The LS5/5

The LS5/5 is a large three way monitor designed in 1967.

A 12 inch drive unit handles the low frequencies up to 400Hz. At this
point, an 8 inch midrange takes over before handing over to the 1 inch
soft dome tweeter at 3.5kHz. Overall, the frequency response is flat to
within ±2dB from 40Hz to 20kHz.

Straight away you’ll notice that the bass and midrange drivers are
mounted behind slots on the front panel. This feature is highly unusual
today, but it works to control the off-axis response of the drive units
which results in a smoother response through the crossover regions in
typical listening environments. Not surprisingly, we get a lot of
questions about this, so we have written an in-depth article
explaining how the slots work.

Naturally, this is a BBC-style “thinwall” cabinet, where the relatively
thin panels are mass-loaded to ensure that resonances are moved away from
the critical mid-range region. Rockwool provides air damping.
Hand-matched veneers are applied and finished to a very high standard. The
grille is carefully designed to minimise diffraction effects and is held
in place by concealed rare-earth magnets.