Rane GE 60 User Manual

Page 6

Manual-

ACOUSTIC COMPENSATION

A graphic equalizer may be used to correct many acoustic

problems. However, one should fully understand the ramifica-

tions of doing so. Acoustic problems are generally not consistent

across the entire area of sound coverage. This is much more of a

problem when setting up a sound system for large venues. In a

typical large room or hall, there will be areas that have acoustic

reinforcement problems and other areas where certain frequen-

cies are almost entirely canceled out. Try to seek an acoustic

remedy for acoustic problems whenever possible. When this is

not possible or feasible, an equalizer may be used to compensate

for an acoustic problem. But the problem is only improved at

the point where the measurement is taken, other locations in the

room may be adversely affected by the equalizer setting. For this

reason, measure the acoustic response of the system from several

locations and average the equalizer’s setting. Doing this helps

most locations in the venue to have an equal sound quality.

The best way to “see” what the acoustic signature of the room

is doing to sound is to use a real time analyzer or any of the

many computerized measurement systems. Using these devices

to analyze the response of the room and the sound system is the

only accurate means available for setting an equalizer properly.

Equalization can be like spice in the hands of a master chef.

A little goes a long way in improving sound quality, too much

and the mix is spoiled. If modest amounts of equalization (6-8

dB) do not solve the problem, it is best remedied by other means.

Avoid adding large amounts of boost below 63 Hz, especially

when using vented bass cabinets. Boosting frequencies below

the vented enclosure’s low frequency cutoff can easily cause over

excursion of the speaker’s cone, causing premature failure. In ad-

dition, boosting low frequencies can make your power amplifier

run hotter, leading to premature amplifier failure.

When equalizer adjustment is completed, compare the un-

equalized sound with the equalized sound by alternately engag-

ing the BYPASS switch. Use familiar source material and walk

around in the sound coverage area to insure that no anomalies

have been introduced into the sound system. If it sounds good,

you’re done.

TONE CONTOURING

If a GE 60 is used for tone contouring by ear, be care-

ful about adding upper bass (63 Hz to 200 Hz) as this causes

“muddiness” or loss of clear definition. (Also see the previous

warning about boosting frequencies below 63 Hz). Middle

frequency problems usually express themselves by vocals having

a nasal quality (too much mid band boost) or vocals not being

easily understandable (usually caused by mid band frequencies

being under represented in the overall sound). High frequency

problems show as “sizzle”— not good, and is sometimes caused

by too much high frequency boosting. This is most obvious

with cymbals and hi-hats. To use the cooking metaphor, high

frequencies should simmer, not sizzle.

OPERATING INSTRUCTIONS

Insuring the proper level of gain though the GE 60 is just

as important as adjusting the equalizer bands. Improper gain

distribution is a common cause of loss of system headroom and

less than optimum noise performance.

The OVERLOAD LED informs of an imminent or passed

overload to the equalizer. Occasional blinking of the OL with

program source material is fine, indicating optimized signal-to-

noise performance. Run the GE 60 with an input signal that is as

hot as possible without the OL lighting more than occasionally.

The BYPASS switch allows comparison of equalized versus

un-equalized signal. It is also useful in adjusting the level of the

GE 60 for unity gain and best signal-to-noise performance. The

gain of the GE 60 is optimized when there is no sound level dif-

ference between the bypassed and the active positions.

The overall gain range of the level control for the GE 60 is off

to +2 dB for unbalanced operation, or off to +8 dB for balanced

operation. The level difference between the equalizer in bypass or

active can be significant. Adjust the LEVEL control so the signal

level is the same between the bypassed and active positions of the

BYPASS switch.

GETTING STARTED

Here is one method of setting your equalizer that works well.

Begin with the following settings:

1. Engage the BYPASS switch. (switch depressed, BYPASS LED

on.)

2. Put all sliders in their center position (0 dB). The center posi-

tion has a grounded detent.

3. Position the LEVEL controls about “6” for unbalanced opera-

tion and “7” for balanced operation.

4. Set LOW and HI CUT filters fully down, corresponding to

10 Hz and 40 kHz.

5. Apply a signal to the system.

6. Verify the OL LED is not on—occasionally blinking during

extreme peaks indicates an optimal setting. But if it lights up

a lot or lights steadily, lower the output level of the previous

device in the signal chain.

7. Release the BYPASS switch and begin adjusting the equalizer

filters.

8. During filter band adjustments, if the OL LED lights more

than occasionally, turn down the output of the previous de-

vice in the signal chain.

9. Once all filter bands are adjusted to your liking, compare the

signal loudness with the equalizer bypassed and active. Adjust

the LEVEL controls on the GE 60 so there is no difference

between the levels of bypassed versus active.

10. The last step is to reconfirm that the OL LED lights only

when there are large signal spikes in the program material, as

in step 6 above.

For insight into how to use an equalizer, to alleviate acoustic

problems or to adjust the overall tone of the program material,

please read the following two sections.

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