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DESCRIPTION
TOA's SR-M1 and SR-M2 are actively processed, two way,
Stage/Floor Monitor Systems that feature high power handling,
bi-amplification, porting and the extremely rugged construction
necessary for reliable, portable use. Where every dB counts,
they maximize the audio information most critical to the performer
by addressing problems specific to floor monitors. Both systems
are designed to work with the AC-Ml Electronic Control Unit for
best performance. In one rack space each provides two
independent bi-amp channels, crossover phase alignment, driver
offset time correction, CD (constant directivity) horn EQ to correct
for losses inherent in CD horns, plus both LF and HF limiting.
DRIVERS:
Both systems are two-way, but the SR-M1 has a single
12" (30cm) woofer and the SRM2 has two 12" (30cm) woofers.
The 12" woofers, coupled with their 7.9" (200mm) magnets
(16,200 Gauss flux density), provide high efficiency and excellent
transient response for the lower frequencies. LF power handling
is 300 watts AES (M1) and 600 watts AES (M2)*.
Both systems use the same titanium diaphragm, high frequency
compression driver: the TOA HFD-652. It has a very smooth
frequency response and superb transient reproduction. Its RMS
power rating is a robust 80 watts*. The driver is coupled to a
40 x 40 degree CD horn crossed over at 1kHz. This means
highly efficient, focused HF coverage to cut through ambient
sound levels and reduce on-stage high frequency leakage into
other microphones.
FLOOR CORRECTION:
A unique system feature is the "FC" or "Floor Correction" function.
When slant type monitors operate on a floor, some of their sound
is reflected off the floor, acoustically interfering with their own
direct sound. This causes audible cancellations in the critical
midrange and thus a loss of this information to the performer.
TOA's engineers designed circuitry into the AC-Ml to correct for
this problem. This means performers will hear more of the critical
information they need at lower levels. Also, the smoothed
frequency response can result in higher gain before feedback.
DRIVER PROTECTION:
The driver protection in the AC-Ml is more than simple limiting.
For example, high pass filters for the LF sections provide
sub-sonic protection. Limiting is done by directly sensing
amplifier outputs. This means the limiters will only respond to
audio actually "seen" by the speakers. Separate limiters with
different processing are used to protect the HF and LF drivers.
INPUT CONNECTOR
Two Neutrik NL4MPR connectors are provided on both sides of
the speaker. They are internally parallel-connected, so either
may be used for loop-through connections,
Each connector contact is wired as shown in the right table.
CHARACTERISTIC DIAGRAMS (1/3 Octave Pink Noise)
at 2kHz of HIGH frequency)
SR-M1 (1/4W input/1m,
The limiting attack and release times are dependent on the
characteristics of the signal, for virtually transparent operation.
Typical LF limiters for bi-amped monitors simply reduce the entire
woofer output when limiting excessive lower frequency signals,
such as kick drum. Unfortunately, this reduces what the
performer needs to hear from the higher frequency portion of the
woofer's output. The AC-Ml is designed to correct this problem
by being able to limit lower frequencies to the woofer without
limiting the higher frequencies at the same time. Separate overall
LF limiting protects the latter range.
TIME/PHASE CORRECTION:
The frequency response is very smooth, particularly through the
crossover, because of the crossover phase, driver time offset and
frequency response processing provided by the AC-Ml. This
means you get a higher quality monitor mix with less prominent
ring modes, both of which minimize EQ adjustments. The time
domain processing also corrects factor which lead to improved
gain before feedback margins, and that EQ alone could not,
especially when microphones are in the speaker's proximity.
CONSTRUCTION:
The SR-M1/M2 enclosures are constructed of APITON plywood,
one of the densest, toughest plywoods made. (A more common
use is as the flooring for semi-trailers!) It eliminates undesirable
acoustic effects from cabinet resonances and flexing and it
makes the enclosures extremely rugged for road use. They are
finished in a tough, black epoxy paint with a heavy gauge,
removable, perforated steel grille to protect the drivers. Drivers
can be serviced from the front. No fewer than 8 machine screws
and "T" nuts are used to securely mount the woofers. On both
sides of the enclosure there is a recessed, heavy duty handle
and a Neutrik NL4MPR Speakon connector. The two Speakons
are wired in parallel for loop-through operation.
AC-M1:
The AC-Ml Electronic Control Unit has electronically balanced
inputs and outputs capable of +26dB (ref. OdB=0.775V).
The limiter sense inputs are bridging (10k ohm), allowing
connection to the amplifier outputs using standard shielded pair
audio cable. The front panel includes for each channel: FC Mode
In/Out; Input level; M1/M2 Select; LF/HF Sense Input and Limit
Lights. It has XLR audio and binding post sense connectors.
*Note At least 300 watts per HF and LF driver
damage due to clippIng with lower power amplifiers.
Applicable cable connector is Neutrik NL 4FC.
SR-M2 (1/4W input/1m, at 2kHz of HIGH frequency)
recommended to avoid possible speaker
IS
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