Technical Overview

TWIN LF DRIVERS
Two identical 8”/8Ωaluminium-alloy diaphragm LF drivers
deliver a -3 dB point of 20 Hz with a usable response
down to 15 Hz at -6 dB. These units are user-replaceable.
CLOSED-LOOP LF CONTROL
To obtain the ultimate in low frequency response for the
cabinet size, closed-loop feedback is used to control the
LF drivers. This system uses an accelerometer mounted on
each diaphragm. These feed motion-related signals back
to circuits that ensure each 500 W power amplifier
produces exactly the right drive current under all
conditions, resulting in a highly accurate and extended low
frequency response.
3-K DRIVER ARRAY TECHNOLOGY
An innovative positioning technique is used on the 328A
whereby the midrange, tweeter and super-tweeter drivers
are mounted on the 3-K driver array (patent applied for) in
front of an acoustically-shaped reflection cavity extending
below the baffle plane. This provides unmatched signal
reproduction accuracy in the mid and high frequency
ranges, together with excellent stereo imaging and
dispersion. The 3-K driver array is user-replaceable as a
unit.
AMPLIFIERS AND POWER SUPPLIES
All five amplifiers are conservatively rated for delivering
sufficient power to the drivers to achieve the rated
maximum acoustic output. The power supply high voltage
rails track the average output for maximum efficiency and
minimum heat generation.
CABINET DESIGN
The closed-cabinet design is low profile, flat fronted with
curved sides. Carrying handles on the sides make for easy
handling. The back panel comprises two large aluminium
heatsinks for the power amplifiers with a central plate
carrying the controls and connectors. Ventilation slots for
the amplifiers and power supplies run across the top of
the cabinet at the rear.
The sides and top of the cabinet are formed from painted
Hornflex™, an MDF-based material. This innovative
material makes possible the curved surfaces of the 328A
that greatly reduce internal standing wave patterns, and
hence practically eliminate colouration.
Four adhesive-backed rubber feet are supplied for
positioning on the base of the unit as required.
GRAPHS
10 Hz 20 50 100 200 500 1K 2 5 10 20 50
10
20
30
40
50
60
70
80
90
100
110
10 Hz 20 50 100 200 500 1K 2 5 10 20 50
10
20
30
40
50
60
70
80
90
100
110
Flat
Flat
Bass roll-on 50 Hz
Bass roll-on 100 Hz
Treble -1.5 dB
Treble +1.5 dB
Anechoic response showing effect of Treble Shelf
and Bass Roll-on equalisation features
Anechoic response (flat)
2
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