Amplifiers for boats, motorcycles or side-by-sides are plentiful, but few can match the performance and reliability of the M5-Series from Rockford Fosgate. Our previous encounter with the M5-1000X1 left us in awe, and now we have the four-channel M5-800X4 Class-AD full-range amplifier in our lab for a comprehensive Test Drive Review. Let’s delve into its unique features and see what sets it apart!
Rockford Fosgate M5-800X4 Specifications
Let’s start by looking at the M5-800X4’s specifications. Rockford Fosgate rates this amplifier as capable of producing 100 watts from each of its four channels into 4- or 2-ohm loads. When in a bridged configuration, the amp can deliver 200 watts into a pair of 4-ohm loads. Frequency response is specified as 10 Hz to 50 kHz, and efficiency is greater than 75%. The amp can accept signals up to 12 volts on the RCA input jacks, allowing this amp to connect directly to the output of most factory-installed radios.
In terms of audio features, the amplifier includes separate front and rear, high- or low-pass crossovers that are adjustable from 50 to 250 Hz. The slope is specified as -12 dB/octave. Each pair of channels also has its own Punch EQ control. Your installer can crank this to add up to 18 dB of boost at 45 Hz and 14 dB boost at 14.5 kHz to overcome the noise floor found in most vehicles.
Each pair of channels is equipped with Rockford Fosgate’s C.L.E.A.N. setup circuit that helps simplify the calibration process. This feature includes LEDs on the top panel that blink when the input signal has been optimized and when the amp reaches its maximum output capabilities. This feature eliminates the need for scopes, multimeters or distortion measurement devices when configuring the system.
Designed for the Harshest Conditions
One of the features that separates the M5-800X4 from many competing products is its Element Ready design. In the case of this amp, the unit has an IPX6 rating, meaning it can withstand a high-pressure water stream from any angle without concern of water infiltration and damage. The Element Ready moniker also includes UV exposure testing, so the amp will continue to look great, even if exposed to the sun for years. If you happen to live by or play on the ocean, the amp has been designed to resist corrosion from salt spray.
Finally, and crucially, Rockford Fosgate subjects its Element Ready products to vibration testing. You can be confident the components in the amp won’t rattle loose or fail when used on a big Harley-Davidson with a lumpy cam or on your boat as it crashes across the waves. Few other companies consider vibration and impact testing in their product design process.
Physical Design and Layout
The M5-800X4 measures 8.41 by 4.25 inches, not including the signal and power harnesses. The amp stands a mere 1.7 inches tall but weighs a hefty 4.19 pounds. This mass isn’t there by accident. Rockford Fosgate is well known for its MEHSA 4 (Maximum Efficiency Heat Sink Application) designs, allowing its products to play longer than most other solutions. Keeping the temperature of the internal components in check is critical to the product’s longevity. Have you ever wondered why people still use Punch and Power series amplifiers from the ’80 s?
On the top-left side of the amp is a removable panel that conceals and protects the controls. As mentioned, each channel has a level, crossover frequency and Punch EQ control. There’s a three-position switch to change the crossover’s function from full range to high or low-pass. There’s also a “PRESET” switch for each pair of channels. When used with one of Rockford Fosgate’s SXS audio kits, enabling this switch takes care of all the configuration, saving the installer time. A switch also routes the signals from the front inputs to the rear to simplify the installation process.
As mentioned in the M5-1000X1 review, attention to detail is everywhere in this amplifier. After machining the opening for the controls, Rockford Fosgate adds brass nut inserts to ensure the cover can be removed and reinstalled repeatedly without fear of the threads wearing out.
The left end of the amp has a water-resistant connector with wire pigtails and two four-pin Molex connectors. The amp includes a pair of RCA input cables and a pair of wire pigtails for use with high-level signals. Of course, the inputs feature balanced differential circuitry, so you don’t need a line-output converter to deal with BTL amplifiers. Further, the M5-800X4 has signal sense and DC offset remote turn-on circuitry, making integration with factory audio systems even more accessible.
The other end of the amp has a larger water-resistant connector that accepts power, ground and remote turn-on connections. It also has a pair of speaker output pigtails, each with its own four-pin Molex connector. A custom-tooled terminal block makes it easy for your installer to get the amp wired into your vehicle or boat. The block will accept freshly stripped 8 AWG power and ground cables.
Rockford Fosgate uses this amp in several motorcycle and UTV audio kits. The Molex connectors on the inputs and outputs keep the wiring process simple and straightforward in those applications.
Auditioning the Element Ready M5-800X4 Amplifier
Let’s investigate the M5-800X4’s performance by setting it up in the labs’ reference system. The front channels drive a set of 2.5-way bookshelf speakers, and the rear channels are bridged to a 12-inch subwoofer in a sealed enclosure. The CD player handles frequency filtering, which is set at 80 Hz with 18 dB/octave filters.
