Since this beast is mostly power-supply, let's take a closer look at how it works. The B+ and Ground connect through 4awg set-screw terminal blocks. In turn, the B+ goes directly through a bank of six parallel 30-amp fuses, then through four parallel inductors to clean it up a little and proceeds to a pair of large litz-wound transformers. A single 3525A pwm controller running at 30kHz drives a total of 20 IRFZ44N switchers (5 pair for each transformer) for a total power dissipation of 1,880 watts at 25 degrees C. There are fourteen primary caps at 2200fd each for a total of 30,800fd on the 12volt side. Six 2200fd caps stabilize the 77voltrails, all caps rated at 105 degrees C.
The output section is the interesting part here. Most class D outputs use a single pair of output devices for each channel as I mentioned earlier. The outputs in a class D configuration are required to switch extremely quickly, historically very close to their limits. This switching speed limitation is what has restricted most class Ds to lower frequency ranges. The devices have not been particularly accurate at those high speeds, so it wasn't a good idea to arrange more devices in parallel to increase the power output. The potential for shorted outputs when two devices are not working together properly was too great. Some transistor manufacturers concentrated on higher power single devices, but some have developed more accurate, higher speed devices, which is what Lanzar is using in the Opti2000D to pass 2kW on to your speakers. There are 14 International Rectifier FB31N20D outputs, each capable of 200 watt dissipation at 25 degrees C. That's a total capacity of 2,800 watts, definitely overbuilt here! The output leaves by way of two 8awg terminals-the size of a normal amp's power terminals!
PerformanceThe frequency response measured 15Hz to 130Hz + 1dB. Lanzar shows 15Hz to 150Hz + 3dB, which I verified. There is a distinct hump at 43Hz (probably an artifact of the bass boost circuitry) even with the Bass Boost turned all the way down. Because of the narrow frequency scale of the graph it looks worse than it really is-the peak is less than 0.7dB.
At first glance, I thought the 4awg power connectors were small for a 2kW amp, but the unit proved to be very efficient. In the neighborhood of 80% efficient, the cable gauges are perfect, though I could not draw anywhere near the 180 amps that it is fused for. The amp puts out a lot of power, but seems to do it without breaking a sweat.
Overall the amp measured as advertised, with RMS power meeting Lanzar's spec and then some, though I could not duplicate the Max power at 0.5ohm load. The Crossover and Subsonic Filter were right on the stated ranges with nice clean slopes, although the slopes were closer to 22dB/octave than 24dB as stated. The amp was pretty noisy on the bench but remember, with gain comes noise, and this amp has lots of gain. S/N and Damping Factor measured lower than spec (see specifications).
The crossover measured 22dB/octave, from 48 to 155Hz, close to Lanzar's specs of 24dB/octave, 50 to 150Hz. The subsonic filter measured 22dB/octave, 14 to 56Hz-a little off of Lanzar's specs of 24dB/octave, 15 to 40Hz. Like the crossover, the bass boost was pretty close to spec with a maximum of +19dB boost at 43Hz. Both the short circuit and overload protection worked well; the amp recovers automatically from a brief short-circuit, but extended short circuits (5 seconds or more) require turning the amp off and back on to reset. I could not heat this amplifier sufficiently to trigger the thermal protection, and believe me I tried. Hey, efficiency is your friend.
There was no turn-on noise, but the amp puts out enough noise to tell when it is on, even with the gain turned down. Turn-off consistently generated a sharp pop.
Owner's ManualThe owner's manual was not written with the novice in mind. Installation instructions are definitely for installers that already know what they're doing, using phrases like "Make sure there is sufficient air flow around the intended mounting location" and "further fine tuning of the various controls may be necessary to obtain the desired results." There is no mention at all of connecting the speaker wires in this section. The diagrams and pictures are good, clearly showing connections and how to bridge two amplifiers to a single speaker, but again the manual fails to explain the main features and how to correctly set them. The amplifier carries a three-year warranty.