Half-Space Measurements

Comparisons of the different models with each other and commercial cabs.
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Bill Fitzmaurice
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Half-Space Measurements

#1 Post by Bill Fitzmaurice » Wed Jul 14, 2010 3:43 pm

Half-space measurements are the industry standard, as they are the most easily accomplished. While getting them right indoors requires an anechoic chamber, they can be performed outdoors with high accuracy and no special sound and echo-proofed room. Unless otherwise specified all our measurements are half-space, referenced to 2.83v at 1 meter.

The problem with half-space charts is that they don't reflect what the speaker will do indoors. This is especially critical with subs in general, and horn loaded subs in particular, where boundary loading is part and parcel of the speaker design. To illustrate, this is a modeled 1 watt chart of a single horn loaded sub in half-space, ie., outdoors on the ground:

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The rolloff in the low end doesn't look all that good. But take that same cab indoors and put it in a corner and this is the result, compared on the trace to outdoors:

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Corners aren't always available, but walls are. This chart shows four cabs wall loaded, referenced to 1 watt, compared to one cab outdoors:
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But if you can corner load multiple cabs do so. The same four cabs, 1 watt, now in a corner:
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If you do gigs outdoors and can't use a wall response still flattens with more cabs. You will get nearly the same response outdoors with no wall as you do indoors with a wall by doubling the number of cabs.

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