appendix
Systems building with the MI 120
Stereo Integrated Amplifier, the MP 100
Stereo Preamplifier and the MA 120 or
MA 240 Stereo Power Amplifiers
The MI 120 was designed to integrate into
a wide range of hi-fi systems and fulfil the
requirements of most listeners. However, we
realise that many people will want to expand
their system, either to enhance the sound
quality even further, or to extend the benefits
of their Myryad system into other rooms.
The MA 120 Power Amplifier was developed
to meet these needs with a minimum of
additional wiring and complexity.
For even higher quality sound and greater
flexibility the MP 100 preamplifier can be
used with one or more MA 120 or MA 240
power amplifiers
This paper describes how multi-amplifier
systems can be built using:
•the MI 120 plus one MA 120 in
“Bi-Amplifier" systems
•the MI 120 plus two MA 120s in
“Tri-Amplifier” systems (with
suitable loudspeakers).
•the MP 100 Preamplifier plus one or
more MA 120s or MA 240s in Bi-Amp
or Tri-Amp systems.
It also shows how the MI 120 or the MP 100
can feed one or more MA 120 or MA 240
Power Amplifiers for driving loudspeakers
in other rooms.
The MI 120 plus MA 120 in
“Bi-Amplified” Systems
Many loudspeakers today are produced with
two sets of terminals to allow “Bi-Wiring”. In
this configuration two sets of speaker cables
are used to connect from one integrated
amplifier (e.g. the MI 120) to the loudspeakers:
the left channel of the amplifier is wired by
one cable to the left speaker BASS terminals
and also by a second cable to the left speaker
TREBLE terminals – and the right channel is
wired in a similar way. This arrangement is
shown in Figure 1. Improved sound quality
can result because the signal losses in the
loudspeaker cables caused by the bass section
cannot affect the treble – and vice versa.
The so called “Bi-Amplifier” mode of operation
takes this principle one step further. Two
power amplifier channels are used for each
loudspeaker and each is wired by its own
speaker cable to the relevant speaker section
(Bass or Treble). Bi-Amplified operation with
the MI 120 and MA 120 is shown in Figure 2.
The MI 120 “BI-AMP” output level and the
MA 120's gain are set such that the MA
120 output voltage is identical to the MI 120
output so that the bass/treble balance of
the loudspeaker is unchanged when it is
bi-amplified.
In the bi-amplifier configuration both the MI
120 and the MA 120 carry the full bandwidth
audio signal. However, the MI 120 only has
to deliver output at low frequencies so the
amplifier has a very easy task in reproducing
the signal accurately. Conversely, the MA 120,
as it is only loaded by the speakers' treble
sections, only drives significant output
current at high frequencies and has to deliver
almost no current on bass notes. This allows
the MA 120 amplifier to operate with
improved fidelity in delivering the critical
signal transients as its power supply is only
very lightly loaded.
In short, by restricting the bass power
delivery to the MI 120 and the treble to the
MA 120, interactions between bass and treble
within each amplifier are very much reduced.
The end result is a more transparent sound
with more power and punch in the bass and
a cleaner, sweeter top end. An additional
advantage incurred with bi-amplification
is that the total power consumed by the
loudspeaker is now being drawn from two
power supplies, with two massive toroidal
transformers. The result is an increase
in dynamics and peak power output –
particularly with low impedance
loudspeakers.
Alternatively the MI 120 may be used to drive
the bass and the MA 120 the treble. This
configuration will offer a slightly differently
improved sound, which may be preferred in
some systems.
Using the MA 240 with an MI 120 or
mixed MA 120s and MA 240s with an
MP 100 in Bi-Amp or Tri-Amp systems
In the system described above the higher-
powered higher quality MA 240 may be
substituted for the MA 120. The MA 240 has
the same gain (i.e. the same input signal
required for a specific output power) so the
system bass/treble balance will be the same,
whichever power amplifier is used. The MA
240 offers a much higher sound quality than
the MA 120 and can deliver considerably
more output current, so it is likely to produce
significantly better sound in such a bi-amp
system. However, it will not result in any
substantial increase in maximum sound
level as the MA 240 will only be operating
at 60 watts (half its maximum power) when
the MI 120 is fully driven to its maximum
output of 60 watts. These same points apply
to mixing MA 120s and MA 240s in any
bi-amp, tri-amp or multi-room system with
the MI 120 or MP 100, such as those
described below.
The MI 120 plus two MA 120s in
“Tri-Amplified” Systems
There is a growing number of three and four-
way loudspeaker systems which are provided
with three sets of terminals allowing tri-
wiring or tri-amplifying, with separate feeds
for bass, mid and treble frequencies.
The MA 120 is fitted with a pair of Line
Outputs, wired in parallel with the Line
Inputs, which allow a second MA 120 to be
wired in parallel to the first – in “daisy-chain”
fashion. This configuration is depicted in
Figure 3 which shows how loudspeakers can
be “Tri-Amplified” using one MI 120 and two
MA 120s. The MI 120 drives the bass sections,
the first MA 120 the mid and the second
MA 120 drives the treble so that the overall
performance is optimised in a similar way to
that described for bi-amplifying.
The MI 120 or MP 100 with one or
more MA 120s or MA 240s in Multi-
Room systems
Once a high quality audio system is installed
in your main listening room, you may find
you want to the same sound quality in
another room (or rooms). Installing separate
sound systems in each room is one solution,
but the cost and complexity is high – and you
will always find the CD or record you want to
play is in the other room!
Multi-room Hi-Fi installations are becoming
ever more popular and many offer a great
deal of flexibility – but at a considerable
price. Myryad Systems offer a simple and
inexpensive multi-room set-up using the
MI 120 integrated amplifier, or MP 100
Preamplifier, together with one or more
MA 120 or MA 240 power amplifiers. (In
all instances below, wherever MA 120 is
mentioned the MA 240 could be substituted,
but the MA 240 is generally better suited to
MP 100 based systems.)
The MI 120 is situated in your main listening
room in your normal Hi-Fi system. Its BI-
AMP output is fed to the Line Input of an
MA 120 whose Line Output, in turn, is
9
8
trouble-shooting
guide
Some of the most common problems
No sound:
•Power turned off or system in standby
mode. Check that the LED in the
STANDBY button is green.
•The input connection is loose or missing.
Check that the connection is secure.
•Protection relay has operated because of
a short circuit loudspeaker wire or
amplifier overheating. Carefully check all
wiring after switching the amplifier
POWER OFF to allow it to cool.
•The fuse in the power cord inlet has
failed. Unplug the power cord from both
the wall socket and the amplifier and
pull out the small receptacle below the
power cord inlet. Two fuses should be
visible. The further fuse is the operative
one and should be checked. If it has
failed, replace it with the nearer (spare)
fuse. If this too fails, then return the
amplifier to your dealer for service.
•UK version only: The fuse in the mains
plug has failed. Check and replace
if necessary.
Sound in one channel only:
•Loudspeaker cable pulled loose. Check
all connections, both at the loudspeakers
and amplifier.
•Interconnect cable pulled loose or
making poor contact. Check and,
if necessary, un-plug and re-plug all
relevant cables.
Amplifier fails to respond to My Link remote
commands (from e.g. MP 100 Preamplifier):
•My-Link cable is loose or not connected.
Check connections on all linked units.
Loud buzz or hum:
•Interconnect cable pulled partially out
of its socket.
•Defective interconnect cable.
Incorrect operation – some functions
not working:
•Control processor latched. Switch off
POWER on rear panel and wait for about
one minute. Then switch POWER on.
Normal operation should resume.
English MA 120-240 ok 29/1/01 10:06 am Page 8
