Steg QM75.4 User manual

Car Audio Power Amplifiers
USER'S GUIDE
QM75.4
QM500.1

WARNING
WARNING This symbol means important instructions.
Failure to heed them can result in serious injury or death.
CAUTION This symbol means important instructions.
Failure to heed them can result in injury or property damages.
• STOP USE IMMEDIATELY IF A PROBLEM OCCURS. Failure to do so may result in personal injury or damage to the
product. Return it to your authorized STEG dealer.
• HAVE AN EXPERT DO THE WIRING AND INSTALLATION. This unit requires special technical skill and experience for
wiring and installation. To insure safety and proper function, always contact the authorized dealer where you purchased
the product to have it done professionally.
• INSTALL THE UNIT SECURELY WITH SPECIFIED PARTS. Be sure to use only the included parts and specified installation
accessories (not included). Use of other than designated parts may damage this unit. Install the unit securely so that it
will not come loose during a collision or sudden jolt.
• ROUTE WIRING AWAY FROM SHARP EDGES AND MOVING PARTS. Arrange cables and wiring away from sharp or
pointed edges and avoid moving parts such as seat hinges or rails to prevent pinching or wear. Use loom protection
where appropriate and always use a grommet for any wiring routed through metal.
• NEVER RUN SYSTEM WIRING OUTSIDE OR UNDERNEATH THE VEHICLE. All wiring must be routed, secured and
protected inside the vehicle. Failure to do so may result in fire, injury or property damage.
• INSTALL THE UNIT IN A DRY AND VENTILATED LOCATION. Avoid mounting locations where the unit will likely be
exposed to high moisture or heat without adequate ventilation. Moisture penetration or heat buildup may result in
product failure. Always make sure the amplifier chassis temperature is safe before touching it.
• REDUCE GAIN AND SOURCE VOLUME TO MINIMUM LEVELS FOR INITIAL SYSTEM TUNING. Ensure amplifier power is
off before connecting signal cables and follow proper system gain setting procedures. Failure to do so may result in
damage to the amplifier and/or connected components.
CAUTION
1
Package Contents:
Main Unit
Accessories Required for
Installation (not included):
ŸRCA Interconnects
ŸPower/Ground/Speaker Wire
ŸIn-line Fuse Holder w/Fuse
ŸBattery Ring Terminal
ŸChassis Ground Terminal
ŸWire Crimp Connectors
ŸGrommets and Loom
ŸCable Ties
ŸMounting Screws
Remote Level ControllerTerminal(s)
(QM500.1 only)
• DO NOT DRIVE WHILE DISTRACTED. Any function that requires your prolonged attention should not be performed
while driving. Always stop the vehicle in a safe location before performing any such function. Failure to do so may result
in an accident.
• KEEP THE VOLUME AT MODERATE LEVELS WHILE DRIVING. Excess volume levels can obscure sounds such as
emergency vehicle sirens or road warning signals and may result in an accident. Continuous exposure to high sound
pressure levels may cause permanent hearing loss. Use common sense and practice safe sound.
• FOR USE WITH 12V NEGATIVE GROUND VEHICLE APPLICATIONS ONLY. Using this product other than in its designed
application may result in fire, injury or product damage.
•MAKE THE CORRECT WIRING CONNECTIONS AND USE PROPER FUSE PROTECTION. Failure to connect wiring
correctly with appropriate gauge and fuse protection may result in fire, injury or product damage . When replacing
fuse(s) in the unit, never exceed the specified rating. Ensure proper protection of all system power wiring and install an
external fuse (not included) with specified rating for each amplifier connected with the +12V lead at the battery terminal.
• DISCONNECT THE NEGATIVE BATTERY TERMINAL BEFORE INSTALLATION. Failure to do so may result in fire, injury or
damage to the unit.
• D O NOT ALLOW CABLES TO BECOME ENTANGLED IN SURROUNDING OBJECTS. Arrange wiring and cables to prevent
obstructions when driving. Cables or wiring that obstruct or hang up on places such as steering wheel, brake pedals, etc.
can be extremely hazardous.
• DO NOT DAMAGE VEHICLE SYSTEMS OR WIRING WHEN DRILLING HOLES. When drilling holes in the chassis for
installation, take precautions so as not to contact, puncture or obstruct brake lines, fuel lines, fuel tanks, electrical wiring,
etc. Failure to take such precautions may result in fire or an accident.
• DO NOT UTILIZE OR CONNECT TO ANY PART OF VEHICLE SAFETY SYSTEMS. Bolts, nuts or wires used in the brake,
airbag, steering or any other safety-related systems or fuel tanks should NEVER be used for mounting, power or ground
connections. Using such parts may disable control of the vehicle or result in fire.

