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  • PA question

    When running through a PA system what levels should I have the mixer and power amp at so I don't damage the speakers or amp? Should I max out the TD-8 and mixer volume and then go up on the power amp? Or should I go about 75% on the TD-8 and mixer and go up on the amp from there? Thanks for your experience.

  • #2
    Studio

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    • #3
      I already run my TD-8 like you described with the faders maxed and the internal mixer tweaked. My PA is 2 dual 15" speaker cabs with horns, 1000 watt power amp and an 8 channel mixer. I'm not getting clipping on either the power amp or mixer but I haven't needed to push the PA for more than house parties. I was wondering If someday I need to push it should I max out the power amp and then move the mixer levels up? What is impedence?

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      • #4
        I have pushed my PA many times (1600 watts continuous program power) and the best way is to turn up your amp first (either max or to your best discretion) and then play with the mixers levels.

        Speakers have an impedence. The speaker impedence is what the amplifier sees as the load. If a speaker is 4 ohms, that is the load at which amplifier sees, so the amps output is at 4 ohms. Most amplifiers run best at 4 ohms. Some are stable at 2 ohms but for
        longevity and to avoid overheating 4 or 8 is best.

        Impedance of a speaker will change with frequency. The better the speaker (generally) the less the nominal impedance will change in any given situation.


        What ohms are your speakers and your amp?


        ------------------
        szvook

        [This message has been edited by szvook (edited May 08, 2001).]
        Studio

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        • #5
          Originally posted by ADD:
          What is impedence?
          Impedance : (Z) Measured in ohms, it is the total opposition to the flow of current (I) offered by a circuit. Impedance consists of the vector sum of resistance (R) and reactance (X).


          Impedance Matching : Matching the output impedance of a source to the input impedance of a load to attain maximum power transfer.

          ... or what svook said is good.

          -----------------
          -~

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          • #6
            I'm pretty sure they are running at 4 ohms.
            I will check for sure tonight.

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            • #7
              Studio

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              • #8
                Zt = Z1 x Z2 / Z1 + Z2

                (8 x 8 = 64) / (8 + 8 = 16) = 4 ohms

                a shortcut is if you are using all the same impedance speakers, divide the imp. of 1 speaker by the total number of speakers.

                8 ohms / 2 speakers = 4 ohms

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                • #9
                  Svook, man....what the fu*k.

                  I'm hiring you as my sound guy when I'm famous.


                  I never understood any of that (and, being a drummer, never really needed to). I'm not sure I fully understand it now, but I'm glad I have more of a clue. Thanks.

                  BINARY

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                  • #10
                    Here's some more info on pa systems. Check the efficiency of your speaker cabinets. Generally, cabinets with two 15s and a horn are about 102/3 at 1w/m. That's pretty efficient. If your power amp says it is 1000 watts, it's probably rated at 1000 watts at 4 ohms bridged. This translates into about 350 watts per speaker cab at 4 ohms. Together with an efficiency of 102/3, this will give you adequate power for most small to medium places. Keep in mind that going through the passive crossovers in you speaker cabs will cost you approximately 10% of your power.

                    I agree with Sz, turn your amp up first . I almost always turn the power amps wide open. This will allow the transients/dynamics of the music to be fully reproduced at the power level you're using.

                    There are some things you can also check for to help with more clean power/volume. If your amp and speaker cabs have speakon connections, get two 14 gauge speaker cords. This will give an immediate boost in power and clarity, though not earth-shaking, assuming you are using normal 16 gauge 1/4" speaker cords. Make sure your speaker cords are the same length. Try to run the shortest speaker cords you can. Try not to run over 50' feet in each direction.

                    If you do as many of these as you can and start playing places where you need more clean power, beg, borrow, steal, but find a way to get a Mackie sub. It's extremely easy to interface into any pa system and it will give you loads of kick and bass that you didn't hear before, without the complexity of another amp, crossover, etc. You're big cabs will last many more years and they will be capable of getting seriously loud, cleanly.

                    Sorry this was so long. I tried to keep it short. Hope I didn't confuse you. You can e-mail me if you need more info. Hope it helped.

                    Jay
                    jg52

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                    • #11
                      Originally posted by BINARY:
                      Svook, man....what the fu*k.

                      I'm hiring you as my sound guy when I'm famous.


                      I never understood any of that (and, being a drummer, never really needed to). I'm not sure I fully understand it now, but I'm glad I have more of a clue. Thanks.

                      BINARY
                      Studio

                      Comment


                      • #12
                        Originally posted by szvook:
                        ... the flow of electricity (watts) coming from ...
                        Correct me if I'm wrong but, I thought the flow of electricity is known as current and current is measured in ampres.

                        -----------------------
                        -~

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                        • #13
                          Originally posted by Marc.:
                          Correct me if I'm wrong but, I thought the flow of electricity is known as current and current is measured in ampres.

                          Just lingo

                          ------------------
                          szvook
                          Studio

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                          • #14
                            Can I ask A Question?

                            How are you guys sending your stuff out to the p.a. and the amp?Are you using the outputs to send everything or are you using the headphones out to your amp?(monitor)
                            I have seen a couple of people in here that do that,And I didn't think you could.Am i missing something here?

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                            • #15
                              Studio

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