Rotel RA-03 Amplifier
The amplifier is analog, the main nodes are assembled according to the classical scheme on discrete elements. Judging by the marking, the resistors are low-noise; the capacitors are film, there are separate ground spikes for signal and power circuits. Bipolar transistors are used in the output stages. Their maximum current is 12 A, and there are two transistors in each arm, so the current reserve is quite decent. Microcircuits can be found only in some input stages. The inputs are fitted with Burr-Brown operational amplifiers, and the input switch is implemented on a specially designed Toshiba electronic switch consisting of a set of keys on complementary metal oxide semiconductors (CMOS). This switch allows to do without the use of expensive relays (reed switches). Proponents of the latter believe that the purely mechanical contact provided by reed switches is completely "decoupled" from the control electronics and does not introduce any distortions into the connection. It is easy to object to this argument: the signal already undergoes a lot of electronic transformations, and CMOS-key is almost similar to an ordinary resistor, and is not able to distort the signal form, and its reliability, at least, is not lower than that of reed switches. The radiators are located in the middle of the case, which promotes uniform air circulation.
Many entry-level and mid-level amplifiers allow the connection of loudspeakers with just a stripped wire, for which a cross hole is made in the screw terminal. This connection is simpler - there is no need to put extra pins on the wire. However, Rotel does not approve of this approach, and the RA-03 has no hole. This obliges the wire to be terminated with terminating contacts (of the "spade" or "banana" type). This should not be neglected. Let us follow the principle "haste and quality are incompatible". After all, no one will come to mind as laces for expensive shoes to use, say, packing twine.
The functional set is quite extensive: four line inputs plus an input with a built-in corrector for a "vinyl" turntable by means of a moving magnet (MM) cartridge. Another input (Tape) is for controlling the quality of the tape recorder. It is connected by turning a separate monitor knob, allowing you to compare the original signal with the recorded signal (of course, this is only possible for a tape recorder with a loop-through channel). The signal selected with the input selector goes to the recorder. Like most stereo amplifiers, the RA-03 is equipped with both a line output for recording and an output from the preamplifier. The difference between these outputs is that the latter signal reflects all your volume, tone and balance adjustments, while the line output keeps the source signal unchanged.
The RA-03's tone control range is only ±6dB - a common figure for a high-quality amplifier. Tones in this case are not used for gross changes in sound coloration, but for so-called tone correction - using them to track changes in the human ear's sensitivity to low and high frequencies at low volume. The special circuits used for this purpose usually have a fixed degree of compensation, which is suitable for only one volume level, so the RA-03 has no such circuits. But there is an option to disable timbres, eliminating their effect on the sound. The RA-03 is also equipped with current and thermal protection systems, the activation of which is signaled by the LED on the front panel.
One of the advantages of stereo amplifiers over multi-channel AV receivers is their ease of control and setup. This fully applies to the RA-03 as well. True, not all functions are available with the remote, but only the source selection, volume control, and power on option. The extended remote is also designed to control the basic functions of the tuner and the Rotel CD or DVD player, provided that these devices are connected together by a control bus. Like most stereo amplifiers, the RA-03 has no digital volume indication, but the bar LED on the Volume control makes it easy to scope out the set level even in the dark.
Subjective evaluation of the sound usually involves comparing what you hear with the class (and price) of the model. Therefore, the RA-03 was subjected to the most stringent requirements. The model does well both emphasizing bass and "tight" with the speakers. The former paired with the RA-03 sounds great thanks to the good damping qualities of the unit. Speakers of low sensitivity it rocks quite easily - it gives itself the power, though not a record, but for our apartments is quite sufficient. The amplifier creates quite a wide sound stage, the instruments of the orchestra try to arrange evenly, though sometimes it seems that some of them want to stand a bit closer to the dowels. In the upper frequencies the sound is clear, the triangle ringing is crystal clear, but its exact localization and not always unambiguous. Nevertheless, the ease of sound and its purity allow us to safely recommend the RA-03 to the most picky audiophiles.
