Nady Audio GEQ 131 User manual

GEQ Series
EQUALIZERS
Graphic Equalizers
OWNER’S MANUAL

GEQ Series
Graphic Equalizers
Date of Purchase ____________________________________
Dealer’s Name ______________________________________
City _______________________________________________
State _____________________ Zip _____________________
Model # ____________________________________________
Serial # ___________________
3
Compact and durable all-steel chassis design, the GEQ Series provides optimum audio control for all live and recording applications,
plus ultimate operating convenience and maximum reliability.
FEATURES
TABLE OF CONTENTS
Congratulations on your choice of graphic equalizers — you have
purchased one of the finest graphic equalizers on the market
today. This unit was developed using the expertise of professional
sound engineers and working musicians. You will find that your
new NADY AUDIO Equalizers has superior performance and
greater flexibility than any other equalizers in its price range.
Please read this manual carefully to get the most out of your new
unit.
Thanks for selecting NADY AUDIO as your choice in graphic
equalizers.
• GEQ 131: 1 Channel, Single Rack Space,31 -1/3rd Octave
Bands
• GEQ 215: 2 Channel, Single Rack Space,15 -2/3rd Octave
Bands Each Channel
• GEQ 231: 2 Channel, Double Rack Space, 31 -1/3rd Octave
Bands Each Channel
• Active balanced (XLR and 1/4"TRS) input/output connectors
• Constant Q bandwidth from each filter with 3% center frequency
accuracy
• Parallel filter design for minimal phase distortion
• Ultra low-noise circuitry
• Low-cut filter at 40Hz, 12dB/octave, switchable, with status LED
• Band range: +/- 12dB gain
• Center detents on faders
• Variable input level control (+/-12dB)
• Equalizer ON/OFF bypass switch with status LED
• Gain status LED bargraph with peak LED
• Power switch with integral LED “ON” indicator
• Shielded internal power supply with AC input and selectable line
voltage (~115V/60Hz or ~230V/50Hz)
• Compact and durable all-steel chassis design
FEATURES ................................................................................. 3
WARNING ................................................................................... 4
INSTALLATION .......................................................................... 5
FRONT PANEL CONTROLS & CONNECTIONS ...................... 6
REAR PANEL CONTROLS & CONNECTIONS ........................ 7
TYPICAL SET-UP ....................................................................... 8
Sound Reinforcement Applications ...................................... 8
Musical Instrument Applications .......................................... 8
Studio Applications .............................................................. 8
SPECIFICATIONS ...................................................................... 9
NOTES ...................................................................................... 10
GEQ 131 —1 channel, single rack space (1U), 31-1/3 Octave bands with 1/3 octave ISO spacing from
20Hz to 20KHz
GEQ 231 —2 channel, double rack space (2U), 31-1/3 octave bands each channel with 1/3 octave ISO
spacing from 20Hz to 20KHz
GEQ 215 —2 channel, single rack space (1U), 15-2/3 octave bands each channel with 2/3 octave ISO
spacing from 25Hz to 16KHz.

4
IMPORTANT SAFETY INSTRUCTIONS
WARNING
ATTENTION: RISQUE DE CHOC ELECTRIQUE NE PAS OUVRIR
An equilateral triangle enclosing a lightening flash/arrowhead symbol is
intended to alert the user to the presence of uninsulated “dangerous
voltage”within the product’s enclosure which may be of sufficient
magnitude to constitute a risk of electric shock.
An equilateral triangle enclosing an exclamation point is intended to alert
the user to the presence of important operating and service instructions in
the literature enclosed with this unit.
When using this electronic device, basic precautions should always be taken, including the following:
1. Read all instructions before using the product.
2. Do not use this product near water (e.g., near a bathtub, washbowl, kitchen sink, in a wet basement, or near a swimming
pool, etc.).
3. This product should be used only with a cart or stand that will keep it level and stable and prevent wobbling.
4. This product, in combination with headphones or speakers, may be capable of producing sound levels that could cause
permanent hearing loss. Do not operate for a long period of time at a high volume level or at a level that is uncomfortable.
If you experience any hearing loss or ringing in the ears, you should consult an audiologist.
5. The product should be positioned so that proper ventilation is maintained.
6. The product should be located away from heat sources such as radiators, heat vents, or other devices
(including amplifiers) that produce heat.
7. The product should be connected to a power supply only of the type described in the operating instructions or as marked on the
product. Replace the fuse only with one of the specified type, size, and correct rating.
8. The power supply cord should: (1) be undamaged, (2) never share an outlet or extension cord with other devices so that the
outlet’s or extension cord’s power rating is exceeded, and (3) never be left plugged into the outlet when not being used for
a long period of time.
9. Care should be taken so that objects do not fall into, and liquids are not spilled through, the enclosure’s openings.
10. The product should be serviced by qualified service personnel if:
A. The power supply cord or the plug has been damaged.
B. Objects have fallen into, or liquid has been spilled onto the product.
C. The product has been exposed to rain.
D. The product does not appear to operate normally or exhibits a marked change in performance.
E. The product has been dropped, or the enclosure damaged.
11. Do not attempt to service the product beyond what is described in the user maintenance instructions. All other servicing should
be referred to qualified service personnel.

