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One of the factors allowing it to cost so little was the clever adaptation of cardboard tubes, normally used as forms for pouring concrete pillars, for use as speaker enclosures. They have a number of advantages, other than low cost: their circular form helps eliminate resonance of the back wave within the enclosure; the material is rigid because of its shape, and is non-resonant due to its construction.

One of these is delta modulation. The Greek delta (which in its upper-case, block-letter form, looks like an equilateral triangle) is the mathematical symbol for the difference between two quantities; accordingly, in delta modulation, we record not the absolute value of a signal sample, but the difference between successive samples.