Scoop: Short Horn Channel with a Side Effect

In a scoop, the driver radiates through a short, curved sound channel. The curve is often bent from several glued layers of thin plywood – for the Super Scooper 18 from six layers of 3 mm plywood. The drawings of the Super Scoopers call the enclosures “rear loaded horn”.

Below the usable range, the driver is barely loaded by the enclosure any more. Rog Mogale explicitly writes about his Super Scoopers: use a high-pass around 30 Hz. Without a high-pass, the driver risks making excessive excursions at low frequencies.

By his own account, Rog Mogale does not like scoops, although he has designed two himself. His reasoning in the FAQ:

• The front and rear of the cone radiate in antiphase. This creates a dip in the frequency response, with 15- and 18-inch scoops typically between 70 and 90 Hz – exactly where you feel the kick.
• The dip is usually 3 to 6 dB deep. With 21-inch scoops it lies lower, around 50 to 60 Hz, and becomes weaker with more enclosures.
• He prefers folded horns because they do not have this dip.

This is the assessment of a single designer, not a measurement.

• Super Scooper 18 – for the PD 1850, single 38 Hz, in groups of four 30 Hz lower cut-off frequency
• Super Scooper 21 – for the PD 2150, single 35 Hz, in groups of four 28 Hz