The first track I auditioned on the M5-800X4 was “Into My Arms” by Nick Cave from the album The Boatman’s Call. Spatially and tonally, the amp sounded magnificent. The soundstage was big, and the voices and instruments were well focused. If I strained really hard, there might have been a bit more emphasis in the upper midrange. The speakers you use with the amp will have 100 times more effect on what you hear.
Next, I listened to “The Peppery Man” by Natalie Merchant. This track includes Isaac Freeman and Joe Rice on vocals. Natalie’s vocals were again slightly forward, but the difference was less than a decibel or so. The gentlemen have impressively deep voices, giving the speakers a workout. Everything stayed clear and controlled with no issues.
The last track I auditioned was “Angel” by Massive Attack. I cranked the volume up a fair bit on this one. This track has a good bass beat centered at just above 40 Hz. This proved to be a bit more of a challenge for the M5-800X4. The beat was clear but not as defined as with my reference amp. Of course, you’d expect some difference in performance for something that costs three times as much. One of the full-size Power Series amps would work if you need that impact. However, that isn’t going to fit in the fairing of your motorcycle or under the dash of your side-by-side.
Overall, the amp sounds magnificent. The focus was excellent, and the soundstage width was on par with some of the better amps I’ve auditioned. There was no audible hiss to detract from the listening experience, and the amp started up and shut down silently.
Bench Testing the Rockford Fosgate M5-800X4
After completing the listening tests, I brought the amp to the test bench to start with the performance measurements. I always start with low-power tests for frequency response and harmonic distortion.
Starting with the amp driving a set of 4-ohm load resistors, I measured THD+N at the industry standard output level of 1 watt. The M5-800X4 added 0.01826% THD+N with a noise floor of -84.04 dB. This is a solid performance.
The next test was to measure frequency response. With the crossovers off, I referenced the amp to 0 dBV at 1 kHz and performed a sweep from 1 Hz to 96 kHz. I repeated the tests with the amp driving 4- and 2-ohm resistive loads and my reactive 4-ohm circuit. On the bottom end, the amp was flat down to 2 hertz. On the top, the Class D output filter caused a resonance that made it hard to specify a specific frequency. However, the graph shows the amp will easily extend beyond 20 kHz with no significant attenuation. Know that this is typical behavior for Class D style amplifiers and isn’t an issue specific to this device.
Interestingly, the response is flattest when driving the reactive load. This highlights the know-how of Rockford Fosgate’s engineering team. Designing an amp to behave well when driving real-world reactive loads (like speakers) differs significantly from driving resistors. Kudos!
The second last set of tests was to measure power. Rockford Fosgate rates the amp as capable of continuously producing 100 watts of power into 4-and 2-ohm loads from all four channels and 200 watts into a pair of 4-ohm loads when bridged. In my testing, the amplifier exceeded its rated power in all tests, even when supplied with significantly less than the 14.4 supply voltage.
As a side note, I have purchased a new power supply to provide all the amps that come through the lab with exactly 12.5 and 14.4 volts. I’m waiting for the electrician to wire a 230-volt outlet to the bench, so you’ll see that change/upgrade in future Test Drive Reviews. I can hear the chants of “Hallelujah!” already!
The last test is one that many consumers fail to consider when buying an amplifier. This test evaluates the design of the heatsink and the amplifier efficiency – critical factors when you want to push an amp to its limits for long periods. I configured the amp with a 2-ohm load on each of the four outputs and ran it at maximum power until I got bored. The M5-800X4 ran for more than 40 minutes before I aborted the test. To put this into perspective, I’ve measured amps rated for similar output levels that would overheat and shut down in under three minutes.
Overall, the M5-800X4 performed just like the other Rockford Fosgate products that have visited my test bench, which is to say, it’s excellent. The output signal is clean, and the amp has no problem repeatedly going from 0 to full power. It offers good efficiency and impressive thermal stability, which are crucial to ensuring that the amp keeps playing for years.
Conclusions on the M5-800X4 Element Ready Amplifier
There are probably too many compact amplifiers on the market these days. If you want something that sounds great and performs reliably, the list of options is pretty short. For motorcycle, marine and powersports applications where exposure to dust, dirt, water and intense vibration matter, the Element Ready M5-Series of amplifiers from Rockford Fosgate stands out from the rest. Based on my listening evaluation and lab testing, the M5-800X4 sounds impressive, measures well, behaves fantastically and offers excellent reliability. You can’t go wrong with this for your powersports application.
Drop by a local Rockford Fosgate retailer today and ask about the M5-Series Element Ready amplifiers from Rockford Fosgate. You can find a retailer near you using the locator tool on their website. Follow them on Facebook, Instagram and YouTube to learn about their latest product releases and find coverage of events they attend.
