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INTRODUCTION
Thank you for choosing LOUD Technologies’ Mackie
active sound reinforcement loudspeakers.
The SRM450v2 is a redesigned version of our
popular SRM450 active loudspeaker. With its newly
designed Class-D Fast-Recovery amplifiers, high-output
compression driver, and 12" woofer, it produces an even
smoother sound than the original. SRM means Sound
Reinforcement Monitor, and the SRM450v2 truly produces a
studio quality sound in a sound reinforcement speaker.
Our design goal was to build a sound reinforcement
speaker with:
1. High precision, high output, and accurate playback.
2. Very wide, smooth dispersion of mid and high
frequencies.
3. Ergonomically correct physical design for easy transport
and set up.
Through the combined resources of our top-notch
mechanical and analog engineers, and our experienced
transducer engineers at EAW, we were able to achieve our
design goals in every aspect. The result is a sound
reinforcement system equally at home in a concert setting, in
the studio, impromptu concerts on the studio roof, in the
cinema, or in a home theater.
The Transducers
The SRM450v2 active speakers feature a 12-inch high-
power low-frequency woofer with a 3-inch voice coil and
a 1.75-inch titanium diaphragm
high-output compression
driver. This high-frequency driver is mounted on an
acoustically non-resonant
exponential waveguide, providing
a wide, controlled dispersion and precise reproduction of
the critical upper mid-range and high frequencies. The
result is an unbelievably smooth off-axis response that
allows everyone
in the audience to experience the same
high-resolution audio no matter where they are seated.
The Power Amplifiers
To power these beauties, each SRM450v2 includes two
of
our acclaimed FR Series “Fast Recovery” power amplifiers. In
addition, the low-frequency amplifier uses a Class D
design
for improved efficiency and cleaner power. Our exclusive
designs use low negative feedback, yet allow the amplifiers
to maintain low distortion and stability and to quickly
recover when driven into clipping.
The amplifiers include the following features:
• Thelow-frequencyamplierproducesupto540watts
peak (300 continuous) before clipping.
• Thehigh-frequencyamplierproducesupto150watts
peak (100 continuous) before clipping.
•
Each amplifier has its own compressor circuit that acts
when the input signal is large enough to cause clipping,
distortion and excessive voice coil heat. The compressor
will automatically decrease the input signal to a safe
level. The compressor in the low-frequency amp works
independently from that in the high-frequency amp.
• Thelow-frequencyampusesaservofeedbackloop
which senses the current flowing in the woofer coil. This
controls the low-frequency response and maintains low
distortion at high output levels.
• Thelow-frequencyamplieralsohasasweepinglter.
This will automatically move the low cut-off frequency up
or down depending on the amplifier output. For example,
if the amplifier is below clipping, the low-frequency cut-
off point is 55 Hz. As it approaches clipping,
this shifts up
smoothly to 120 Hz, providing more power reserves and
less distortion before clipping. This happens quickly
and continuously, protecting the amplifier and the
woofer and reducing any noticeable distortion.
Warning: Although the amplifiers have
these protection circuits, you must still
make sure the PEAK light is not blinking
continuously. If it is, turn down your
mixer faders, or preamplifier gain, or
turn down the SRM450v2 LEVEL
control.
The Crossover
The built-in electronic crossover is a 24 dB/octave
Linkwitz-Riley design. Although more expensive than other
crossover designs, the benefits provided by the Linkwitz-
Riley design have been well documented. These benefits
include:
• Absolutelyatfrequencyresponsethroughoutthe
bandpass, without the characteristic ripple near the
crossover point exhibited by other designs.
• Thesharp24dBperoctaveroll-offoftheltersensures
that the transducers aren’t reproducing frequencies
outside of their capabilities.
• Theacousticsumofthetwodriverresponsesisunity
at the crossover frequency, resulting in perfect power
response.
• Ourheroicengineershaveworkedcarefullyto
ensure that the SRM450v2 also provides perfect phase
response. This diligence has yielded phenomenal
accuracy, even if you are standing 20 feet away.