INTRODUCTION
Notes:
Band-pass capability is available in CH3/4 of the QM75.4 model when its crossover mode
*switch is set to LPF(BP), enabling both the HPF and LPF frequency adjustments.
ŸAll specifications are subject to change without notice.
2
Thanks and congratulations for choosing STEG for your audio amplification needs.
These amplifiers have been significantly improved throughout the years in order to
assure quality and reliability. The latest technology has been incorporated into every
product, providing you with incredible power and unparalleled sound quality. Our
highly developed and simplified circuitry contributes to low distortion and the
ultimate in efficiency. That's why we are sure that your new amplifier will provide you
with a sound value you can enjoy for years to come.
Note: All specifications are subject to change without notice.
QM75.4 QM500.1
4Ω, 14.4V 75W x 4 200W x 1
2Ω, 14.4V 105W x 4 350W x 1
4Ω BTL, 14.4V 210W x 2 -
1Ω, 14.4V - 500W x 1
Frequency Response +0/-3dB, 1W, 4Ω <10Hz to >50kHz 15-255Hz
1W, 4Ω >85dBA >80dBA
Rated Pwr, 4Ω >103dBA >103dBA
Damping Factor 50Hz, 4Ω >125 >175
Distortion (THD+N) ½ Rated Pwr, 4Ω <0.1% <0.3%
RCA
>10kΩ>10kΩ
High Level
100Ω100Ω
RCA 500mV-8V 200mV-6V
High Level 2V-12V 2V-12V
Fuse Rating End Panel, ATC 30A x 2 30A x 2
High-Pass (HPF) 15Hz-3.5KHz, 12dB/oct. -
Low-Pass (LPF) 35Hz-3.5KHz, 12dB/oct. 45-255Hz, 12dB/oct.
Band-Pass (BPF)*
15Hz-3.5KHz, 12dB/oct. -
Subsonic - 15-55Hz, 12dB/oct.
Level 0 to +12dB 0 to +12dB
Freq (Fc) 45Hz 45Hz
Remote Level Control Volume Range - 0 to -20dB
Phase Shift Degrees -
0-180°
Idle Current <1.0A <1.0A
Sleep Current <1.1mA <1.4mA
Operating Voltage DC Supply 10-16V 10-16V
13.1"x7.2"x2.2" 10.4"x7.2"x2.2"
334x184x56mm 264x184x56mm
Dimensions (LxWxH)
Input Sensitivity
Specifications
Bass Boost
S/N Ratio
Crossover
Power Output (RMS)
Current Draw
Input Impedance

3
QM75.4
WIRING & CONNECTIONS
It is important to read this manual thoroughly before starting your installation and always plan accordingly.
Before installing, disconnect the negative (ground) wire from the vehicle’s battery to avoid damage to the
vehicle or yourself. Following all guidelines will help provide years of enjoyment with your STEG amplifier.
Power Supply Terminal
Œ
Ground (GND): The ground terminal must be connected to a metal part of the vehicle with ground
Ÿ
plane back to the main battery ground attachment point (a.k.a. chassis ground). This wire should be as
short as possible, but no longer than 2ft (60cm), with minimum gauge of 8AWG. The ground wire
should be terminated with a ground specific or ring terminal and securely bolted to the vehicle with
star or lock washer and nut to prevent from coming loose. The chassis ground connection point
should be scuffed to the bare metal.
Remote Turn-on (REM): A switched +12V lead must be connected to the REM terminal to turn on the
Ÿ
amplifer, such as the source unit's remote output or vehicle switched ignition wire.
ŸPower (+12V): The constant +12V power connection must be made at the vehicle main battery,
securely connected with a ring terminal and protected with an in-line fuse within 18in (45cm) from the
positive battery terminal. The QM75.4 and QM500.1 require a 60A fuse (not included) and a minimum
power wire gauge of 8AWG. Do not install the fuse until all other system connections have been made.
Fuses: These ATC fuses are to protect the amplifier and must be inserted for operation. When replacing

fuses, check for system wiring faults and always use the specified value for each fuse (30A).
Power/Protect LEDs (POW/PRO): These LEDs indicate the amplifer status. Green indicates the amplifier
Ž
is on and in normal operation. Red indicates the amplifier is in protection mode, due to overheating,
under-voltage or output short circuit condition.
Speaker Output Terminal

