Nady Systems SPA 1400 User Manual

AMPLIFIERS

SPA Series

Stereo Power Amplifiers

OWNER’S MANUAL

SPA SERIES

STEREO POWER AMPLIFIER

Offering top power, superior performance and full professional
operating features in a roadworthy compact chassis, the SPA
Series are perfect for even the most demanding sound
reinforcement installation and touring applications.

The operating instruction in this manual are for the SPA850,
SPA 1400 and SPA 2400 power amplifiers. The operation and
functions of these units are the same, except as noted.

• Continuously variable speed fan with back-to-front air flow

• Full operating features: user-defeatable clip limiter; switchable
30Hz low-cut filter; balanced XLR and 1/4” TRS inputs; detent
volume controls; stereo (dual-channel, parallel-input, or bridged
mono operating models with selector switch; binding post and
Neutrik Speakon™ outputs; ground-lift switch

• Complete, advanced safety/reliability features: soft-start turn on;
noise-free on-off; built-in DC offset; independent DC and
thermal overload protection on each channel; short circuit and
speaker protection; DC servo operation; built-in current limiter

• Parallel outputs allow “daisy chaining” amps

• ~115V (60Hz)/~230V (50Hz) AC select switch

• Clip and Signal LED indicators for each channel

• Durable double rack space (2U) steel casing

• SPA 850 — 2 x 350W @4Ω, 2 x 425W @2Ω
Bridge mono: 600W @ 8Ω, 850W @ 4Ω
SPA 1400 — 2 x 500W @4Ω, 2 x 800W @2Ω
Bridge mono: 1000W @ 8Ω, 1400W @ 4Ω
SPA 2400 — 2 x 750W @4Ω, 2 x 1400W @2Ω
Bridge mono: 1600W @ 8Ω, 2400W @ 4Ω

Congratulations on your choice of stereo power amplifiers —
you have purchased one of the finest stereo amplifiers 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 SPA 850/1400/2400 has
superior performance and greater flexibility than any other
amplifiers 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
amplifiers.

Date of Purchase __________________________________________
Dealer’s Name ____________________________________________
City______________________________________________________
State____________________Zip ______________________________
Model # __________________________________________________
Serial # __________________________________________________

FEATURES ..................................................................3

WARNING....................................................................4

FRONT AND REAR CONTROLS................................5

INSTALLATION............................................................7

CONNECTIONS ..........................................................8

BLOCK DIAGRAM ......................................................10

SPECIFICATIONS ......................................................11

FEATURES

CONTENTS

3

WARNING

IMPORTANT SAFETY INSTRUCTIONS

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.

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.

4

1. POWER SWITCH

To turn the unit ON or OFF, press the upper or lower
portion of this button. Before turning on the amplifier, check
all connections and turn down the level controls. A
momentary muting is normal when turning the amplifier on
or off.

(Caution: Always turn on your power amplifier last, after all
your other connected equipment, and always turn off your
power amplifier before your other connected equipment.)

2. POWER LED INDICATOR

This LED illuminates when the power is turned “ON”.

3. CLIP (PEAK) LED INDICATORS

These LEDs illuminate if any section of the power

amplifier’s output are within 3DB of clipping. Occasional
blinking of the LEDs are acceptable, but if they remain on
more than intermittently you should turn down either the
power amplifier’s level controls or reduce the output level
of the preceding component to avoid audible distortion.

4. SIGNAL LED INDICATORS

These LEDs illuminate to confirm the presence of an input
signal greater than 100 mV at that channel of the amplifier

5. LEVEL CONTROLS

These control the level of signal coming into each channel.
The actual voltage gain of the amplifier is shown in dB.
Turn these controls counterclockwise if the peak LEDs
illuminate steadily (indicating too strong an input signal).

FRONT AND REAR CONTROLS

1

1 2 3

5

FRONT P

ANEL

5

4

6. CIRCUIT BREAKER

A bimetallic circuit breaker is provided for protection of the
amplifier. Press to reset if it trips. If it continuously trips
upon resetting, refer servicing to qualified personnel.

7. POWER CONNECTOR

The cord connector is used to connect the AC power
source to your power amplifier.

(CAUTION: DO NOT REMOVE THE CENTER
GROUNDING PIN.)

8. GROUND LIFT SWITCH:

Switch to right to disconnect the chassis from ground if
necessary to eliminate hum caused by ground loops.

