Operating Instruction Manual
TOA PROFESSIONAL GRAPHIC EQUALIZER
Model E 111, E 112
E 111
E 112
TOA ELECTRIC CO,LTD.
KOBE, JAPAN
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General Description
The TOA E 111 is a single channel, 1/1 octave active graphic equalizer designed
to allow clean, accurate audio equalization for stage, studio, or commercial
applications, while the E 112 is a double channel version.
The E 111 and E 112 provide 12dB of boost or cut at each of its 10 frequencies per
channel, which are centered at ISO 1/1 octave increments from 31.5Hz to 16kHz.
The center frequency of each filter is continuously variable over a range of one
octave and the "Q" of each filter is continuously variable from 1.5 to 8. Its signal
to noise ratio is over 120dB making the E 111 and E 112 one of the quietest
equalizers on the market.
The active bandpass/bandreject filters of the E 111 and E 112 are designed for
minimum phase shift, and feature smooth slide controls with center detents for
easy and accurate adjustment. The filters are summed in parallel for reliability,
so that the failure of one filter does not interrupt operation of the others.
In addition, high-pass and low-pass filters are provided on the front panel. The
high-pass filter has a slope of 12 dB per octave and its cutoff frequency is 40Hz,
while the low-pass filter has a 12 dB per octave slope and its cutoff frequency is
12kHz.
An input level control on the E 111 or E 112 gives 12 dB of adjustment to allow a
wide variety of input sources. An LED indicator illuminates when either the
input or the output comes within 6 dB of clipping. In addition to the usual EQ
in/out switch, an automatic EQ bypass function provides complete equalization
bypass in the event of loss of AC power, and an output muting function
suppresses turn-on/turn-off transients.
A smoked plastic security cover is included with the E 111 or E 112 to guard
against accidental disturbance, or intentional tampering when used in fixed
installations.
Inputs and outputs are transformer-isolated and balanced, with both XLR and
1/4" stereo phone jacks. Ground lift switches are provided at both inputs and
outputs to reduce hum and prevent ground loops.
The E 111 and E 112 can be mounted in a standard 19" rack and occupy 5-1/4" of
vertical space. The rugged front panel is made of 1/8" (3mm) cast aluminum,
backed with a 1/8" (3mm) steel liner for added durability.
Features
1. 10 filters per channel on ISO 1/1 octave
center frequencies from 31.5Hz to 16kHz.
9. High- and low-pass filters.
10. LED peak indicator to detect clipping at input
or output levels.
2. 12dB boost or cut at each center frequency,
continuously variable.
11 Variable input level control to accept variety
of input sources.
3. Continuously variable center frequency
control at each frequency over a one octave
range.
12. Automatic EQ bypass circuitry.
4. Continuously variable "Q" control at each
frequency from 1.5 to 8.
13. Transformer-isolated balanced inputs and
outputs with XLR connectors and phone
jacks.
5. Signal to noise ratio greater than 120dB.
6. High quality, low phase-shift active filters.
14. Ground lift switches on input and output.
15. Smoked, plastic security cover is included.
7. Precision calibrated, noiseless slide controls
with center detent.
16. Heavy aluminum die-cast front panel, stand-
ard 19" rack mountable.
