RCF TTL31-A, Owner'S Manual

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TTL55-A LOW SECTION
At low frequency vertical line array pattern control is reached by the constructive interference of the low frequency
sources on line array axis and destructive interference on line array off axis. This is true over a frequency range where
sources are omni-directional (for a 12inch below 400Hz) and its separation is comparable or lower than signal wave
length reproduced (TTL55-A vertical 12inch separation is 380mm this means that we should control vertical pattern with
constructive and destructive interference up to 1100Hz). Both these conditions are satisfies in the range where 12inch
works.
As the sound wave length decreases, more and more drivers, smaller in size and spaced more closely, are required to
maintain directivity. Practical line array systems act as line arrays only in the low and mid frequencies. For the high
frequencies, some other method must be founded to reach vertical directional characteristics that match those of
the low. The most practical method is to use wave guides coupled to the drivers. Rather than using constructive and
destructive interference, the waveguides achieve directionality by confining sound into a specified coverage pattern.
TTL55-A MID FREQUENCIES
TTL55-A mid frequencies are reproduced by one 10 inch dedicated
midrange coupled to dedicated unique 90°H by 15°V wave guide. It has
been designed with exponential expansion area for best low frequencies
coupling and to minimize distortion and back reflections. Wave guide has
been designed to coupled a single annular isophase wave front on 10
inch cone to a unique rectangular horn throat capable to create a single
isophase rectangular output. This wave guide is than coupled to other
horns wave guide to refine the narrow vertical coverage pattern and wide
horizontal coverage pattern. Final result show extremely narrow vertical
pattern control.
TTL55 MID-HIGH FREQUENCY WAVE GUIDES
TTL55 is loaded with three 2.5inch voice coil compression driver
designed with the minimum overall dimension actually on the pro
audio market 4inch (102mm!!). By the driver compact size it has
been possible to fit three of them in only 310mm with evident
benefit on tight directional vertical control over the frequencies. A
dedicated TTL55 high frequency wave guide couples three driver
circular (1.3inch diameter) isophase exit to the six rectangular output
apertures through six channels with exponential area expansions.
Each rectangular channel exit is capable to form a perfect isophase
wave front over the frequencies for best coupling to other adjacent
exits. From here another horns wave guide with constant directivity is
introduced for wide 90° horizontal pattern control. Finally, both mid
and high frequency wave guides are closely fitted on TTL55 for better
coupling on horizontal plane.