85 Watts RMS x 4 for Full-Range Speakers
The four primary channels provide 85 watts RMS each at 2 ohms.
That’s considerably more output than most factory head units can deliver directly to the speakers and makes the SK-M9005D suitable for powering compatible aftermarket coaxial or component speakers.
When selecting speakers, compare:
- Speaker RMS power handling
- Speaker impedance
- Amplifier RMS output
- Speaker sensitivity
- Crossover requirements
Don’t match equipment solely by peak-power ratings.
Continuous RMS power provides a much more useful basis for designing an audio system that works properly once everything is installed.
Dedicated 450-Watt RMS Subwoofer Channel
The fifth channel provides up to 450 watts RMS at 2 ohms for a compatible subwoofer system.
This allows the amplifier to provide substantially more power to the subwoofer than to the cabin speakers, which makes sense given the greater power generally required to reproduce low frequencies at useful output levels.
A 450-watt RMS subwoofer channel can work well with many single-subwoofer installations when impedance and continuous power handling are properly matched.
Before purchasing a subwoofer, determine its final wired impedance rather than looking only at the impedance printed on the product name.
One Amplifier for Speakers and Bass
The five-channel architecture is the defining advantage of the SK-M9005D.
A conventional system can use one amplifier for:
- Front component speakers
- Rear coaxial speakers
- Dedicated subwoofer
That can simplify the installation considerably compared with separate four-channel and monoblock amplifiers.
Benefits can include:
- Less mounting space
- Fewer power connections
- Fewer ground connections
- Simpler signal routing
- Reduced wiring complexity
- Cleaner amplifier installations
- Easier troubleshooting
Our car audio system guide goes deeper into matching speakers, amplifiers and subwoofers when planning a complete aftermarket system.
Ultra-Compact Class D Design
One of the strongest features of the Skar Audio SK-M9005D is its physical size.
The amplifier measures approximately:
12.4 inches long
4.6 inches wide
1.7 inches high
That’s an unusually narrow footprint for an amplifier capable of powering four speakers and a subwoofer.
The compact chassis creates more potential mounting options, including:
- Under seats
- Behind rear seats
- Inside compact trunk panels
- Beneath false floors
- Behind interior trim
- Within custom amplifier racks
Measure the available space before installation and remember to account for wiring clearance and ventilation.
Apparently an amplifier can be compact without requiring the installer to remove the spare tire, rear seat and half the trunk. Progress.
Efficient Class D Amplifier Architecture
The SK-M9005D uses Class D amplifier technology.
Class D amplification is well suited to compact automotive installations because it can produce substantial output with relatively high electrical efficiency.
Greater efficiency means less input power is converted into unwanted heat compared with less efficient amplifier architectures.
Benefits include:
- Smaller amplifier chassis
- Reduced heat generation
- High output for the physical size
- Lower electrical demand relative to output
- Greater mounting flexibility
Proper cooling still matters. Efficient does not mean immune to heat.
MOSFET Power Supply
Skar Audio uses a MOSFET power supply in the SK-M9005D.
The power supply converts the vehicle’s electrical input into the internal voltages required by the amplifier circuitry.
This is particularly important in a five-channel design because the amplifier may simultaneously be reproducing vocals and midbass through four speakers while delivering significant low-frequency output to the subwoofer.
Stable vehicle voltage and quality power connections help the amplifier maintain consistent operation under load.
Full-Range Channels Cover 10 Hz to 20 kHz
Skar Audio specifies a 10 Hz–20 kHz frequency response for channels 1–4.
These channels are intended for full-range audio reproduction and can be configured for a variety of compatible speaker systems.
The actual frequencies sent to the speakers should still be limited using the amplifier’s crossover controls according to the capabilities of the connected drivers.
Just because an amplifier can send very low frequencies to a door speaker doesn’t mean the door speaker has volunteered for the assignment.
Dedicated Subwoofer Channel Covers 10 Hz to 500 Hz
Channel 5 has a specified frequency response of 10 Hz–500 Hz.
This channel is designed specifically for bass applications and provides the output necessary for a compatible subwoofer.
The adjustable low-pass crossover can be used to prevent higher frequencies from reaching the subwoofer, helping it integrate properly with the main speakers.
Adjustable High-Pass Filter
The SK-M9005D provides high-pass filtering for the full-range speaker channels.