INSTALLATION
5
To ensure years of enjoyment from your NADY AUDIO graphic
equalizer, please read and understand this manual thoroughly
before using the unit.
These three equalizer models are each designed for mounting in
a standard 19" equipment rack or one of the many rack type
portable cases available on the market. The units are either 1u
single rack (1.75") or 2u double rack (3.5") as noted. All three
models are 5 inches deep.
Install the equalizer in a rack with rack screws (not included).
Route the A.C. power cord to a convenient power outlet away
from audio lines. The unit may be turned on and off from the front
panel power switch or a master equipment power switch. Since
the unit draws a relatively small amount of current during idle, the
unit may be left on continuously. NADY AUDIO equalizers do not
generate an unduly large amount of heat and do not need to be
specially ventilated or cooled. The units should not be subjected,
however, to high heat environments.
Although the unit is shielded against radio frequency (RF) and
electromagnetic interference (EMI), extremely high fields of RF
and EMI should be avoided.
INPUT/OUTPUT CONNECTIONS
The 1/4" phone jack and XLR connector inputs and outputs can
be used for balanced and unbalanced connections. CAUTION:
Using more than one connector at a time for the INPUT/OUTPUT
pair could unbalance balanced lines, cause phase cancellation,
short a conductor to ground, or cause damage to the other
equipment connected to the equalizer.
Paralleling inputs and outputs may be accomplished by using any
of the 3 connectors.
Note: The 1/4" TRS are normally used for this function.
For balanced connection,
wire the connectors as follows:
For unbalanced operation,
wire the connectors as follows:
POWER CONNECTION
Each of these three NADY AUDIO graphic equalizers is designed
for operation with 105-130 volts AC at 60Hz or 210-240 volts AC
at 50Hz power sources . Power requirements for electrical
equipment differ from area to area. In new installations and
portable sound systems, or any situation in which the AC power is
in question, it is wise to confirm the voltage and select the
appropriate line voltage switch before connecting the instrument
to power sources.
Check to see that the unit is set to the voltage for your area by
referring to the table below:
Europe (except UK): 230V, 50Hz
UK and Australia: 240V, 50Hz
USA and Canada: 115V, 60 Hz
For other areas, please check with local authorities.
If the voltage selector is not set for your area:
Confirm that the power cord is not plugged into a wall outlet. Move
the voltage selector switch with a small screwdriver so that the
marker is set to the voltage for your area.
PRECAUTIONS
Protecting yourself from electric shock:
•Never touch the plug with wet hands.
•Always pull out by the plug and never the cord.
•Only let a qualified professional repair the equipment. An
unauthorized person might touch the internal parts and receive a
serious electric shock. Note: Removing the chassis screws and
opening the unit will automatically void your warranty.
•Never allow a child to put anything into the equipment.
Protecting your NADY AUDIO Graphic Equalizer:
•Use only a household AC power source. Never use a DC power
source.
•If water is spilled on or in the unit, unplug it and call for service.
•Make sure that the equipment is well ventilated and away from
direct sunlight
•Avoid damage to the internal circuits and the external surface by
keeping the unit away from sources of high heat.
•Avoid using spray type insecticide or solvents near the equip-
ment. It can damage the finish an might ignite suddenly
•To avoid damaging the finish, never use denatured alcohol, paint
thinner or other similar chemicals to clean the equipment.
•Place the unit on a flat and solid surface or in a rack.
•To enjoy your NADY AUDIO graphic equalizer for a long time,
please read this owner’s manual thoroughly.

