MTX Thunder TH90.4 Owner's Manual
Text of the manual
4 Channel Class-AB Power Amplifier
600W RMS
Designed by MTX in Phoenix, USA
www.mtx.eu.com
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Introduction
Thank you for purchasing an MTX Audio Hi-Performance amplifier. Proper installation matched with MTX speak-
ers and subwoofers provide superior sound and performance for endless hours of waking the neighbors, slam-
min' your friends or flat out stomping wanna-be players. Congrats and enjoy the ultimate audio experience with
MTX !
Specifications :
• 4-Channel Class-AB amplifier
• CEA2006 certified Power Output :
- 150 watts RMS x 4-channels at 2 ohm and THD+N ≤1%
- 90 watts RMS x 4-channels at 4 ohm and THD+N ≤1%
- 300 watts RMS x 2-channels at 4 ohm and THD+N ≤1%
• Crossover :
- High pass 12dB/oct variable from 40Hz to 8000Hz
- Low pass 12dB/oct variable from 40Hz to 8000Hz
- Band pass 12dB/oct variable from 40Hz to 8000Hz
• Signal-to-Noise Ratio (1 watt) : > 81dB
• THD+Noise (Distortion) (1 watt) : ≤ 0,25%
• Frequency Response (±1dB) : 20Hz-20000Hz
• Maximum Input Signal : 6V
• Maximum Sensitivity : 100mV
• Dimensions : 383mm x 213mm x 52,5mm
• High level inputs with Smart Engage Technology
Features :
• XTC - (Xtant Technology Cooling) - A regulated thermal intercooler, injecting cool air through internal heat
sinks. Fan speed is load dependent and continuously variable, sampling the temperature of the heat sink and
transformers for maximum reliability. Intercooler exhaust is strategically placed to chill transformers and main-
tain exceptional performance at any volume level. (Cool eh ? An Amp with an Intercooler ! )
• Pure N-Channel Design - Patent N°: US05631608 and N°: US05783970 - MTX amplifiers incorporate N-
Channel MOSFETs on both the positive and negative circuits of the output stage (PURE N-Channel Design). No
additional circuits are needed to compensate for inefficient designs like P-Channel MOSFETs. Both the positive
and negative circuits have equal usable power ratings. Genuine Genius...Yea we know...
• EAF Technology (Efficient Auto Former) - Patent N°: US05598325 - Our Transformers are "Auto Formers"
which allows us to use smaller magnetics (-30% to -50%) yielding increased efficiency. Turn ratios are improved
due to series connections between the primary and secondary taps meaning MORE Power !
• Smart Engage™ Technology - Patent N°: US06556683 - The amp switches on and off automatically when
connected with high level inputs. No need for a remote turn on wire from under the dashboard. No need to
remove the head unit. Thanks MTX !
• Bi-Level Inputs - High level inputs (Speaker cables) and line level inputs (RCA) utilize the same RCA type input
connections on the amp.
Owner’s Manual - TH904
Control Panel :
Gain Control - The gain control matches the input sensitivity of the amplifier to the source unit being used. The
operating range varies from 100mv to 6V.
Adjusting the gain
1. Turn the gain control on the amplifier all the way down (counter clockwise).
2. Turn up the volume control on the source unit to approximately 3⁄4 of maximum.
3. Adjust the gain control on the amplifier until audible distortion occurs.
4. Adjust the gain control down until audible distortion disappears.
5. The amplifier is now calibrated to the output of the source unit.
Low Pass X-Over Switch - Turns the active low pass (LP) x-over on and off. When engaged (in) the x-over is “ON”,
when disengaged (out) the x-over is “OFF”
Low Pass X-Over Frequency Control - Used to select the desired low-pass (LP) x-over frequency. The frequency is
adjustable from 40Hz to 8000Hz.
High Pass X-Over Switch - Used to turn on the active high-pass (HP) x-over on and off. When engaged (in) the
x-over is “ON”, when disengaged (out) the x-over is “OFF”.
High Pass X-Over Frequency Control - Used to select the desired high-pass (HP) x-over frequency. The frequency
is adjustable from 40Hz to 8000Hz..
Band Pass X-Over : To use, turn “ON” the HP and LP x-overs at the same time, creating a band-pass x-over for kick
woofers or midranges. You can tune the filter with frequency controls (3) and (5).
Important Notice: When both x-overs are turned “OFF”, the pre-amp section is in “Direct” mode providing the
best possible sound quality.
Power On LED - The LED illuminates red when the amp is switched on. For Short or Thermal protection, see
points 9 and 10
Control Panel (Top)
Connectors Panel (Side)
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Owner’s Manual - TH904
Connectors panel :
RCA Inputs - These RCA inputs are used with source units that have RCA or
Line level outputs. (Source units need a minimum level of 100mV output for
proper operation of the amplifier).
MTX recommends only high quality twisted pair cables (such as StreetWires)
to decrease the possibility of radiated noise entering the system.
High Level Inputs :
MTX amplifiers allow high level inputs through RCA type input connections.
Simply connect the head unit speaker leads to the provided adapters.
Speaker Terminals - Connect speakers to these terminals. Observe speaker
polarity throughout the system. Improper phase can result in loss of bass re-
sponse and/or poor overall sound quality.
Bridge Mode:
When bridging the amplifier, use the left positive terminal and the right negative terminal only.
Warning : do not bridge the amplifier with an impedance lower than 4 ohm.
Thermal Protection - This LED illuminates red when the amp reaches 100°C. The LED also turns red when the
power supply goes below 9V or over 16.2V.
