Macro-Tech 24x6 Reference Manual - page 19
Page 19
Macro-Tech 24x6 & 36x12 Power Amplifiers
ing the drive level. Second,
ODEP data is fed to the
back panel
P.I.P. connector so advanced P.I.P. mod-
ules like the
IQ–P.I.P.–SMT can use it to monitor and
control the amplifier.
With
ODEP, the show keeps going because you get
the maximum power with the maximum protection.
4.3.2 Standby Mode
At the heart of the protection systems is the standby
mode which removes power from the high-voltage sup-
plies to protect the amplifier and connected loads. The
standby mode can be identified using the indicator
table in Figure 4.2.
Standby mode can be activated in several situations.
First, if dangerous subsonic frequencies or direct cur-
rent (DC) is detected in the amplifier’s output, the unit
will activate its
DC/low-frequency protection
circuitry
and put the affected channels in standby. This protects
the loads and prevent oscillations. The unit resumes
normal operation as soon as the amplifier no longer
detects dangerous low frequency or DC output. Al-
though it is extremely unlikely that you will ever activate
the amplifier’s DC/low-frequency protection system,
improper source materials such as subsonic square
waves or input overloads that result in excessively
clipped input signals can activate this system.
The amplifier’s
fault protection
system will put an am-
plifier channel in standby mode in rare situations where
heavy common-mode current is detected in the
channel’s output. The amplifier should never output
heavy common-mode current unless its circuitry is
damaged in some way, and putting a channel in
standby mode helps to prevent further damage.
The amplifier’s
transformer thermal protection
cir-
cuitry is activated in very unusual circumstances where
the unit’s transformer temperature rises to unsafe lev-
els. Under these abnormal conditions, the amplifier will
put the channel of the affected transformer in standby
mode. The amplifier will return to normal operation af-
ter the transformer cools to a safe temperature. (For
more information on transformer thermal protection, re-
fer to the following section.)
4.3.3 Transformer Thermal Protection
All
Macro-Tech amplifiers have transformer thermal
protection. It protects the power supplies from dam-
age under the rare conditions of transformer tempera-
tures rising too high. A thermal switch embedded in
each transformer removes power to the channel if there
is excessive heat. The switch automatically resets
when the transformer cools to a safe temperature.
It is very unlikely that you will ever see a
Macro-Tech
amplifier activate transformer thermal protection as
long as it is operated within rated conditions (see Sec-
tion 6,
Specifications). One reason is that ODEP keeps
the amplifier working under very severe conditions.
Even so, higher than rated output levels, excessively
low impedance loads and unreasonably high input sig-
nals can generate more heat in the transformer than in
the output devices. These conditions can overheat the
transformer and activate its protection system.
Macro-Tech amplifiers are designed to keep working
under conditions where other amplifiers would fail. But
even when its limits are exceeded, it will still protect
itself—and your investment—from damage.
4.3.4 Circuit Breakers
The power supplies are protected by circuit breakers.
With rated loads and output levels, the circuit breakers
should only shut down the amplifier in the rare instance
of a catastrophic failure. Other protection systems like
ODEP keep the amplifier operational under most other
severe conditions. The circuit breakers can also shut
down the amplifier in cases where extremely low-im-
pedance loads and high output levels result in current
draw that exceeds their rating. Again, this should only
be possible when operating
outside rated conditions,
like when the amplifier is used to drive a 1-ohm load in
Stereo mode, or when a signal overloads the input and
is clipped severely.
Macro-Tech amplifiers do not trip their breakers unless
something is wrong. If a breaker trips, try to identify
and correct the problem before resetting the breakers
with the back panel
Reset switches
. If the problem
persists, refer the unit to a qualified technician.
4.4 Controls
The
Enable switch
is located on the front panel so you
can easily turn the amplifier on or off. If you ever need
to make any wiring or installation changes don’t forget
to disconnect the power cord. The six steps listed next
should be followed whenever you turn on the amplifier:
1. Turn down the level of your audio source. For
example, set your master mixer’s volume to –
∞
.
2. Turn down the level controls of the amplifier (if they
are not already down).
3. Turn on the Enable switch. The Enable indicator
beside the switch should glow. During the four
second mute delay which immediately follows, the
Signal/
IOC indicators will flash unpredictably and
the
ODEP LEDs will stay off. After the mute delay,
the
ODEP indicators should come on with full