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JBL Control 28T 70V...100V...what does all that mean?

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  • JBL Control 28T 70V...100V...what does all that mean?

    Sorry I"m confused about this. Got one speaker on the cheap from some dude. Haven't got a chance to test it out yet. There's some knob u can set different clicks...but I dont' know what all that means. Could someone elucidate for me please?

  • #2
    It's a speaker intended for a distributed-line installation. What you see installed in buildings for Muzac, public address, etc. Here's a brief guide that'll explain it well:

    http://www.bhphotovideo.com/find/newsLetter/pro_audio_may07/pro_audio_understand_distributed_audio_may07.jsp

    You could possibly bypass the internal transformer and use it as a conventional 8 ohm system. Or rat out the guy who stole it (who has ONE d-l speaker for sale???) and use the reward money to get something you really want.
    "If you don't know where you are going, you might wind up someplace else" - Yogi Berra, 1925-2015

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    • #3
      i installed 4 of those in a room at work as part of a 70v system. they sound quite good if a little low mid heavy (read: slightly muddy but not bad). they get real loud!

      i dont know if they are useful in live sound, more of a meeting room or grocery store speaker imho (although the best grocery store speaker you would ever hear)
      band status - "its complicated"

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      • #4
        Let's just say I have a crown xls402 amp. Which setting would I need to make this work properly? Here's from the spec (I don't understand it)
        100 V Line:
        Tap 1 = 15 W, Tap 2 = 30 W
        Tap 3 = 60 W, Tap 4 is not used
        70 V Line:
        Tap 1 = 7.5 W, Tap 2 =15 W
        Tap 3 = 30 W, Tap 4 = 60 W

        Here is the amp specs: 570W/ch @ 2 ohms, 400W @ 4 ohms, 260W @ 8 ohms, 800W bridge mono @ 8 ohms, 1,140W bridge mono @ 4 ohms

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        • #5
          Tap 4 is probably the cloaest match, when operated from the amp in stereo mode. Note that the real power handling of the speaker is quiet low AND you MUST high pass the signal at about 50-70Hz or you may saturate the transformer. You will need to look up[ the application specs on this specific speaker.

          You sure it's not hot? That's an unusual way to get a speaker like this.
          -------------------------------------------------------------------------------------------------------------------------------------------------------------------
          Former product development engineer: Genz Benz, a KMC Music/FMIC/JAM Industries Company, continuing factory level product support and service for Genz Benz

          Currently product development engineer: Mesa Boogie

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          • #6
            OP, here is a link to the product page for this speaker: http://www.jblpro.com/catalog/general/Product.aspx?PId=186&MId=2

            Like CraigV said, this particular speaker is designed for a distributed line situation using specialty 70/100V amp systems, not for general-purpose PA use off a conventional amplifier. Trying to drive one off an XLS402 in any fashion is likely to result in fried gear.
            Chief fader ape, wire monkey, mic macaque, and speaker chimp.

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            • #7
              Will a regular home theater receiver with 70 watts rms be ok to drive this speaker?

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              • #8
                Looks to me like you're confusing watts and volts. You should have asked here, before buying that speaker.
                Veni, Vidi, Velcro;

                (I came, I saw, I stuck around)

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                • #9
                  here is a pic of two of the four i have installed in this room. they are hooked to a crown 280A which is a 70V amp. in this room they are quite loud. the room is setup for layback and a live mic in the room, but nothing more and its quite effective at this.

                  i would never ever run a band though them.
                  band status - "its complicated"

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                  • #10
                    OP, here is a link to the product page for this speaker: http://www.jblpro.com/catalog/general/Product.aspx?PId=186&MId=2

                    Like CraigV said, this particular speaker is designed for a distributed line situation using specialty 70/100V amp systems, not for general-purpose PA use off a conventional amplifier. Trying to drive one off an XLS402 in any fashion is likely to result in fried gear.


                    Won't blow anything up, but you need to understand how 70 volt distribution works. At 70 volts, the speaker will dray 60 watts on the tap I suggested. The speaker acts like 64 ohms and the amp that the OP has will deliver ~30 watts into 64 ohms. Bridging would result in ~90 volts (rough guess) and that might be ok but not for starters.
                    -------------------------------------------------------------------------------------------------------------------------------------------------------------------
                    Former product development engineer: Genz Benz, a KMC Music/FMIC/JAM Industries Company, continuing factory level product support and service for Genz Benz

                    Currently product development engineer: Mesa Boogie

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