8. Equalizer In/Out switch.
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Specifications
Frequency Response
ldB, 20Hz to 20kHz
Total Harmonic Distortion
Less than 0.2% at 1kHz, all sliders at 0
position, rated output
Equalization Center Frequencies
From 31.5Hz to 16kHz
peaking type
31.5Hz (22Hz to 44Hz)
63Hz (44Hz to 88Hz)
125Hz (88Hz to 176Hz)
250Hz (176Hz to 350Hz)
500Hz (350Hz to 700Hz)
1kHz (700Hz to 1.4kHz)
2kHz (1.4kHz to 2.8kHz)
4kHz (2.8kHz to 5.5kHz)
8kHz (5.5kHz to 11kHz)
16kHz (11kHz to 22kHz)
Range of Adjustment of "Q"
1.5 to 8
Input Impedance
10k ohms
Output Impedance
600 ohms
High Pass Filter
40Hz, 12dB/octave
Low Pass Filter
12kHz, 12dB/octave
Hum and Noise
-103dB* (EQ IN, all sliders at 0 position, A
curve by IHF)
Protect
AC fail safe
Power Consumption
E 111: 10W
E
112: 19W
Dimensions
483(W)×l33(H)×370(L) mm
19(W)×5.25(H)×l4.6(L) inches
Weight
E 111: 7.6kg (17 lbs)
E 112: 8.8kg (19 lbs)
Finish
Equalization Control
12dB
Input Level Control
12dB
Black
Indicators
Rated Input Level
+4dB
Peak Indicator LED turns on at 6dB before
clipping
Rated Output Level
+4dB
EQ, Power Indicators Green Color LED
Accessories
Maximum Input Level
+24dB* at 1kHz
AC Cord, Cord Clamp
Maximum Output Level
+24dB* with 600-ohm load
*0dB is referenced to 0.775 volts RMS.
Appearance
The E 111 is the same in dimension as the E 112.
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Performance Graphs
FREQUENCY RESPONSE
(Each slider is set at a max position)
FREQUENCY RESPONSE (ex. 1kHz slider)
FREQUENCY
FREQUENCY
CENTER FREQUENCY CONTROL
(ex. 1kHz slider)
BANDWIDTH CONTROL (ex. 1kHz slider)
FREQUENCY
FREQUENCY
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Front Panel
E 111
E 112
Equalizer LED indicator
Allows adjustment of frequency response by using the EQ sliders
frequency controls while the LED remains lit. The frequency response is flat regardless of the position
, bandwidth controls
and Centre
of the EQ sliders when the LED is extinguished. Select either of the frequency modes with the equalizer
switch
Peak LED indicator
Lights when the output exceeds 6dB before a clipping level is reached. For minimum noise, a d j u s t the
input controls
so the LED can come on occasionally. When the LED still lights up even if the input level
control
is fully turned to "-12", decrease the o u t p u t level of equipment connected to the rear-mounted
input XLR connector or jack
Highpass filter switch
Attenuates the frequency component lower than 40Hz at the rate of 12dB per octave in the IN position.
Lowpass filter switch
Attenuates the frequency component higher than 12kHz at the rate of 12dB per octave when IN.
Equalizer switch
Placing the switch in the IN position causes the equalizer LED indicator
to turn on, and provides the
frequency response adjusted with the EQ sliders
controls
, bandwidth controls and centre frequency
. With the switch in the OUT position, the equalizer LED goes out and the frequency response
is flat just as the EQ sliders
allow for a flat response when set to "0".
Input level control
Adjusts the input level within range of -12dB to +12dB. Adjusting the control so the peak LED indicator
may occasionally light up reduces noise generated in the E 111 and E 112 equalizers. When the peak
indicator
still comes on even if the control is fully turned to the "-12" position, decrease the output
level of equipment connected to the rear-mounted input XLR connector or jack
EQ sliders
Provide 12dB of boost or cut at each of the 10 frequencies, which are centred at ISO 1 octave increments
from 31.5 to 16 kHz.
Bandwidth controls
Adjust a bandwidth. ("Q" is adjustable within range of 1.5 to 8.)
Centre frequency controls
Adjust the centre frequency within range of 1 octave.
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Front Panel
Power LED indicator
It is possible to operate the E 111 and E 112 equalizers while the LED remains lit. While the LED is OFF, the
signal fed to the rear-mounted input connector or jack
as it is.
is delivered to the output connector or jack
Power switch
Pushing this switch causes the power LED
again pushing the switch, the power LED
mounted input connector or jack
to light and puts the equalizer in the operation mode. By
can be extinguished, permitting the input fed to the rear-
to be delivered to the output connector or jack
as it is.
Tampering protection cover
Prevents accidental move of switch or control that has been set. Always fit the cover in place except when
it needs to be removed for adjustment.
Rear Panel
E
1 1 1
E 112
Fuse
Be sure to use the fuse of same type and capacity as are instructed.
