HHB comm CIRCLE STUDIO MONITORS - Manual (Page 12)

Circle 5 & Circle 3 - Passive
Choosing an amplifier to match your speakers and
application is important. The passive HHB Circle 5
requires connection to a power amplifier with a
suggested output between 50 and 200 Watts
RMS, and the Circle 3 should be powered by an
amplifier with an output of 30 to 100 Watts.
Connection is made via a pair of binding posts on
the rear of the loudspeaker. Take care to ensure
that the positive (red +) terminal on the
loudspeaker is connected to the positive
(red +) terminal on the amplifier, and that the
negative (black –) terminal on the speaker is
connected to the negative (black –) terminal on the
amplifier. Connecting one of the loudspeakers out
of phase will result in dramatic loss of low
frequency signals and an incoherent spatial image.
Always use good quality medium or heavy-duty
speaker cable, not thin ‘bell’ wire. The main
function of a speaker cable is to transfer the
maximum amount of current with the minimum
amount of distortion. It is therefore preferable to
have a cable with a wide cross-sectional area, since
this will reduce the electrical resistance. If the
cable is too thin, the resistance rises and heating
may occur. Where possible, try to use the same
length of cable for each speaker.
Circle 5 & Circle 3 – Active
Audio connection to the active HHB Circle 5 and
Circle 3 is via balanced XLR or unbalanced RCA
phono. A switch selects the desired audio input.
The active Circle 5 and 3 should be connected to a
suitable mains power supply via an IEC connector.
Power should be switched off when connecting or
disconnecting any signal to or from the
loudspeakers, or when changing the position of the
selector switch, since the loudspeakers and
internal amplifiers may be damaged. When audio
cable runs are long – about ten metres or more
(approximately thirty feet) – or there is
electromagnetic interference in the vicinity of the
cable (from a motor, for instance), it is advisable to
use balanced XLR cables so as to avoid any induced
noise. The master volume control on the active
Circle 5 and 3 acts as a sensitivity control. When
at its highest, the input is at maximum sensitivity
and the amplifiers will be fully driven by an input of
1V. The best way to set this correctly is to ensure
that the monitor output of the mixing desk or other
equipment that is driving the speakers, is set to
produce a peak output of 1V. The master volume
control also allows for balancing between
loudspeakers; ideal for use in a surround sound
environment.
Circle 1 Active Sub-Woofer
The HHB Circle 1 is an active sub-woofer,
containing built-in amplification and active
crossover circuitry, designed especially for use with
Circle 5 and Circle 3 loudspeakers in a surround
sound setup. Its flexible input and output
capabilities allow quick and simple connection to
the other loudspeakers. The HHB Circle 1
sub-woofer has three distinct modes of operation,
set by a switch on the rear panel – these modes
are ‘5.1’, ‘B’ and ‘C’. The system is designed for
decoded or discreet 5.1 reproduction but also
caters for earlier formats of surround sound or
bass enhancement in a conventional stereo system.
Using the HHB Circle 1 in ‘5.1 mode’ there are two
connection methods in a surround sound system.
With method 1, the separate sub input allows
direct connection from a dedicated line level low
frequency effects (or sub) channel on a surround
sound decoder, mixing desk, or a multitrack
recorder, Using this method, only one physical
connection is made to the sub-woofer – the other
five loudspeakers are sent their own discrete
signals directly from the mixing desk, etc.
In the second connection, method 2, all the monitor
signal outputs (normally left, centre, right, left
surround and right surround) are connected to the
inputs on the HHB Circle 1, and the outputs are
fed to the loudspeakers. This method filters the low
frequencies (below 120Hz) from the loudspeaker
feeds. The sub-woofer is always driven from the
SUB input – it receives no low frequency
information from the other five inputs. This
connection method is widely used, since by
removing the extreme low frequencies, the five
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LOUDSPEAKER CONNECTION
Circle Studio Monitors
5.1 mode - method 1
6
Figure
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