A Power House In Slick Clothing - AUTOTEK 1400.1D Amplifier

Manual

Might as well just throw it away. Really. The manual covers 10 different amplifiers in only nine pages. It does give a very generic overview of the connectors and adjustments, but this same information can be read from the endplate of the amplifier. The "After Installation" setup and "Troubleshooting" sections are the only two pages worth reading when setting up the amplifier. Both sections are pretty generic but at least could help if you had a problem and wanted to isolate it before calling Maxxsonics for help or repair. Calling them does get a real person quickly and the website offers e-mail addresses for support as well as customer service and sales. These contact services are shared between all of the companies under the Maxxsonics umbrella, so be specific when communicating with them.

It is a shame that they included such a poor manual. There really isn't anything in there that will help you -- no mention of which gauge of wire to use or suggestions for wiring. The diagrams are inconsistent with the amplifier and the connection diagram for the RCAs is still leaving me scratching my head. Covering so many amplifiers, there is no room to enumerate the small things for each model like what fuses, how many and what current. However, the warranty was clear in its duration of one year, but what is covered under the warranty isn't clear.

Performance

A Class D amplifier which can easily drive 1-ohm loads at this power level is hard to find in this price category. And this one does it with ease. Making over 1,700 watts at a respectable 5% THD is asking a lot from this small package which is rated at a mere 1,400 watts (which it achieves under 2% THD). It performs just under 650 watts into 4 ohms at 1% THD distortion (CEA2006 specification), with 2-ohm power coming in nearly 100 watts over its 1,000-watt published specification. The highest efficiency was found to be 81 percent. Damping factor, however, measured a dismal 31.5.

Both thermal and short protection worked properly. There were no noticeable turn-on or -off sounds. The only real issue we found was the turn-on and -off time. We measured turn-on time at 6.2 seconds, nearly twice that of other amplifiers. Turn-off time was found to be 1/8 second, long enough for sounds from head units or EQs to propagate through to the speaker. Turn-off time was also load dependant, so there's no real way of saying what it will be in your system.

For a Class D amplifier it did test very well, with clean power well past its rated specification. Its performance was much better than older Class D designs that use cheaper chipsets. Of course, it still is not as clean as comparable Class A, A/B or G/H design; but with the super high efficiency of the Class D design, it makes a good bass amp, which is what was intended.

The 1400.1D served up no surprises in use. This amplifier hit hard and cleanly, forming a solid bass backbone in any car. With the bass boost EQ function, I was able to overcome some of the response shortfalls in my ported cabinet. When powering a good subwoofer, none of the deficiencies in the amplifier were audible. It fit right in as a good, high-power subwoofer amplifier.

Conclusion

In the end the Autotek 1400.1D performs and looks just like you would expect from the Autotek name. It is solid and heavy with very clean looks and sound. The controls allow it to be set up to perform in virtually any subwoofer context, and the addition of balanced inputs is a nice touch. We really like the mounting system for the power devices and the size of the fuses. And with over 80 percent efficiency, it is a really great choice for any space-constrained installation. The price is certainly nothing to balk at either. With an MSRP $1,000, it is well below the $1/watt standard, into the value arena of $0.71/watt. Pity about the manual though.

TEST RESULTS: AUTOTEK 1400.1D

OUTPUT POWER @1% THD, 100Hz, 14.4 VOLTSMono @ 4ohm620 wattsMono @ 2ohm1074 wattsMono @ 1ohm772 watts

OUTPUT POWER @ 5% THD,100Hz, 14.4 VOLTSMono @ 4ohm698 wattsMono @ 2ohm1190 wattsMono @ 1ohm1750 watts

OUTPUT POWER @ 1% THD,100Hz, 14.4 VOLTSMono @ 4ohm480 wattsMono @ 2ohm820 wattsMono @ 1ohm704 watts

Distortion at rated power, 100Hz, 14.4V1.4% 1 ohmEfficiency at 1/3 power, 1%THD, lowest impedance66.2%Efficiency at full power, 1%THD, lowest impedance69.9%Maximum Current Consumption170 amps@5%THD, 1750wattsInput Sensitivity200mV to 10VFrequency Response (+/-3db)12Hz - 250 HzS/N (A-weighted, 1-watt)-52dBADamping Factor@100Hz, 4ohms 25watts31.55Idle Current3.2ACrossover Slope24 dBCrossover Range35Hz - 250HzBass Boost0dB - 18 dB @ 45 HzSubsonic12Hz - 35HzDimensions14 1/4" x 10" x 2"

The power supply consists of dual transformers controlled by a single PWM chip to keep them in phase with each other. They easily supply the power the amplifier needs. Taking up nearly two-thirds of the interior there is still not a huge amount of capacitance on the input to the supply or on the outputs. Being a Class D amplifier and an unregulated supply, these are design decisions made solely on putting in what is needed for a strong, reliable product. This also keeps the size and price down, making this a relatively small amplifier considering that it produces nearly two kilowatts of power.

Amplification of what Autotek refers to as "Super D-Class" is carried out by a pretty standard Class D chipset, the HIP4080A. While this is a relatively new chipset for Class D amplification in the car audio market, it has been around for a number of years, so most of the bugs have been worked out of it. This has permitted Autotek to claim the benefits of its high-speed conversion, accuracy and low distortion. As stated by Autotek, "Super D-Class amplifiers offer higher current capacities and more precise digital to analog conversion, resulting in very low distortion levels, even at high listening levels. Super D-Class possesses a significantly greater efficiency rating than analog and lesser D-Class designs from our competitors." We'll see if these claims are true in just a bit.

The main power supply is not synchronized with the Class D switching portion of the amplifier. This doesn't affect the efficiency or performance of the amplifier, but it does lead to some odd effects if your speaker and enclosure have a large frequency-response range. For fun we did hook it up to a fullrange speaker, without any audio, and the difference in switching frequency from the supply and the Class D section make for a good science fiction sound effect. This is not a problem or an issue for an amplifier that won't be hooked up to a speaker with such a response, but a fun thing to try nonetheless.

The majority of the components in this amp are pretty generic. The frequency control pots use detents which some people like and others don't. The capacitors are really being pushed in this design -- now it won't really effect the performance, but I don't really like to see a large number of 85C electrolytic capacitors as the amplifier could exceed this temperature in places, creating a problem.