ŸSpeaker Outputs: Each (+) and (-) terminal pair per channel is for connecting the amplifier's output to
speaker(s) or subwoofer(s). Make sure to observe correct polarity and total impedance per channel. For
the QM75.4 model, the minimum nominal impedance is 2Ω per channel, or 4Ω for bridged
connections. For the QM500.1, the minimum total nominal impedance is 1Ω.
RCA Inputs (LINE IN): The RCA input jacks are for left and right channel signals from the source. Use

quality interconnects to ensure stable connection and minimize the possibility for induced noise.
Speaker Level Inputs (HIGH LEVEL): These inputs are for wired connection to a speaker level source,
‘
not to exceed 12Vrms. Make sure to observe correct polarity. For signals containing DC-offset, the
amplifier will automatically turn on without requiring a switched +12V connection at the REM terminal.
Remote Level Controller (REMOTE): This jack is available on the QM500.1 model only and is for
’
connecting the included remote level controller to the amplifier
Bridged Connection and Switch: This single RCA jack is for connecting two QM500.1 mono amplifiers
“
together in a bridged configuration to provide double power for subwoofer(s) with a minimum total
nominal impedance of 2Ω. Set the switch to "MASTER" on the amplifier connected to the source, and set
the other amplifier's switch to "SLAVE" to receive the bridged signal.
Œ Ž  Ž Œ
<2ft
(60cm)
Remote
Turn-on
12V Chassis
Ground
<18in
(45cm)
8AWG
(min)
12V
Remote
Turn-on
12V Chassis
Ground
<18in
(45cm)
8AWG
(min)
12V
QM500.1
y y‘ ‘ y’ “‘
<2ft
(60cm)

4
4-Channel 3-Channel (Stereo + Bridged)
2-Channel (Bridged)
QM75.4 Speaker Connection Examples:
Bridged Configuration Example:
2Ω
(min)
2Ω
(min)
2Ω
(min)
2Ω
(min)
2Ω
(min) 2Ω (min)
4Ω
(min)
4Ω
(min) 4Ω (min)
QM500.1 Subwoofer Connection Examples:
1Ω
(min) 2Ω
(min) 2Ω (min)
2Ω
(min)

5
CONTROL SETTINGS
The following settings and adjustments for the QM75.4 and QM500.1 models are provided to allow
customized tuning for a wide variety of system applications. Read each feature description carefully to
understand its application and function in order to the make the proper adjustments to maximize your
system's sound performance while minimizing the possibility to over-drive the connected speaker(s) or
subwoofer(s). For sensitive bandwidth limited speakers such as tweeters, be sure to set high-pass crossover
points appropriately for protection from lower frequencies before powering on the amplifier and then start
the tuning process at low to moderate sound levels.
Gain Adjustment (LEVEL): This adjustment is for matching the input sensitivity of the amplifier with
Œ
the maximum unclipped signal provided by the source. Follow proper gain setting procedures to ensure
optimum source volume range with minimum chance for clipping or over-driving the
speaker(s)/subwoofer(s). Aside from music, a -10dBfs sine wave tone at a frequency between the chosen
crossover points may also be used during the tuning process to ensure proper headroom and gain
overlap for typical music recording levels. Readjustment may be necessary after any changes to
crossover or bass boost settings.
Input Channel (MODE INPUT): This switch is available in the QM75.4 model only and selects the input