A high-pass filter blocks frequencies below the selected crossover point.
This is particularly useful for door speakers because deep bass can cause excessive cone movement without producing useful output.
Correct high-pass filtering can:
- Reduce speaker distortion
- Improve midrange clarity
- Reduce unnecessary cone excursion
- Increase usable speaker output
- Improve system integration
- Help protect smaller speakers
Once a dedicated subwoofer is handling deep bass, there’s generally little reason to ask smaller cabin speakers to attempt the same job.
Full-Range Crossover Mode
The amplifier also provides a full-range crossover setting for applications where external crossover networks or other signal-processing equipment handle frequency division.
This adds flexibility for custom installations.
When using full-range mode, make sure the connected speakers or external crossovers provide the necessary frequency protection.
Low-Pass Filtering for the Subwoofer
The dedicated subwoofer channel provides low-pass crossover control.
A low-pass filter removes frequencies above the selected crossover point, allowing the subwoofer to concentrate on bass.
Proper LPF adjustment helps prevent vocals and other higher-frequency information from becoming audible through the subwoofer.
The goal is for bass to integrate naturally with the main speakers rather than sound like somebody locked a drummer in the trunk.
Adjustable Bass Boost
The SK-M9005D provides bass boost adjustment for additional low-frequency tuning.
Bass boost can emphasize selected low frequencies, but it should be used conservatively.
Significant boost requires substantially more amplifier power at the affected frequencies.
Too much boost can contribute to:
- Clipping
- Distortion
- Excessive subwoofer excursion
- Amplifier heat
- Reduced headroom
Configure gain and crossover settings first, then make smaller bass adjustments after the system is operating correctly.
Remote Bass Knob Included
Skar Audio includes a remote bass knob and cable with the SK-M9005D.
The remote can be positioned near the driver’s seat, allowing the subwoofer level to be adjusted without accessing the amplifier.
This is useful when switching between recordings or genres with dramatically different bass content.
The remote should be used for reasonable adjustments after the amplifier gain and crossover settings have been established.
Speaker Output Adapter Harness Included
The SK-M9005D also includes a speaker-output adapter harness.
The harness helps simplify the physical connection of the amplifier’s speaker outputs while maintaining the compact dimensions of the chassis.
This is particularly useful when packaging five amplified channels into an amplifier only 4.6 inches wide.
Follow Skar Audio’s wiring identification carefully during installation to ensure correct speaker polarity and channel assignment.
Four-Way Protection Circuitry
Skar Audio equips the SK-M9005D with integrated four-way protection circuitry.
The supplied specifications list protection for:
- Thermal conditions
- Voltage problems
- Speaker faults
- DC conditions
These protection systems help safeguard the amplifier when abnormal operating conditions occur.
Protection mode shouldn’t be considered normal operation.
If the amplifier repeatedly shuts down, diagnose the cause rather than repeatedly cycling the power and hoping electricity changes its mind.
Prevent Thermal Problems
The amplifier’s compact chassis makes mounting flexibility one of its major advantages, but don’t install it where airflow is completely restricted.
Common causes of amplifier overheating include:
- Incorrect speaker impedance
- Restricted ventilation
- Excessive gain
- Clipping
- Low supply voltage
- Poor grounding
- Loose electrical connections
Our guide explaining why car amplifiers overheat covers the most common electrical and installation problems that can trigger thermal protection.
8-Gauge Power and Ground Inputs
The SK-M9005D uses 8-gauge power and ground input terminals.
Proper power wiring is critical because the amplifier needs a stable electrical supply to produce its rated output.
The installation should include:
- Properly sized power cable
- Matching ground cable
- Battery-side fuse
- Quality fuse holder
- Secure terminals
- Suitable speaker wiring
- Proper signal wiring
Always follow Skar Audio’s installation requirements when selecting cable and fuse sizes.
Power Cable Length Matters
Wire gauge isn’t the only factor affecting amplifier power delivery.
Cable length also matters.
Longer cables create greater resistance, which can increase voltage loss under load.
This is why amplifier wiring should be sized according to both:
- Current demand
- Cable length
Avoid undersized wiring even if the amplifier appears to operate normally at low volume.
Electrical problems often become obvious only when output and current demand increase.
Ground the Amplifier Properly
A poor ground can cause a surprising number of car audio problems.
