25 June 2013
Firmly established as a respected brand, Memphis Car Audio has been getting even more serious about delivering high-performance, top-quality products. Whether you are an SPL enthusiast or a sound quality geek, they have products to suit your needs and personal tastes. When it comes to amplifiers, the 16-MJ1.2200 is the top-of-the-line Memphis M-Class MOJO amplifier. Rated at 2,200 watts into one ohm and carrying an MSRP price of about $1,399, this is a serious piece of hardware. There are rumors of an even more powerful model in the works.
The entire line of M-Class amplifiers have been completely re-vamped for 2013, featuring a plethora of cool and useful features. Attributes like top-mounted concealed controls, impedance-compensated clipping indicators and remote level controls are found on all models. The heatsinks are all-new and the redesign uses more mass than previous models. The entire amplifier chassis is formed from two robust extruded aluminum pieces; in fact, the only thin sheet metal pieces on these amps are the end panels. Removable aluminum end caps cover the wiring connections and provide a clean finished look. The top-mounted controls are covered by a backlit, removable badge held in place by four small hex head screws. The logo can even be rotated in 90° increments so it is properly oriented for every installation.
With a length of about twenty one inches and a width of nine inches, the 16-MJ1.2200 isn’t a small amplifier, but when you consider the power it produces, many people will be surprised it’s not bigger.
The layout is pretty normal for this type of amplifier, with the power and speaker connections on one end, and the small signal inputs and connections on the other. Power terminals will accept 1/0 cable, and a 250A mini AGU fuse is mounted under a nice cover between the power and speaker terminals. A good indication that the designers meant serious business is the speaker terminals, which accept up to 4-gauge cable. On the other end, you’ll find panel-mounted RCA connections for input and pass-through signal outputs, a pair of bridge connectors for an additional amplifier, the Memphis Distortion Analysis Control or “MDAC,” and the RJ45 connector for the Memphis Total Level Control or “MTLC.” A small yellow LED, labeled “MDAC Status,” will light up as the amplifier approaches clipping. To make sure the LED retains accuracy (regardless of the load impedance), a switch is provided to set the LED indicator’s accuracy for four, two, or one ohm loads.
Under the removable top badge are the adjustment controls for gain, -24 dB low-pass crossover (50 Hz to 250 Hz), -24 dB infrasonic filter (20 Hz to 50 Hz), and bass boost, which is good for up to 14 dB of boost at 45 Hz.
Taking the 16-MJ1.2200 amplifier apart, I find more evidence of heavy-duty engineering. The amp gets its output current from a pair of large toroids which are switched by sixteen International Rectifier, high-current MOSFETS, each capable of switching 100A. Power supply capacitance totals 52,800µF, thanks to sixteen high-speed, high-temperature capacitors. On the output side, the musical signal is driven by fourteen IR2N20D MOSFETs with a total current capability of over 600 amperes. The PCB is a heavy-duty, double-sided affair, primarily using surface-mount, low-tolerance parts for exacting performance.
After unpacking and inspecting the amp to make sure I understand the controls and connections, I hook the Memphis amp into my reference system and connect it to a pair of four-ohms, twelve-inch woofers wired in parallel so the final impedance is a two-ohms load. After adjusting the crossover and gain controls, I sit down with a fresh mug of what my friends refer to as “Cogent coffee,” and begin the listening session.
Starting off with recordings from the Telarc and DMP labels, which allow me to judge the amplifiers ability to produce details and bass articulation, I find that deep or synthesized bass doesn’t strain or lack any current. The detail and articulation in these well-recorded tracks is reproduced with very good clarity and definition. Eventually I move to some hip hop and rap tracks from Nine Inch Nails, 50 Cent, and Jay Z, then some well-recorded country tunes. Regardless of my musical choices, the 16-MJ1.2200 handles it all assuredly at virtually any listening level. With plenty of power on tap, I can simply turn it up as loud as I like and the M-Class amp will deliver.
The crossover and subsonic filters work as intended and the bass boost is available if I need more low end – but with this much power available, I don’t.
When compared to other Class-D amplifiers I have recently auditioned, the 16-MJ1.2200 certainly delivers in terms of power and sonic performance. The amplifier barely even got warm when played continuously at moderate to high levels for a couple of hours, so I expect my bench measurements will confirm it is pretty efficient.
On the Bench
The next day, I connect the 16-MJ1.2200 to my trusty Audio Precision and measure the actual performance specs. As I expect from my listening session, the amp measures well and easily exceeds its published performance numbers. It actually makes significantly more power than advertised, indeed proving to be a very efficient design.
The following power measurements were obtained using industry standard methods. (1 kHZ @ 1.0 % THD+N - Battery voltages shown +/- 0.2 V)
Measured Performance Specifications
Manufacturers Rated Power Actual Measured Power
@ 1.0 % THD+N @ 12.6 V Battery Actual Measured Power
@ 1.0 % THD+N @ 14.4 V Battery
800 x 1 @ 4 Ohms 735 x 1 @ 4 Ohms 960 x 1 @ 4 Ohms
1500 x 1 @ 2 Ohms 1290 x 1 @ 2 Ohms 1683 x 1 @ 2 Ohms
2200 x 1 @ 1 Ohms 1947 x 1 @ 1 Ohms 2600 x 1 @ 1 Ohms
Signal to Noise Ratio referenced to 2V output.
(CEA-2006A) (1 watt @ 4 ohms) -74.4 dBA
Signal to Noise Ratio referenced to full 4 ohms output. -104.2 dBA
THD+N at rated 4 ohms power 0.28 %
CEA-2006A rated 4 ohms Power (minimum power per channel developed over the entire intended audio bandwidth) 950 watts
Maximum Efficiency at full 2 ohms power per ch. 85.2 %
Idle Current 2.2 A
Input Sensitivity 165 mV- 9.3 V
Maximum Current @ full power, lowest rated impedance 244.5 A
Frequency Response (-3 dB) 21 Hz – 268 Hz
Subsonic (High Pass) Crossover 21Hz – 54 Hz -24dB/oct
Low Pass Crossover 55 Hz – 268 Hz -24 dB/oct
Bass EQ boost +14 dB @ 46 Hz
Phase Adjustment (degrees of shift @ 100 Hz) N/A