Turbosound LMS-D6 - Manual (Page 43)

user manual
TA-890
TA-890 user manual
Page 43
Bessel Array
In the above example five bass bins are again spaced ¼ of a wavelength apart. However in
this example the outside two are reduced in gain by 3dB. The inside pair are out of phase
while the middle unit is in phase.
This is known as a Bessel array, and will create the smoothest horizontal coverage possible at
a given frequency.
Whilst this approach works well it is important to balance this against the practicality of
setting up three or more discreetly processed LF bands within the system architecture.
General observations of long lines of bass
Aspect bass enclosures cross over at 100Hz into the mid/high box. This means that a lot of
the punch from a kick drum is provided by the 2 x 15” bass enclosure. If the bass bins are
deployed in a configuration based on a long line across the front of the stage it is important
to ensure that the top of the stack is above head height (which may not be possible due to
sight lines restrictions) as the audience will absorb some of the attack provided by the 2 x15”
enclosure.
With extremely long lines of bass the relationship between the flown mid/high clusters and
the line of bass can create a problem around the crossover point, as the time alignment
between the enclosures can only be correct in a limited coverage area.
When using both the 2 x 15” bass bin and 2 x 18” ultrasub it is desirable to try and keep the
enclosures in the same plane as each other to avoid time alignment and cancellation
problems through the crossover region.