X-Treme Audio Monitor Line - Manual (Page 4)

MONITOR LINE
4.1 Amplification and constraints
Generally speaking, excessive power can sometimes damage the
transducer coil due to the production of high temperatures (high RMS
power for long periods). More rarely, it can also lead to damage to the
mechanical part of the cone (membrane and suspensions) as a result
of severe power peaks. Frequencies below the reflex tuning frequency
may cause excessive excursions within the cone (unnecessary given
the almost zero efficiency at these frequencies) and consequently also
damage. Thus, the use of external processors is always recommend-
ed, as they protect woofers and optimise their performance by trim-
ming the frequencies and limiting the signal. Like all X-Treme products,
the signal sent to the high frequency drivers in the Monitor Line has
passive protection by means of a specific filament device. The end
user must make sure a passive speaker is not supplied with signals
that can damage transducers. X-Treme Audio recommends the use of
XTDP processors for this purpose.
The objective of correctly sizing amplifiers and limiters is to achieve the
maximum performance of passive acoustic speakers without the risk
of potential damage. For maximum performance and maximum ex-
ploitation of the transducers at the signal peaks, a good rule of thumb
is to have a double-sized power amplification channel (“oversized”)
compared to the RMS power tolerated by the transducer. A limiter is
also needed to protect the transducer coil so the RMS power cannot
be exceeded for long periods. This is the job of the limiters contained
in the amplified versions of the Monitor Line and the X-Treme XTDP
external processors.
Generally, even if the amplifier power is lower than the transducer
power (undersized amplifier), this is no guarantee that the transducers
will not be damaged if the system is without a limiter. In actual fact,
even an undersized amplifier can “clip” the output signal where there
are high input signals: the result is the supply of higher power than the
amplifier’s nominal rating and the presence of delays marked by con-
tinuous voltages, particularly harmful for acoustic transducers.
X-Treme
Digital Technology Series amplifiers are recommended
for the amplification of XTMON12 and XTMON15 passive monitors
and have an internal limiter (anti clip) to prevent signal clipping, and
so are a good way to safeguard against transducer damage. Nev-
ertheless, as explained above, the use of oversized XTDT amplifiers
is recommended for maximum dynamic expression, limiting the input
by means of the limitation functions of the XTDP processor. The cor-
rect settings of the limiters and the size of XTDP processors, if used
with XTDT amplifiers, are included in the official presets that X-Treme
releases for these processors. If you use other amplifiers, X-Treme Au-
dio supplies a specially-designed Limiter Calculator spreadsheet with
the processor for estimating the limitation threshold. The power sup-
ported by the system of transducers within the speakers is 450W and
500W for the XTMON12 and the XTMON15 respectively. Therefore,
we recommend using amplifiers capable of delivering 750-1000 W of
power with a load of 8 Ohm or 1500-2000 Watt with a load of 4 Ohm
(such as X-Treme’s XTDT3800 or XTDT6000F amplifiers).
4.2 Connections between amplifiers and speakers
Each of the XTMON12 and XTMON15 passive monitor have two NL4
female Speakon connectors linked in parallel: one is used to receive
the power signal from the amplifier, the other to connect a second
speaker in parallel (thus halving the impedance “seen” by the ampli-
fier). The table shows the cables inside the cabinet between the NL4
Speakon connector and the transducers.
PIN 1- PIN 1+ PIN 2- PIN 2+
XTMON12
Full Range
Negative
Full Range
Positive
-- --
XTMON15
Full Range
Negative
Full Range
Positive
-- --
4.3 Power cables
It is extremely important to use power cables of the proper size. If
they are too long, they will result in considerable impedance and can
weaken the sound signal and distort the dumping factor of the am-
plifier-speaker. The following table gives the maximum recommended
lengths of power cables for different transducer impedances.
Maximum length
CSA conductor 4 ohm 8 ohm
1.0 mm 2 11 m 22 m
1.5 mm 2 17 m 34 m
2.0 mm 2 22 m 44 m
2.5 mm 2 29 m 58 m
4.0 mm 2 44 m 88 m
6.0 mm 2 66 m 132 m
5. GUIDELINES FOR USING ACTIVE MONITORS
XTMON12/A and XTMON15/A active monitors are dual amplified
internally with an 800+800W (@ 8 Ohm) switching technology ampli-
fier, located in a dedicated cavity to avoid the risk of mechanical stress
on the internal space housing the speaker. They also have a powerful
96 kHz/24 bit DSP (Digital Signal Processor) that fulfils the crossover
functions for the dual amplification with related limitations and allows
the end user to make additional adjustments to the sound. The rear
panel has an XLR balanced input with direct output link and Neutrik
PowerCon input for the supply and relative loop output. A LED indi-
cates the ON/OFF status, another one indicates when the IN signal
is present with a green light and a third, red LED indicates when the
limitation threshold has been reached. There are also 2 switches and
2 RJ45 female connectors: one for managing the internal presets and
the other for the network connection, as explained below.
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