9. AC VOLTAGE SELECTOR SWITCH:

Before plugging in the power cord, check to see that the
unit is set for the proper voltage for your area: ~115V
(60Hz) or ~230V (50Hz). Acover plate is provided to
ensure that this switch is not accidently reset or tampered
with between uses.

10. L/R CHANNEL OUTPUT CONNECTORS

(Speakon™ & Binding Posts)

The Speakon™ and binding post (banana jack) outputs are
compatible with a speaker load of 2 Ω or greater (4Ω or
greater for bridged operation). Connections are as
depicted on the rear panel and in the following
CONNECTIONS section on page 8 of this manual.

REAR PANEL

6

7

9

8

6

FRONT AND REAR CONTROLS

11. BALANCED INPUT CONNECTORS

(1/4” TRS & XLR)

These 1/4” (6.3mm) TRS (Tip/Ring/Sleeve) phone jacks
and XLR jacks are compatible with balanced inputs and
are wired as Tip/Pin 3 = (+), Ring/Pin 2 = (-), and
Sleeve/Pin 1 = Ground. Normal maximum input level at
clipping is 1.15V RMS (+ 4dB). Input impedance is 10K
Ohms. Since the TRS phone jacks and XLR jacks are
wired internally in parallel, you can parallel this unit with
another amplifier by using either the LINE 1/4” jack or the
XLR jack (depending on which you’re using to input your
signal) to output the signal to the input jack of the other
amplifier.

The 1/4” TRS phone jacks can also be used for
unbalanced inputs. For TRS phone plugs, simply connect
the unused side of the balanced input to ground. For 1/4”
TS phone plugs, no change is necessary for compatibility
with this input. Balanced input signals are recommended
as they are less prone to AC hum. For long cable runs a
source of less than 600 ohms output impedance is needed
to avoid signal loss. For short cable runs an unbalanced
signal input should be suitable.

For stereo (two-channel) operation, use the inputs for both
CH-A and CH-B; for parallel or bridged mono operation,
use only CH-A input. (See 13-MODE SELECTOR
SWITCHES below for more explanation.)

12. CLIP LIMITER SWITCH

This switches the internal Clip Limiter ON or OFF for both
channels. The limiter prevents excessive signals from
overloading the amplifier (and thus flattening the peaks of
the waveform and introducing distortion) by automatically
lowering the amplifier gain to minimize overdrive. This
limiting is primarily used to protect full-range speakers
from high frequency distortion or damage to the horns
caused by bass overdrive. However, when driving a
subwoofer, defeating the limiter can produce a desired
extra “punch” to bass instruments, such as kick drums.

13. MODE SELECTOR SWITCH

The SPA Series amplifiers offer 3 modes of operation:
PARALLEL, STEREO & BRIDGED. Slide the switch to
one of the three positions for you application.

• PARALLEL (MONO) INPUT— This mode allows
both channels to operate in parallel with the same
signal and without requiring a Y-cord. In this mode
the inputs for both channels are internally connected,
so that you only need to feed a signal into one of the
channels. This still allows independent control of
each channel. It also enables easy “daisy-chaining”
with other amps by using the other set of input
connectors.

(Note: Do not select this “Parallel” mode when
feeding the amplifier 2 separate signals.)

(Note: Do not use both unbalanced and balanced
cables in the same set-up as that can unbalance all
the connections when daisy-chaining, resulting in
hum.)

• STEREO INPUT — This is the most common
mode generally used, and allows independent
control of 2 separate signals such as stereo
playback, main and monitor live mixes, and bi-amp
operation (highs in one channel and lows in the
other).

• BRIDGED MONO — This mode combines the
power of both channels to drive a single speaker. In
this mode the amp produces 4 times the peak power
and 3 times the sustained power into a 4 or 8 ohm
speaker than each channel can deliver separately in
stereo or parallel mode.

(CAUTION: In this mode the amplifier can deliver
high power into a speaker. Make sure that the
speaker, connectors and wiring can handle this
output. Note that for prolonged overdriven outputs
into a 4 ohm speaker the breaker may trip, so care
must be taken not to overload the amplifier in such
operation.)

Connect the input signal to CH-A input for bridged
mono operation.

