III. SYSTEM CONNECTION
Exactly WHERE you install your ME 15 or ME 30 into a sound system can significantly effect
such things as hum, noise, system headroom, compressor/limiter performance and other
factors that influence overall sound quality. Both WHAT and WHY you are equalizing will also
determine where you install it. We’ll leave the WHEN and WHO entirely up to you.
1. WHAT AND WHY. Most outboard equalizers are used to correct and/or enhance the
acoustical performance of a sound system: everything is under control until the program
material reaches the speakers--then trouble begins. EVERY speaker system reacts drastically
different in each room in which it’s located, resulting in feedback problems, absorption nodes,
resonances and everything else short of chicken pox. This is where the equalizer comes in-to
alter the ELECTRICAL performance of the program material in order to COMPENSATE for the
ACOUSTICAL PROBLEMS in the system. This seems very basic, but many fall victim to misuse
of the system equalizer: boosting several low frequency filters when a simple boost of the bass
guitar controls is what’s really needed. Don’t use the system equalizer to make specific tonal
changes in vocals or instruments; use the MIXER EQ controls for this.
2. WHERE. Since most equalizers are used for acoustical correction, the equalizer should be
one of the LAST pieces of gear in front of the amplifiers and active crossovers. Any further up
the line may cause electrical mismatch with other line level equipment.
Here are a few GENERAL guidelines which may be useful in deciding exactly where to install
the ME 15/30 in the system.
1. DOWNSTREAM OF ANY COMPRESSOR/LIMITER. Since system EQ is aimed at the
ACOUSTICAL problems, it should be installed AFTER any compressor/limiters, which are
designed to operate on electrical program material. For one thing, the equalizer slider settings
will change with each new location, which in turn would affect the control voltage and
threshold responses of any compressor/limiter it is driving and render it inconsistent.
Secondly, healthyamounts of boost will often strain the dynamic range of compressor/limiters
and increase the danger of distortion and/or overload.
2. AFTER ANY SYSTEM GAIN Here is a trap many will fall into: mixer, compressor/limiter,
equalizer, active crossover and power amplifier--all with gain controls, and all working
AGAINST each other. The ME 15/30 has incredibly low noise levels, but it IS a line level, active
component. If you have the ME 15/30 level control way down (to avoid overdriving the
compressor/limiter which is wrongly connected AFTER it), then you must turn UP the limiter,
crossover and amplifier controls to compensate; now you’ll blame the equalizer for being too
noisy. Whenever headroom will allow, try to take all the gain you can right at the mixer, and run
unity levels from there on. This should give better noise performance from the mixer, as
well. Connect the ME 15/30 just before the amplifier or active crossover if one is used. Take any
required line gain before and/or in the ME 15/30; avoid taking a lot of gain in the crossover or
power amps as this may create noise or hum problems.
3. BE CAREFUL WITH SEND/RECEIVE LOOPS. Mixers, mixer/preamps and the like often
provide send/receive loops for additional effects or EQ, and the ME 15/30 will work well in this
situation. Just be sure to keep input trim or gain controls turned up as far as the mixer input
headroom will allow, to avoid taking excessive gain downstream and creating noise problems.
Remember to feed the ME 15/30 with roughly line level program (between -10 dBV and
+4 dBm to +20 dBm), and all should work fine.
