Announcement

Collapse
No announcement yet.

Polyswitch for line-array

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Polyswitch for line-array

    Hi all,


    I would like to build in some protection to a line array I'm building. The line array will consist of 12 Neo3 PDRW tweeters in series/parallel and I want to confirm if my calculations for a polyswitch are correct.

    Here's what the setup will be like:
    Active x-over >>> Amp >>> Polyswitch >>> Line array (5.3 ohms amp load)

    The Neo3 has a rated RMS of 20 Watts, and I want the polyswitch tripping ampere value to be around those 20 Watts.


    Assumptions:
    - 20 x 12 neo3 = 240 Watt RMS for the whole array
    - The amp will see a load of about 5.3 ohm with the series/parallel configuration I'm using


    So my calculation goes as follows:
    Step 1. Sqrt(240) = 15,49
    Step 2. 15,49 x 2 = 31
    Step 3. 31 / 5,3 ohm = 5,85 ampere
    So the tripping value would have to be around 6 ampere for my purpose.

    Are my assumptions and calculations correct here? Is using the RMS value of the tweeter a smart thing or do you recommend a lower / higher value?

  • #2
    Re: Polyswitch for line-array

    Originally posted by Zippy2000 View Post

    Are my assumptions and calculations correct here? Is using the RMS value of the tweeter a smart thing or do you recommend a lower / higher value?
    It depends on how both the switch and tweeters were rated, and it gets quite complicated, due to the 3dB lowering of power density with each octave increase of the lower limit of the bandwidth. It's so complicated as to make attempting to use either power or current limiting an almost fruitless exercise. That's why pro-sound applications use limiters that brickwall the amp's voltage swing. Twelve of those should get stupid loud without any threat of damage anyway.
    www.billfitzmaurice.com
    www.billfitzmaurice.info/forum

    Comment


    • #3
      Re: Polyswitch for line-array

      Zippy: Out of curiousity have you heard a system that had a polyswitch in the tweeter circuit?
      I realize it is subjective ( and could launch responses of different opinion ), but to my ears they denegrate the sound.
      "Not a Speaker Designer - Not even on the Internet"
      “Pride is your greatest enemy, humility is your greatest friend.”
      "If the freedom of speech is taken away, then dumb and silent we may be led, like sheep to the slaughter."

      Comment


      • #4
        Re: Polyswitch for line-array

        P=(i^2)*r
        I=(p/r)^0.5
        P=240
        R=5.3

        I=6.729a

        Comment


        • #5
          Re: Polyswitch for line-array

          Originally posted by billfitzmaurice View Post
          Twelve of those should get stupid loud without any threat of damage anyway.
          You're right about that

          I was more thinking in the line of pop and click protection, but I guess a polyswitch works like a slow blow fuse and will not help much anyway...


          Originally posted by Sydney View Post
          Zippy: Out of curiousity have you heard a system that had a polyswitch in the tweeter circuit?
          I realize it is subjective ( and could launch responses of different opinion ), but to my ears they denegrate the sound.
          Not that I am aware of. There are many opinions going around on different forums. Some say it doesn't matter, some say it does. I guess it will definitely make a difference if you interupt your high grade speaker cable with a simple polyswitch... Need to try it myself first though.

          Comment


          • #6
            Re: Polyswitch for line-array

            There are many opinions going around on different forums. Some say it doesn't matter, some say it does.
            You are right there.
            I've heard it argued adamantly that a fuse ( another current based device ) doesn't work.
            However, as voltage is increased, so is current - so a fuse is sized with that in mind.
            I've had the same amplifier(s) since 1982 and they have speaker fuses; while I've popped a few over the years, I've never blown a driver. One amplifier drives the tweeters directly
            Personally I would use the same sizing guidelines as fuses.
            "Not a Speaker Designer - Not even on the Internet"
            “Pride is your greatest enemy, humility is your greatest friend.”
            "If the freedom of speech is taken away, then dumb and silent we may be led, like sheep to the slaughter."

            Comment

            Working...
            X