mode for either a 2-channel or 4-channel source. When 2CH is selected, input signal connections to
CH1/2 will be copied to CH3/4 inputs.
Crossover Mode (HPF/LPF/FULL): This switch is available in the QM75.4 model and is for selecting the
Ž
crossover mode. For CH1/2, it is selctable as a high-pass filter (HPF) or bypassed for full-range operation
(FULL). For CH3/4, it is also selectable as a low-pass filter (LPF) and band-pass (BP), which enables both
LPF and HPF frequency adjustments.
High-pass Filter (HPF): This adjustment is available in the QM75.4 model and sets the HPF cut-off

frequency (Fc) from 15Hz to 3.5kHz with a slope of -12dB/oct. For smaller full-range or component
speakers, use the high-pass (HPF) setting to filter out unwanted lower frequencies. Note that when set to
a very low frequency, this high-pass will act as a subsonic filter.
Low-pass Filter (LPF): This adjustment is available in the QM75.4 for CH3/4 and QM500.1 model, which

sets the LPF cut-off frequency (Fc) from 35Hz to 3.5kHz with a slope of -12dB/oct. For woofers or
subwoofers capable of reproducing only low frequencies, use this setting to filter out unwanted higher
frequencies. For the QM75.4 model, note that when CH3/4 crossover mode is set to LPF it will also
enable the CH3/4 HPF frequency adjustment for band-pass (BP) filter applications, such as a
woofer/midrange in an active 2-way component set, or act as a subsonic filter for a subwoofer when
used in 3-channel configuration.
Subsonic Filter (SUBSONIC): This adjustment is available in the QM500.1 model, and sets the subsonic
‘
filter cut-off frequncy from 15-55Hz with a slope of -12dB/oct. Use this adjustment to optimize
subwoofer performance by limiting the frequency response to what they can effectively reproduce and
minimize the chance of being over-driven. Very low frequencies can also waste amplifier power but this
setting is especially important for preventing damage to subwoofers from over-excursion in ported
enclosures below the tuning frequency.
Bass EQ (BASS BOOST): This provides level adjustment of a single EQ band centered at 45Hz from 0dB
’
up to +12dB. It is available in the QM75.4 for CH3/4, and in the QM500.1 model. Use this setting to
achieve desired bass response without over-driving the speaker(s)/subwoofer(s) or causing excessive
amplifier output distortion.
Phase Adjustment (PHASE SHIFT): This adjustment is available in the QM500.1 model, and provides
“
the ability to shift the signal phase from 0° to 180°. Unlike a typical polarity switch, this adjustment
allows variable adjustment of the output phase that can be used to alleviate bass cancellations with
other speakers in the system for improved frequency response.
Ž Ž Œ“
Œ
   ’
Œ
’ ‘
QM75.4 QM500.1

Warranty & Service Care
GT Trading warrants this product to be free from manufacturing defects for a period of one (1) year from
original date of purchase. Under this warranty, Wāvtech will replace the defective product on behalf of GT
Trading with a new or remanufactured one at no charge.
For speakers and component sets, only return the defective part. Do not return the other speaker, tweeter
or crossover as they will be retuned back to you. This warranty covers manufacturing defects only.
Wāvtech will test each item received to verify there is a defect. If no defect is found, the item will be
returned to dealer. Items misused, altered, or neglected are not covered. Wāvtech will not be liable for any
loss, cost of repair or any other damage of any kind connected with the use, or repair of its products. All
warranty returns require pre-approval and Return Authorization.
For Service within the United States:
Wāvtech Customer Service: [phone]
Monday – Friday, 8:30am to 5:00pm MST
Important Notice for International Customers:
For products purchased outside the United States of America or its Territories, please contact your local
distributor concerning specific procedures for your country's warranty policy. International purchases are
not covered by Wāvtech, LLC.
6
Serial Number:
Installation Date:
Place of Purchase:

ITALY
Distributed in the Americas by Wāvtech, LLC
www.stegaudio-usa.com
GT Trading reserves the right to make modifications or improvements without notice thereof. The availability
of the products illustrated is subject to change. The described in this User's Guide represent just a part of the
STEG products available. All brands and trademarks mentioned have been used exclusively for description
purposes and all rights belong to the respective owners, total or partial.
STEG is the Property of GT Trading
©Copyright 2021 Wāvtech, LLC. All Rights Reserved.
1350 W. Melody Ave.
Suite 101
Gilbert, AZ 85233
[phone]