Power inlet
An accessory power cord connects here. A use of the U-shaped clamp supplied with the equalizer by
inserting it into the holes provided above and below the power inlet is recommended to prevent accidental
disconnection of the power cord.
Ground lift switch
The switch is used to avoid earth loop that causes hum noise when the equalizer (E 1ll/E 112) is
connected to other equipment. By shifting the switch to the LIFT position, the earth loop may be cut.
Normally, set the switch to NORM.
Output connector and phone jack
A balanced type connector and jack with output impedance of 600 ohms. Both are wired in parallel.
Input connector and phone jack
A balanced type connector and phone jack with input impedance of 10k ohms. Both are wired in parallel.
Power cord hangers
Wind the power cord onto the hangers when the equalizer (E 1ll/E 112) is not in use.
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Input/Output Connections
Mixing Console (RX-7)
Power Amplifier
150D
P
E 112
Speaker System
38-SD×2
Installation Precautions
Ground Loops
In any audio system, there are numerous ways by which ground loops can be created. For
example, they may occur when the E 111/112 are mounted in a rack cabinet, or through AC
ground when the E 111/112 are connected with preamps, mixers, etc. These ground loops
may cause hum and noise if care is not taken during connection. An increase in noise from
ground loops may be minimized by breaking the ground loop. Generally, the chassis
ground of the signal line should be broken as shown below.
Rack cabinet
Main AC Ground
When a Y cord is used, shorten the wiring to minimize noise.
Ground lift switches are provided on the rear of the E 111/112. Sliding the ground lift
switch from a NORM position to the LIFT position lifts ground.
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Installation Precaution
On the road use
The E 111/112 are sturdily constructed with an aluminum die-cast front panel that is
reinforced by means of an iron plate attached to its back. To ensure that strength is
maintained during their transportation from one place to another, however, you should
also reinforce each unit from the back of the rack with a special support bracket. This can
be accomplished by removing cord-hangers on the rear panel, and screws that hold the
rear panel to chassis, and fitting the special support brackets through the holes.
Top view
Special support bracket
Side view
Functions
Center Frequency Control
The Center Frequency (fc) of each frequency band is
continuously variable within a range of one octave
(between 0.7fc and 1.4fc). Thus the overall frequency
response may be delicately adjusted. For example, if
the 1kHz center frequency control has a 12dB boost,
the frequency response looks like that of curve 1. If the
center frequency control is turned anticlockwise, the
response will be like curve 2, while in the case of it
being turned f u l l y clockwise, the frequency response
will be as shown by curve 3.
Bandwidth Control
The "Q"of each filter is continuously variable from 1.5
to 8. If the bandwidth control is turned clockwise, the
bandwidth is adjusted to approximately a one octave
range, while in the case of it being turned fully
anticlockwise, the bandwidth is adjusted to aproxi-
mately a 1/6 octave range as shown in the right figure.
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Applications
Feedback Prevention
When the overall gain of a sound system is increased, feedback will occur at frequencies
where the system response has peaks. Suppose the system has an uneven frequency
response like that shown in the following diagram. The frequency at which feedback will
occur when gain is increased is about 500Hz. In this case, feedback may be prevented by
attenuating levels at 500Hz by 5dB to 7dB with the E 111/112. If the overall gain is again
gradually increased, feedback will occur next at about 125Hz. It may be stopped by
attenuating the levels 2dB to 3dB at that frequency. In this procedure, sufficient gain in
the sound system is obtained before feedback. When the equalizer is used for this
purpose, the bandwidth controls are turned anticlockwise to prevent affecting other
frequencies not needed for equalizing. In addition, the frequencies at which feedback will
occur are not necessarily the same for each system and environment, therefore the
equalizer is more effective if the center frequency control is made use of to precisely
match center frequencies with the frequencies at which feedback occurs.
Room Equalization
In a sound reinforcement system for a room, the clarity of sound can be adversely affected
by the room frequency response including standing waves (room resonances), reflections
of sound, and relations between direct and indirect sound.
The E 111/112 are effective tools to equalize the room frequency response to a flat
response and improve sound clarity.
The effective use of the equalizer sliders, center frequency controls, and bandwidth
controls make it easy to equalize various frequency responses in rooms to be flat.
