Line Array Gain Taper (Breaking the Line II)

After Bob Gardam’s comment on Breaking the Line I decided to give a quick go of the hypothetical scenario I had proposed in my reply:

12 boxes,  6 @ 2 degrees @ 0 dB, 3 @ 4 degrees @ -2 dB, 3 @ 8 degrees @ -4 dB.

I made screen dumps of 3 scenarios:

1) 0,-2, -4 dB taper – the system as it would be if operated below limiting

2) 0, 0, -2 dB taper – the system as it would be if the top section only was limiting

3) 0, 0, 0 dB taper – the system as it would be if the whole system was limiting – or if there was no gain tapering

As expected the compression reshapes the HF range most noticeably. The honed agular shape – longer throw for the uppers – becomes rounded so that the relative level in the near areas goes up.  This is most easily seen in the 4 kHz response because there is minimal fingering, but is also present in the 8 k Hz response.

The 1 kHz response carries on the trend in a similar – yet reduced fashion. Notice that the main frontal lobe is barely affected. Waht you see is an increasing bulge in the underside heading toward the near seats.

The 250 Hz response requires a very careful look to spot the changes. Two things are happening. As the taper is reduces by compression the additional coupling of the lower boxes steers the main lobe downward by a whopping 1 degree.  Not exactly a game changer. People who can hear that in their system should check out the products of Acoustic Revive.  The other change is that the beam has narrowed very slightly. This can be seen by the markings I made of the original shape. The mechanism causing the narrowing is the same as the downwaqrd beam steer – increased summation causes both.

So here is your choice – loud HF in the front ALL the time, or only when we drive it limiting. Bear in mind also that the limiting simulated here is a brick wall. Actual limiters will be more forgiving so results in the field would be somewhat LESS than that pictured.

6o6

Comments

  1. Thanks for remembering all of us that a line array is NOT one single large box but a fragile combination of many individual boxes. No matter what the PR guys say.

    • Thanks Harald for your comment. The beauty of the line array is that we can precisely sculpt the interactions into the shape we need. Indeed, as you are saying, at the same time our to shape comes from extremely high levels of overlap interaction, over extended frequency ranges.
      A VERY SENSITIVE beast, but when it’s tamed, it can do some great tricks!

      6o6

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