Symptoms may include:
- Reduced output
- Amplifier shutdown
- Electrical noise
- Excessive heat
- Voltage instability
- Protection-mode activation
Use an appropriately sized ground cable and a suitable low-resistance chassis connection.
Keep the ground connection reasonably short and mechanically secure.
Test Voltage Under Load
If the amplifier shuts down or distorts when bass output increases, measure voltage directly at its terminals while the system is operating.
Potential sources of voltage loss include:
- Battery connections
- Fuse holders
- Power cables
- Ground connections
- Crimp terminals
- Distribution blocks
Our automotive voltage-drop testing guide explains how testing a circuit while current is flowing can expose resistance that a simple continuity test may not reveal.
The same technique is extremely useful when diagnosing amplifier power problems.
Set Amplifier Gain Correctly
Gain controls match the amplifier’s input sensitivity to the source signal.
They are not additional volume controls.
Excessive gain can drive the amplifier into clipping prematurely.
Clipping can cause:
- Distortion
- Excessive heat
- Reduced sound quality
- Speaker damage
- Subwoofer damage
Start with a clean source signal and configure gain methodically.
Afterward, set the crossovers and fine-tune the bass response.
Match Speakers by RMS Power and Impedance
The SK-M9005D provides 85 watts RMS x 4 plus 450 watts RMS x 1 at 2 ohms, so connected speakers and subwoofers should be selected accordingly.
Compare:
- Amplifier RMS output
- Speaker RMS power handling
- Speaker impedance
- Subwoofer RMS rating
- Subwoofer voice-coil configuration
- Final subwoofer impedance
Matching components this way produces a far more useful system than comparing peak-power numbers.
Great for Compact Performance Cars
The SK-M9005D is particularly interesting for vehicles where space is already limited.
Examples include:
- Sport compact cars
- Coupes
- Roadsters
- Compact pickups
- Performance sedans
- Custom interiors
Instead of consuming valuable cargo space with two large amplifiers, the SK-M9005D can handle the primary speakers and subwoofer from one narrow chassis.
That leaves more room for important automotive essentials—tools, detailing supplies and the collection of random parts you swear you’re going to install next weekend.
Useful for Stealth Audio Installations
The narrow chassis also lends itself to stealth audio installations.
An amplifier hidden beneath a seat or behind interior trim can preserve the factory appearance of the vehicle while substantially increasing available audio power.
This approach works particularly well for enthusiasts who want upgraded sound without building an obvious show-style amplifier rack.
Just make sure the hidden mounting location still provides adequate ventilation and service access.
Key Features
- Skar Audio SK-M9005D
- Ultra-compact five-channel car amplifier
- Class D architecture
- MOSFET power supply
- 900 watts RMS total output
- 85W RMS x 4 + 450W RMS x 1 at 2 ohms
- Ratings specified at 14.4V
- 10 Hz–20 kHz response on channels 1–4
- 10 Hz–500 Hz response on channel 5
- HPF crossover control
- Full-range crossover mode
- LPF crossover control
- Adjustable bass boost
- Dedicated subwoofer channel
- Remote bass knob included
- Remote bass cable included
- Speaker-output adapter harness included
- Four-way protection circuitry
- Thermal protection
- Voltage protection
- Speaker protection
- DC protection
- 8-gauge power and ground terminals
- 12.4 x 4.6 x 1.7-inch chassis
- Designed to power four speakers and a subwoofer from one amplifier
Big Five-Channel Performance from a Small Amplifier
The Skar Audio SK-M9005D Compact 5-Channel Class D Amplifier is designed for car audio systems that need substantial output without sacrificing installation space.
Its rated 85 watts RMS x 4 plus 450 watts RMS x 1 at 2 ohms provides a practical balance between full-range speaker power and dedicated subwoofer output. With up to 900 watts RMS total, one amplifier can handle a complete front-and-rear speaker system plus bass.
Adjustable HPF and LPF crossover controls help divide frequencies between the speakers and subwoofer, while bass boost and the included remote bass knob provide additional low-frequency control. Four-way protection circuitry adds safeguards against several common electrical and thermal problems.
Most importantly, Skar packages all of this into a chassis measuring only 12.4 inches long, 4.6 inches wide and 1.7 inches high.
For a performance car, daily driver or truck where mounting space is precious, the SK-M9005D provides a clean way to build a complete amplified audio system without turning the cargo area into an electronics department.
There are no reviews yet.