Handbook for Sound Engineers

616 Chapter 17

rear in a compression chamber. The E horn makes one

180 q fold that opens to the double mouths. The horn is

intended for use with additional mouth extensions and

in multiples for low-frequency coupling.

The W horn is another folded bass horn design. The

best-known example is the RCA theater horn, which

uses two 15 inch drivers. The W uses forward-facing

drivers, and the horn flare is designed as a W-shaped

double fold, expanding to twin mouths.

The Altec 31A uses a single 90q fold. This allows for

a short front-to-back dimension. Additionally, the driver

is mounted facing downward, making it rain and dust

resistant. This horn uses a 120º mouth and is used above

Figure 17-35. IMAX Proportional Point Source high fre-
quency horn. Courtesy James E. Mitchell & Associates.

Figure 17-36. 4 kHz isobar of the loudspeaker in Fig. 17-35.
Courtesy James E. Mitchell & Associates.

Figure 17-37. JBL studio monitor employing slant-plate-type
acoustic lens on a high-frequency component. Courtesy JBL.

Figure 17-38. Cross-sectional drawing of an exponential

folded horn.

Figure 17-39. University Cobraflex horn disassembled.

Courtesy Altec Lansing Corp.

20 "

24"