4. Slowly attenuate the Equalizer control which has
the greatest effect on reducing the ringing. This will
take some trial and error - the first ringing usually
occurs between 1 kHz and 4 kHz. Continue until the
ringing has stopped.
5. Again, slowly increase the output level control until
the system is on the verge of feeding back. Adjust the
equalizer to remove the potential feedback. Continue
this procedure until you have achieved sufficient gain
for your application or until the equalizer becomes
ineffective at removing the ringing. It is best to back
off the gain once maximum gain before feedback has
been established. Avoid extreme settings or settings
which require a large amount of cut in the middle fre-
quency bands, as such settings impair intelligibility.
6. “Fine tune” the equalizer settings as the perfor-
mance progresses to achieve the best overall sound
from the system.
4-3. CORDS AND CABLES.
4-3-1. MICROPHONE CORDS. On the SR mixers, use
balanced two-conductor shielded cable for all long
runs. Balanced systems are capable of rejecting noise
introduced from such sources as cash registers, electric
motors and triac-controlled lights. If a balanced cable
is connected to an unbalanced output (e.g., a key-
board mixer output) or microphone, use a balancing
transformer close to the unbalanced device. This
ensures maximum common-mode noise rejection for
the entire system.
If you have no choice and must use unbalanced
cables, use the shortest cables possible and keep them
away from AC power mains, lighting cables and
speaker wires. If you want the quietest system possi-
ble, you should follow these rules with balanced lines
as well.
4-3-2. SPEAKER CABLES. Use two conductor zip cord
to connect the amplifier outputs to your speakers. The
gauge of the wire is important; wire that is too light in
gauge consumes power (the power from the amplifier
heats up the wire for your particular situation). To cal-
culate your speaker impedance, use Figure 3.
4-4. INPUT PADS. If input signal levels are too great,
the input stage may be overdriven and cause distor-
tion. The solution in such cases is to use an input pad.
A 30 dB pad can be made by using a Switchcraft con-
nector (part #S3FM) with the resistor network shown
in Figure 4.
4-5. PATCHING. Figures 5 through 8 show possible
ways of patching external equipment into the SR
mixer. They are by no means the only patches possi-
ble. If you want to try a patch that is not illustrated,
consult the Block Diagram to determine if your patch is
possible. When patching external equipment into the
signal chain, best results will be obtained by following
these rules:
• Use the highest quality patch cords available
and keep them as short as possible.
• Avoid patching a buss output back into its input.
An example of this is patching a phase shifter
from the EFF. OUTPUT / REVERB FOOTSWITCH
and returning it to the input of a channel which
has its EFF./REV. control turned up. Doing so
may result in oscillation (possibly inaudible)
that can damage loudspeakers and create dis-
tortion.
• Do not use a mic level or instrument level effect
(such as an effect intended for guitar) with a line
level signal (such as the Main or Graphic EQ
output).
5. UPKEEP AND SERVICE
The SR powered mixers have been designed to give
years of trouble free service. With a few precautions,
you can help to insure its continued reliable service.
• Do not obstruct the air vents on the rear panel.
• Transport the mixer with care.
• Periodically inspect the mixer for damage which
may occur during transportation.
• If you leave the mixer set up when you are not
using it, protect it from dust with a soft cover.
DO NOT SET FOOD OR BEVERAGE on the SR powered
mixer - this can not be overemphasized. Spilling a
drink can be the quickest way to ruin a potentiometer
(fader, level control, EQ control) or switch.
• When using the mixer protect it from
moisture (rain, sprinklers, beer, etc.)
• Periodically clean the mixer by wiping it
with a soft cloth and a small amount of fur-
niture polish.
6. TROUBLESHOOTER'S CHECKLIST:
If the mixer is set up but does not function, check the
following items:
-Is the mixer power cord properly plugged into an
electrical outlet?
-Is there power at the outlet?
-Are the speakers properly hooked up to the
mixer?
-Are the proper controls turned up?
-Is the instrument turned up?
-Check all cables and wires.
If, after checking all of the above, the mixer is still not
performing correctly, consult your Fender Service
Dealer.