14. LF FILTER (30HZ) SWITCH

The low frequency LF filter rolls off frequencies below
30Hz when this switch is turned to the ON position. This
filter improves the audio by limiting unwanted inaudible low
frequency speaker cone movement. Unless a preceding
device, such as a mixer, already has such a 30Hz roll-off,
this filter should generally be employed for optimum audio
and to protect your speaker from excessive cone
excursions beyond its rated limit at sub-audio frequencies.
Generally this switch should only be left “OFF” if you are
monitoring the whole signal for frequency content, such as
for studio playback.

15. FAN

The fan speed is varied continuously automatically to
maintain the proper internal operating temperature. Rear­to-front airflow keeps amps and racks cool.

7

INSTALLATION

Rack Mounting

The SPA Series amplifiers are designed for standard 19”
rack mounting as well as “stack” mounting without a
cabinet. Use 4 screws and washers for mounting to the
front rack rails. It is also a good idea to support the amps
also in the rear, especially for mobile use where the amps
will be subjected to shocks.

Amplifier Cooling

Also pay close attention to the cooling requirements. Since
the airflow is from the rear to the front, it is important to
keep both the inlet in the rear and the output in the front
clear of obstructions to enable efficient cooling airflow.
Since the amp exhausts to the front it does not contribute
to heat buildup in the rear of the rack. It is important,
however, that the other devices used in the rack allow
plenty of cool air in the rear to enable proper cooling of the
amp. Never block the air vents in the sides and front of the
amplifier if the load seen by amplifier is less than 4 ohms
and the amplifier is being run at high output levels. For
best results, in such high output power applications you
should augment the amplifier’s air flow with a rack cooling
system.

Internal Fuse Protection

Each of the SPA Series amplifiers has backup internal
fuse protection on each channel on the secondary output
circuitry of the power transformer. In almost all cases of
power overload the external back panel circuit breaker,
which is wired in the primary power input circuit of the
power transformer, will trip before the internal fuses blow.
Nevertheless, these fuses are valuable in that they can
sometimes isolate the problem to a single channel,
allowing operation of the other channel. Also, because
they require added effort to rectify, they increase the
vigilance of the operator in correctly eliminating the cause
of the overload problem before further use. These fuses
are located inside the units and require removal of the top
of the chassis.

CAUTION: Never open the unit when connected to AC
power as you can be severely shocked resulting in serious
injury or even death. Please wait at least 5 minutes after
disconnecting the unit from AC power to let any internal
capacitors discharge before opening. )

Replace the fuse with the same type, size and power
rating as noted in the illustration for your SPA Series amp.
If it continuously blows, stop replacing the fuse and refer
servicing to qualified personnel.

Internal Fuses for SPA 850/1400

Internal Fuses for SPA 2400

SPA 850 10A/250V (x2)

SPA 1400 12A/250V (x2)

both 3AG Fast Blow

SPA 2400 25A/250V (x2)

both 3AG Fast Blow

The following instructions describe the most common ways to install your amplifier into a sound system.

1. Turn off the amplifier power switch before making any connections.

2. The SPA Series amplifiers maybe operated in one of three modes (stereo, bridged-mono, and parallel mono).
Refer to the following wiring diagrams for the speaker connections you wish to make.

(Note: Nady Systems assumes no liability for damaged speakers resulting from improper wiring, careless amplifier
use, or over powering.)

• Stereo (Two-Channel) Mode

To put the amplifier into stereo mode, first turn the amplifier off, then slide the mode selector switch (13) to the center
“STEREO” position, and properly connect the input/output wiring as shown.

(Note: Do not connect a speaker load less than 2 ohms as it can damage your amplifier.)

8

CONNECTIONS

CHANNEL B

CHANNEL A

CHANNEL B

PIN 1+

+

-

PIN 1-

CHANNEL A

PIN 1+

+

-

PIN 1-

(Note: You can also connect
both channel outputs to the
Channel A Speakon™. Ch A
Pin2+ = ChB Pin1+ and Ch A
Pin2- = Ch B Pin1-)

1

2

3

2

1

3

Ground (Screen)

Cold (-)

(Out of Phase Signal)

Hot (+)

(In Phase Signal)

MICROPHONE INPUTS

Socket (female) Plug (male)

UNBALANCED USE OF

MONO 1/4” PLUGS

Tip =
Signal

Sleeve =
Ground/Shield

Tip

Sleeve

Strain relief
clamp

BALANCED USE OF

STEREO 1/4” PLUGS

Tip =
hot (+)

Ring =
cold (-)

Sleeve =
Ground/Shield

Tip

Ring

Sleeve

Strain relief
clamp

Input Wiring Tips

• Parallel (Mono) Mode

To put the amplifier in parallel-mono mode, first turn the amplifier off, then slide the mode selector switch (13) to the
left “PARALLEL (MONO)” position and properly connect the input/output wiring as shown. A signal into any input jack
will drive both channels directly. You can patch the input signal on to any other amps suing any of the remaining input
jacks.

