Amplifier Research 701R Manual del usuario - Página 4
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Imprimir páginaMASTER SECTION — FRONT PANEL
As the name implies, the master section of the 701R Mixer
contains all of the controls for the respective mixing busses
and supplementary controls to allow other special functions
to be achieved. The master level controls should be set in
such a manner that they are close to the center of their travel
(0 dB) to take advantage of the maximum control action. It
is poor practice to set up the input channels at too high a level
which will require the user to run the main levels at a low set¬
ting to achieve the desired result. Operation in this manner
will cause the operator to lose his "range" of the control ac¬
tion with all the gain located in one element while the other
is in the infinity position. This manner of operation also tends
to create headroom problems. Best practice calls for most con¬
trols to be operated near the middle of their operating range
to allow mixing control margins. Remember that while mix¬
ing it is important to allow yourself adequate margins within
which to operate. By using any of the controls in their extreme
positions, you have effectively reduced your operational
latitude.
These master controls allow the operator complete flexibility
of functions and should allow almost any mixing situation to
be handled. As with any reasonably complex system, ex¬
perience and operator knowledge of the equipment are essen¬
tial for satisfactory performance. The mixer, like the musician's
instrument, should be practiced on and learned. To properly
operate a mixer during a performance requires thorough
knowledge and trained reflexes to allow proper responses
under the stress of demanding and sometimes sudden
situations.
Please note that the master level controls have a 0 dB indica¬
tion. Operating within these ranges will assure the best com¬
bination of signal to noise ratio and headroom.
SUB MASTERS (A & B) (10)
The subs (A & B) are the main output level controls and regulate
the signal levels being supplied to the output jacks on the rear
panel Again, under normal usage, these controls should
be operated near the 0 dB range to allow optimum
performance.
The unique circuitry of the 701R Mixer derives a signal which
is the sum of the A and B outputs in order to make possible
operation of the A and B outputs as submasters to the sum.
As with the sub A and B controls, the sum should be operated
close to its middle (0 dB) range.
MASTER MONITOR CONTROL (11)
The master monitor control is located just above the sum
master control. Operation of this control is similar to that of
any rotary gain control on the mixer and should be set in con¬
junction with the respective individual channel monitor send
controls to achieve operation somewhere within the middle
rotation of the master control. The action of this control is con¬
ventional and should present no problem. The output signal
from the master monitor is available from the output connec¬
tors on the rear panel. Again, under normal usage, these con¬
trols should also be operated near the center of their range
to allow optimum performance.
EFFECTS RETURN CONTROL (12)
The effects return control may be considered an auxiliary in¬
put channel with a high impedance input and has been
designed to accept a wide range of audio signals. This ef¬
fects control is coupled to the effects pan, which then feeds
into the Sub A and Sub B mixing busses.
EFFECTS PAN CONTROL (13)
The effects pan control determines the relative balance from
the effects level control blended into the sub mixing busses.
EFFECTS TO MONITOR CONTROL (14)
The effects to monitor control enables signals from the effects
return input to be mixed back into the monitor mixing bus.
This unique feature enables external effects such as echo
units, flangers, delay lines, etc., to be blended back into the
monitor output signal if desired.
REVERB RETURN CONTROL (15)
The reverb return control determines the amount of delay
(reverb) signal blended back into the subs.
REVERB PAN (16)
The reverb pan control determines the relative balance from
the reverb level control blended into the sub mixing busses.
REVERB TO MONITOR CONTROL (17)
This unique circuit of the 701R Mixer allows mixing of
reverberation signal back into the monitor mixing bus for those
who do not prefer a "dry" monitor sound. (NOTE: Feedback
may be more pronounced with reverb on the monitors.)
EFFECTS MASTER CONTROL (18)
The effects master control is the final control element deter¬
mining the output level from the effects send jack on the rear
panel, as well as the amount of reverb drive delivered to the
internal reverberation system. Please note that no reverbera¬
tion effect may be achieved unless the individual channel ef¬
fects send controls and the effects level control are adjusted
properly.
STEREO OUT (19)
Controls the level appearing at the stereo output jack at the
rear panel. (See back panel)
LED OUTPUT LEVEL INDICATION (20)
NOTE: The two, 10-segment LED ladders on the front
panel are extremely important visual "tools" and their
operation must be understood to achieve maximum
benefits from this mixing system. The two LED displays
have a unique "switching" system allowing each ladder a
"dual" function. The switch located to the left of the LED lad¬
ders enables the operator to choose either the Sum (switch
in the "in" position) or sub A (switch in the "out" position)
output levels to be displayed on the left LED ladder. The switch
to the right of the LED ladder allows a choice of Monitor
(switch in the "in" position) or sub B (switch in the "out" posi¬
tion) output levels on the right LED ladder.
The LED ladders feature an extremely effective "warning
system" for all of the above mentioned functions. Should the
LED ladders reach the 6 dBV LED (top of the ladder reading),
the remaining LEDs automatically "shut-down" giving the
operator an instant visual indication that the possibility of clip¬
ping might be present. NOTE: Under normal operating con¬
ditions, the channel levels and master controls for Sub
A, Sub B, Sum, and Monitor should all be operated near
their center positions (0 dB indicated). This type of opera¬
tion will ensure that the possibility of clipping (overload) is
at a minimum.
Each channel of the 701R Mixer has a 10 dB LED level in¬
dicator. This red LED serves as a warning device for the
operator indicating that any particular channel has reached
10 dBV (3V RMS), and the possibility of "clipping" could
occur. Actual "clipping" occurs at 18 dBV, so when the LED
flashes, 8 dB of headroom is left. If this LED stays lit con¬
tinuously, the operator should reduce the input gain control
on that channel. Occasional flashing on "peaks" can be con¬
sidered normal.
POWER SWITCH/PILOT LED (21)
The power switch is of the simple 2-position "rocker" type
with the pilot LED immediately below it. Operation of this
switch is conventional and should present no problems in
operation. The "on" position will be indicated when the LED
pilot light glows, signifying power is being delivered to the mix¬
er circuitry.