For example, suppose that there is a room frequency response as shown below.
Frequency
The equalizer sliders, center frequency controls and bandwidth controls are set as shown
below.
The response of those frequencies at which the corresponding equalizer sliders are set to
0dB positions will remain unchanged regardless of the positions of the center frequency
controls and bandwidth controls. The overall response after equalization will then be as
follows.
Frequency response
of equalizer
Frequency response
after equalization
Before equalization
Frequency
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Applications
Equalization for music
The Graphic Equalizer is designed not only for use in preventing feedback and equalizing
uneven room frequency response to be flat, but also for equalizing frequency response to
your tastes and producing favourable sound for you. Fig. 1 shows each frequency band
and its corresponding auditory feeling. Fig. 2 and Table 1 show the relation between each
musical instrument and its frequency band. They can be of great help in the equalizer
operation. (They are referenced from a book entitled "Practical Guide for concert")
EQUALIZATION CHART
These sounds
are felt more
The rythm section
appears here. Either
a fat or thin sound
can be heard by
mis-EQ here. Too
Probably the most
important of all.
Most all instru-
Upper vocal re-
gion. Too much
here will cause
great fatigue, and
loose speech in-
Presence
range.
Sibilance levels
Great achievement
in overall level can
be had here. Too
little causes a "far
away" sound.
can be
trolled
Bright,
con-
here.
clean
than
really
heard.
They
ments
contain
give a sense of
power.
harmonics here.
300Hz boosting can
definition.
Too
much
becomes
telligence.
Re-
much produces
a muddy sound.
boomy. Bass guitar-
Snare-Toms.
cause
horn-like
ducing 3k can
bring vocals on
top.
sounds. 1k to 2k
sounds tinny. Too
much here sounds
like the telephone.
Figure 1
INSTRUMENT CHART
INSTRUMENT EQUALIZATION CHART
Acoustic guitar
Bass strings resonate between 70 to 120Hz, body
around 300Hz. Avoid boosting these to stop feedback.
3kHz and 5kHz gives great "clarity".
Electric guitar
Bass guitar
Resonances differ — depending on type. Good full
sounds around 300 to 500Hz. Clarity at 3kHz.
Extreme lows are at 60 to 90Hz. "Pick" or "pluck"
sounds are around 800 to 1200Hz. Upper harmonics
clarified about 3kHz.
Human voice
Good fullness at 150Hz. Watch for "boominess" around
250Hz. Mid-range 10kHz.
Piano (Acoustic)
Piano (Electric)
Bass strings resonate around 100Hz. Watch for sub-
harmonics at 30 to 50Hz.
Good mid-clarity at 3kHz to 5kHz thins out rapidly in
high end. Be careful around 1.5kHz to 2.5kHz to avoid
the "bar room sound".
Organ
Violin
Usually dies under 200Hz. Has great mid-sounds
around 1200 to 2000Hz. Top end cuts off at 6kHz.
Richfullness at 400Hz. Natural mids around 1500 to
2500Hz. Avoid "scratch" sounds at 8kHz.
Brass instruments Watch for "hot" mids around 2kHz. Low end boost
around 400Hz. Top end clarity at 6kHz.
Bass drum
Snare drum
Tom Tom
Great low "kick" at 40Hz. The mids at 2kHz gives the
familiar "punch".
Good fullness at 100Hz. The "crack" is boosted at 2kHz.
real easy. The snares extend to above 4kHz.
The main fullness is around 200Hz. The mid punch
extends to 4kHz.
Floor Tom
Hi Hat
Same as tom, but extends down to 80Hz.
Watch for the "gong" sound around 300Hz. Good
"shimmer" sounds are around 8kHz to 10kHz.
Cymbal overhead About the same as hi-hat only has more low end around
150Hz.
Talk Box
Depending on the guitar sound driving it and the reso-
nance of each player's mouth, should have great "bite"
around 1200Hz and dies above 6kHz.
Table 1
Figure 2
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TOA ELECTRIC CO, LTD.
KOBE, JAPAN
Printed in Japan
133-02-688-3
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