(Note: Do not connect a speaker load less than 2 ohms as it can damage your amplifier.)
[Note: Do not use the “PARALLEL (MONO)” switch when feeding the amp 2 separate signals.]

• Bridged Mono Mode

To put the amplifier in bridged mono mode, turn the amplifier off and slide the mode selector switch (13) toward the
right “BRIDGED” position and properly connect the input/output wiring as shown. The signal is input into CH-A. Keep
the level control of channel “B” turned completely down (counter clock wise).

(Note: Do not connect a speaker load of less than 4 ohms as it can damage your amplifier.)
(Note: This mode produces a large amount of power. Be sure that your wiring and speaker can handle it.)

9

CHANNEL A

CHANNEL A

PIN 1+

+

-

PIN 2+

Do Not Use

Do Not Use This Speakon™

for Bridge Mode

CONNECTIONS

CHANNEL A

CHANNEL B

PIN 1+

+

-

PIN 1-

CHANNEL A

PIN 1+

+

-

PIN 1-

To additional amplifier(s)

for “daisy-chaining

(Note: You can also connect
both channel outputs to the
Channel A Speakon™. Ch A
Pin2+ = ChB Pin1+ and Ch A
Pin2- = Ch B Pin1-)

10

BLOCK DIAGRAM

11

SPECIFICATIONS

POWER SPECIFICATIONS SPA 850 SPA 1400 SPA 2400

2Ω 425 800 1400
EIA out power 4Ω 350 + 350 500 + 500 750 + 750
1Hz, THD maximum 1% 8Ω 200 + 200 300 + 300 500 + 500
Both channels Bridged 8Ω 600 1000 1600W

4Ω 850 1400 2400

ELECTRICAL SPECIFICATIONS SPA 850 SPA 1400 SPA 2400

INPUT SENSITIVITY 1.15V (+3.4dBU) 1.15V (+3.4dBU) 1.15V (+4dBU)
INPUT IMPEDANCE 10KΩ Unbalanced & Balanced

FREQUENCY RESPONSE 25Hz~25KHz +0/-1dB
(at 10dB below rated output power -3dB points: 5Hz~50KHz

VOLTAGE GAIN 30dB 32dB 34dB
DISTORTION (SMPTE-1M) <0.03% <0.03% <0.03%
S/N ratio 100dB 100dB 100dB

GENERAL SPECIFICATIONS SPA 850 SPA 1400 SPA 2400

Full short circuit, open circuit, thermal, ultrasonic, and RF
protection; stable into reactive or mismatched loads;
ON/OFF muting; current limiter (crowbar)
Front: Power switch, 40 detent input level control for each
channel. Rear: Parallel/Mono/Bridge selector, 30Hz filter
selector, clip ON/OFF selector, ground lift switch,
AC voltage selector switch, AC breaker
SIGNAL: 2 x green LED
CLIP: 2 x red LED
POWER: 1 green LED
POWER: IEC power cord jack
INPUT: Active balanced XLR and 1/4” (6.3mm) TRS
OUTPUT: “Touch-proof” binding posts
SPEAKON™ Connectors

POWER SUPPLY Voltage selectable: 110-120V or 220~240V AC 50/60Hz

11A 15A 20A
10A/250V, 3AG, 12A/250V, 3AG, 25A/250V, 3AG,

Fast Blow (x 2) Fast Blow (x 2) Fast Blow (x 2)
DIMENSIONS 19.0” x 15.7” x 3.5” (483 x 400 x 88.8mm)
WEIGHT 29.9lb (13.6Kg) 34.3lb (15.6Kg) 41.8lb (19Kg)

CONTROLS

INDICATORS

CONNECTORS

PROTECTIONS

FUSES

AC Primary — Rear Panel Breakers
AC Secondary — Internal Fuses

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.

NADY SYSTEMS, INC. • 6701 SHELLMOUND STREET, EMERYVILLE, CA 94608

Tel: [phone] • Fax: [phone] • www.nadywireless.com

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.