FRONT PANEL CONTROLS & CONNECTIONS
6
1. Power Switch
To turn the equalizer ON or OFF, press the upper or lower portion
of this button. The internal LED indicator will light when the unit is
on.
CAUTION: Always turn on your equalizer BEFORE your power
amplifiers are turned on, and always turn off your equalizer
AFTER your power amplifiers have been turned off to avoid any
turn on/off transient noise.
2. Gain Control
The Gain control allows adjustment between OFF (center detent)
and +/-12dB. This control is used to adjust for variation in input
level to the equalizer channel, or to compensate for the equaliza-
tion applied to the input signal. Unity gain can be achieved by
setting this control to its center detent position. The unit is
equipped with a red Peak LED, which illuminates when the signal
reaches 3dB prior to clipping. It is acceptable for the Peak LED to
flash occasionally, however, if the Peak LED is flashing steadily,
the Gain control should be reduced to avoid distortion.
3. Low-Cut Filter
This switch enables a low cut filter at 40Hz, 12dB/octave to
remove unwanted low frequencies from the signal to prevent
stage rumble and low frequency resonance that can occur while
using speakers in an enclosed acoustic environment. The LED
status indicator will light yellow when the Low Cut is enabled.
4. EQ ON/OFF
This switch enables or bypasses the equalizer filters. If you
disable the EQ ON/OFF switch, the LED will turn off and the unit
will be in bypass mode. In bypass mode, the audio signal will flow
through without any equalization although the Gain control will still
be active.
5. Output Level LED Bargraph
This four-stage LED bargraph illuminates according to the output
signal level. The red Peak LED lights at 3dB prior to clipping.
Occasional blinking of the Peak LED is acceptable, but if it
remains on more than intermittently you should turn down either
the equalizer’s level controls or reduce the input Gain level.
6. Filter Level Slider Controls
Each one of these linear potentiometers will boost or cut its noted
frequency by +/-12dB. When all of the sliders are in center detent
position, the output of the equalizer is flat. Each slider is marked
with the center frequency of its band pass filter.
2 16
2 3 5
1 6
1
6
GEQ 131
GEQ 215
GEQ 231
3 4 5
4
2 3 4 5

REAR PANEL CONTROLS & CONNECTIONS
7
7. IEC Power Cord Receptacle
This is used to connect the AC power source to your equalizer. Power requirements: 115/230VAC, 50/60Hz
8. AC Voltage Selector
Set this slide switch to match your line voltage supply.
CAUTION: For new installations and portable sound systems, or in any situation in which the AC power is suspect, it is wise to confirm
appropriate voltage and line polarity BEFORE connecting the instrument to the power source.
9. Fuse Holder
This fuse holder contains an AC primary fuse. This fuse should be replaced with the same type fuse when this is blown out. If they
continuously blow, stop replacing the fuse and refer servicing to qualified personnel.
CAUTION: After checking the AC supply voltage, be sure that the correct fuse is in the fuse holder. A 20mm glass tube 200mA 250V
fast-blow fuse should be used.
10. Input/Output Connectors
XLR and 1/4" TRS balanced Input/Output jacks for desired active balanced or unbalanced line level operation. Line level signals from -
18dBu to +18dBu are considered normal. Do not directly connect microphones into the equalizers. Microphones require a pre amp.
Note: Only one input and one output connector should be used at a time.
7
9
810
GEQ 131
GEQ 215
GEQ 231
7
9
8
10
9 8
7
10

