclize the sounds coming out of the speakers, just as quality sound adds realism to the action on the screen.

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                  • #24
                    Re: No.


                    > I frequently turn off my sub when watching
                    > movies at night, since the deep bass travles
                    > through the house. I don't notice the
                    > absence all that much. And I'm using
                    > 6.5" 2-ways.

                    > The thing about home theater is that the
                    > action on the screen helps you to
                    > psychoacoustically l;oaclize the sounds
                    > coming out of the speakers, just as quality
                    > sound adds realism to the action on the
                    > screen.

                    once again, the responses from all of you are greatly appreciated and thank you all. my decision is to try w/o subs @ this point. and then see what happens. who knows!?!
                    again, thanks,
                    Jim

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                    • #25
                      Sub needed with Magna *** Laude!?


                      In the review of that speaker, someone writes that it might be even better with a subwoofer. Why does a speaker with two 12" subwoofer drivers per side need a sub?!?!

                      Maybe he wants to compensate for a perceived lean character of the Magnas with a sub, which is not an appropriate thing to do, IMO. The system can be fairly easily adjusted for more warmth, with the tone controls if nothign else. Adding more bass drivers is silly.

                      <A HREF="http://www.partsexpress.com/projects...uencychart.jpg">http://www.partsexpress.com/projects...uencychart.jpg</A>

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                      • #26
                        Are Magna *** Laudes really necessary with a sub? *NM*



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