Specifications

6
Operating Manual - LX-308B Stereo Line/Microphone Mixer
BACK PANEL FEATURES
1 Inputs
The LX-308B stereo inputs use two balanced 1/4"
TRS phone jacks per channel, with (+) signal on the tip, the
(-) signal on the ring, and ground on the sleeve. If you wish
to drive a mono source into the stereo mix, simply plug your
signal into the right channel input. Channels 1 and 2 have
switchable 30dB added gain for low impedance dynamic mi-
crophones (Right inputs only). Input impedance on mic inputs
(ch.1 R & ch.2 R only) is 1.86kΩ, all other inputs are 20KΩ.
2 Sub In
The Sub inputs are nominal 10KΩ unbalanced types
on 1/4" phone jacks. They feed directly to the mix busses at
a nominal +4dBu level and are useful for coupling multiple
mixers.
3 Sub Out
The Sub Outputs are unbalanced types on 1/4" phone
jacks. Typically, they will feed sub inputs on additional mixers.
Nominal operating level is +4 dBu.
4 Main Outputs
Right, left, and mono outputs are 200Ω servo-
balanced on 1/4" phone jacks. Nominal operating level is +4
dBu and maximum headroom is +22dBu.
5 Wiring Suggestions
If low level and high level lines (e.g., microphones
and mixer line outputs), or if either of these lines and speaker
cables are run parallel for long distances, crosstalk may be sig-
nificant. In fact, the crosstalk (signal leakage between cables)
can cause an electronic feedback loop, oscillation, and possibly
damage to the equipment. To minimize crosstalk, physically
separate low level (microphone) cables from speaker cables by
the greatest feasible distance. At any point where cables meet,
run low level cables perpendicular to high level or speaker
cables. If low and high level or speaker cables must be run
parallel and in close proximity to one another, they should be
bundled separately.
TROUBLESHOOTING TIPS
No Sound
Check the AC power. Is the power switch on and the
power LED illuminated? Check the level meters. If they are
operating, the problem between the mixer and the later com-
ponents in the system. If not, check to see you really have an
input signal and that it is on the desired channel. Check that
you have the master gain controls at the desired operating level.
Distorted Sound
Something is being overdriven in the signal path. If
the clip indicators are active, reduce the channel level controls.
If the clip indicators are still active, reduce the input signal
level. If the level meters are constantly in the red, reduce the
Master gain and increase the gain of components following
the mixer. There are many gain adjustments in the mixer itself
and probably several others in other system components which
makes it possible to overdrive an input section and then incor-
rectly try to reduce the gain of the output section. The best way
to approach setting gains is to establish the operating level of
input stages first by setting their gain as high as possible but
leaving about 20dB of headroom for loud peaks, then move
on to set the master gain to produce a good meter reading.
Proceed to set the gain of equalizers, limiters, crossovers, and
amplifiers following the mixer in the same manner, always
working toward the later stages of the system.
Excessive Noise
If the noise is in the form of hiss, the problem is usu-
ally due to an input stage set up for low gain and then com-
pensating by increasing the master gain. Turn up the channel
level controls and reduce the master gain.
Excessive hum
This is usually caused by "ground loops" in the system
wiring. A complex sound system with many sources separated
by significant distance and using several power outlets has
many opportunities for this problem to occur. If possible,
feed everything in the system from one power source with a
common ground.
If you need help, get in touch with your Ashly dealer
or call an Ashly technical service representative at 1-800-
828-6308.