8
TYPICAL SET-UP
NADY AUDIO graphic equalizers may be used wherever modification of the frequency contour of a sound system is needed. A graphic
equalizer is a solution to any number of sound problems or creative urges.
SOUND REINFORCEMENT APPLICATIONS
By routing the signal from the mixer to the main power amplifiers (or crossover), the overall frequency of the mix may be altered to do
a number of things.
A. Through the use of a real-time audio spectrum analyzer, a calibrated microphone, and a pink noise source, the audio system may
be “TUNED”to make the overall audio spectrum response of the audio reinforcement system and the room environment flatter in its
frequency response.
B. By turning up the audio reinforcement system to the feedback point, then attenuating the oscillating frequency (1/3 octave resolu-
tion), then turning the system up to attenuate the 2nd oscillating frequency, and then the 3rd, and so on, you can enable the entire
audio system to have much more gain before feedback.
C. Amplifiers and speakers may be protected by the use of the LOW CUT feature of the equalizer. Wind noise or the loud percussive
sound of dropped microphones, etc., could potentially cause damage to the amps and/or speakers. By rolling off the extreme LOW
frequencies with the LOW CUT filter, a measure of protection is added to the system without severely affecting the overall sound
quality.
D. In noisy environments, the audio signal may be tailored for better intelligibility and penetration. This is especially useful for public
address systems.
E. Creative use of the equalizer allows shaping of the signal for a more pleasing sound or for special effects. The only limits are those
of taste and imagination.
MUSICAL INSTRUMENT APPLICATIONS
A. Putting an equalizer in line with a musical instrument allows you to modify the sound of the instrument. You can brighten the sound,
or add body to a thin sounding instrument, or even give the sound a totally different character.
B. An equalizer will allow you to eliminate unwanted sounds, like a 60-cycle HUM from a badly grounded amplifier.
STUDIO APPLICATIONS
A graphic equalizer is one of the most useful tools in the sound engineer’s bag. NADY AUDIO equalizers offer the features and
flexibility to perform where it counts in the studio.
A. Fix a track that doesn’t sound quite right. Put the equalizer in an effects send and return it to the MIX bus.
B. Create an artificial stereo by splitting a monaural signal and equalizing the split signals differently, then panning one equalized
signal to the right and the other signal to the left.
C. Shape the sound by changing the frequency response of the track.
D. Special effects, like a telephone sound, can be created by cutting off the LOW end to 200Hz and the HIGH end to 6KHz.

SPECIFICATIONS
9
EQUALIZER:
Equalizer Control Bands
1X31, 1/3 Octave ISO Spacing From 20Hz to 20KHz
2X31, 1/3 Octave ISO Spacing From 20Hz to 20KHz
2X15, 2/3 Octave ISO Spacing From 25Hz to 16KHz
Filter Type
Constant Q
Slider Travel
20mm (Center Detent) for GEQ 131/215/231
Level Control Range
+/-12dB
INPUTS:
Type
Active Balanced/Unbalanced
Connectors
3-Pin XLR, 1/4" TRS (Balanced), RCA (Unbalanced)
Impedance
40K Ohms Balanced; 20K Ohms Unbalanced
Maximum Level
28dBV
OUTPUTS:
Type
Active Balanced/Unbalanced
Connectors
3-Pin XLR, 1/4" TRS (Balanced).
Impedance
Typically < 400 Ohms
Maximum Level
+/-20dBV
Clip LED Threshold
3dB (Below Clipping)
Low Cut Filter
40Hz, 12dB/octave
Frequency Response
20Hz - 20KHz, +/- 1dB
THD + Noise
<0.008% (@ 1KHz, all faders at mid position)
Signal to Noise Ratio
95dB (@ 1KHz)
Channel Separation
60dB (1KHz)
Line Voltage
100-130V AC, 50/60Hz
200-240V AC, 50Hz
Power Consumption
Maximum: 15 watts
SIZE:
19"W X 3.5"H X 5"D (2U)
(48.2cm X 8.8cm X 12.7cm) For 231
19"W X 1.75"H X 8.66"D (1U)
(48.2cm X 4.4cm X 12.7cm) For GEQ 131/215
WEIGHT:
4.15lbs. (1.9Kg.) GEQ 215
4lbs. (1.81Kg.) GEQ 131
6.85 lbs. (3.1Kg.) GEQ 231
The specifications above are correct at the time of printing of
this manual. For improvement purposes, all specifications for
this unit, including design and appearance, are subject to
change without prior notice.

NOTES
10

SERVICE FOR YOUR NADY AUDIO PRODUCT
(U.S.) Should your NADY AUDIO product require service, please contact the Nady Service Department via telephone
at [phone], or e-mail at [e-mail].
(International) For service, please contact the NADY AUDIO distributor in your country through the dealer from
whom you purchased this product.
DO NOT ATTEMPT TO SERVICE THIS UNIT
YOURSELF AS IT CAN BE DANGEROUS AND
WILL ALSO VOID THE WARRANTY.
NADY SYSTEMS, INC. •6701 SHELLMOUND STREET, EMERYVILLE, CA 94608
Tel: [phone] •Fax: [phone] •www.nady.com