Short Circuit Protection - This LED will flash yellow when the speaker outputs will short circuit. Without signal,
this LED can remain yellow when the speaker outputs are short circuited.
Fuses - When fuses blow, replace them with the same value. Never use a higher rated fuse !
(+12) Power Terminal - This is the main power input for the amplifier and must be connected directly to the posi-
tive terminal of the vehicles battery for proper operation. Use caution when installing (+12) power cable in the
vehicle. Avoid running this cable parallel with RCA cables, antennas, or other sensitive equipment due to massive
currents that can induce noise into the audio system. It is also very important to have a tight, secure connection
for maximum performance. MTX recommends using 21mm2 power wire with the MTX TH904 amplifier.
Remote Terminal – The amplifier can be turned on by applying 12 volts to this terminal. Typically this voltage is
supplied by a wire from the source unit marked "remote" or "power antenna".
Ground Terminal – A proper ground is required for your amplifier to operate at peak performance. A short ground
cable the same diameter as the power cable should be used to attach the ground terminal directly to the chassis
of the vehicle. Always remove paint, dirt or debris to expose bare metal where the ground will be attached.
Input Switch : If the head unit is equipped with 4 RCA outputs (2 front and 2 rear), use the 4ch mode and connect
the 4 RCA outputs to the 4 RCA inputs on the amp. If only 2 RCA outputs are available from the head unit, use the
2ch mode to feed the entire amp.
High level inputs
through RCA
Adaptors
included
To Head
Unit
Speakers
Installation & Mounting
MTX recommends your new Thunder amplifier be installed by an Autho-
rized MTX retailer. Any deviation from specified installation instructions
can cause serious damage to the amplifier, speakers and/or vehicles elec-
trical system. Damage caused from improper installation is NOT covered
under warranty. Please verify all connections prior to system turn on !
1. Disconnect the vehicle’s negative battery cable.
2. Determine the mounting place for your MTX THUNDER amplifier. Keep in mind there should be sufficient air flow for
proper cooling. Mark the mounting holes from the amplifier to be drilled. Before drilling make sure all vehicle wires, gas
lines, brake lines and gas tank are clear and will not interfere with installation. Drill the desired holes and mount the MTX
THUNDER amplifier.
3. Install a positive (+) power cable from the vehicle’s battery through the firewall using a grommet or firewall bushing to
avoid cable damage from sharp edges of the firewall. Run the cable through the interior of the vehicle and connect it to
the amplifier’s +BATT terminal. Do Not connect to the battery at this time.
Note : Use only proper gauge wire for both positive and negative connections.
4. Install a circuit breaker or fuse within 20cm of the battery. This effectively lowers the risk of severe damage to you or
your vehicle in case of a short circuit or accident. Make sure the circuitbreaker is switched off or the fuse is taken out of
the fuse holder untill all connections are made. Now connect your positive power cable to the positive battery terminal
of the battery.
5. Grounding - Locate a proper ground point on the vehicle’s chassis and remove all paint, dirt or debris to reveal a bare
metal surface. Attach the ground wire to that contact point. Connect the opposite end of the ground wire to the GND
terminal on the MTX THUNDER amplifier.
6. Connect a Remote Turn-on wire from the source unit to the MTX THUNDER amplifier’s Remote terminal. If the source
unit does not have a dedicated Remote Turn-on lead, you may connect to the source unit’s Power Antenna lead.
7. Connect RCA cables from the source unit to the MTX THUNDER amplifier’s RCA Bi-level inputs. Both low and high
level signals can be used. Run all signal cables away from vehicle wiring, computers and power cables. If cables must
be crossed do so at a 90° angle. Use only high quality twisted pair interconnect cables to decrease radiated noise from
entering the system.
• Using RCA Connections: Simply attach a signal cable from source units RCA outputs to the amp’s RCA inputs. This pro-
vides input signal to the amp.
• Using Speaker Level Connections : If the source unit does not have RCA outputs, high level signals can be used by tak-
ing the supplied high level RCA adapter and connecting it to the vehicle’s rear speaker wiring. Connect the left negative
speaker wire to the green and black striped wire on the high level RCA adapter. Connect the left positive speaker wire to
the solid green wire. Do the same for the right speaker connection using the purple wire. Now plug the RCA connectors
into the amp’s inputs.
8. Connect your speakers to your MTX THUNDER amplifier’s speaker terminals using the right gauge speaker wire. Both
channels bridged can drive a 4 ohm minimum load for max power.
9. Double check all previous installation steps, in particular, wiring and component connections. Once verified, reconnect
the vehicle’s negative battery cable, turn the circuit breaker on or place the fuse in the fuse holder.
Note : Gain Levels on the amplifier should be turned all the way down (counter clockwise) before proceeding with adjust-
ments.
Troubleshooting
Problem
Cause
Solution
No LED indication
No +12V at remote connection
Supply +12V to terminal
No +12V at Power connection
Supply +12V to terminal
Insuffi cient ground connection
Verify ground connection
Blown power fuse
Replace fuse
Power LED on, no output
Volume on source unit off
Increase volume on source unit
Speaker connections not made
Make speaker connections
Gain control on amplifier off
Turn up gain
Signal processing units off
Apply power to signal processor
All speakers blown
Replace speakers
Output distorted
Head unit volume set too high
Lower head unit volume
Amplifier gain set too high
Lower amplifier gain
Balance reversed
Speakers wired L + R reversed
Wire speakers with correct orientation
RCA inputs reversed
Reverse RCA input
Bass is weak
Speakers wired out of phase
Wire speakers with correct phase
Not using MTX woofers
Buy MTX woofers
Blowing fuses
Excessive output levels
Lower the volume
Amplifier defective
Return for service