What is stereo?




There are now two system of high fidelity, monophonic (monaural) and stereophonic. Monophonic is a system that starts from one microphone and is fed through a single high fidelity set. Stereophonic is a double system. Two separate microphones are placed at different sides of the orchestra and two different systems are used to keep the two signals or channels separated. Two separate speakers are used, placed on different sides of you room. Stereo is much like 3-D photography, two slightly different sound reach your ears giving you a new dimension in sound.




H.H. Scott '59





Rotel RA-2030 (1978)

ROTEL RA-2030

Stereo Class AB Integrated DC Amplifier

less than 0.01% total harmonic distortion at a rated output

Class AB

DC configuration

INcorporates the same MC head amp as The RA-2040 into its own top level functions - an integrated amplifier incorporating the maximumfunctions of its class

Avery clean amplifier

DC CIRCUITRY

The RA-2030 uses DC amplifiers with excellent response at very low frequencies and makes maximum use of its DC circuitry design. As is becoming standard in precision equipment, Rotel's DC amps have eliminated all capacitors ( which give unwanted time constant) from the signal path and the negative feedback loop, stabilized the DC range and greatly improved transmission characteristics, enabling superior low frequency performance.

On the other hand, negative aspects of DC circuitry such as DC drift due to fluctuations in input and in power supply have been eliminated in the 2000 series by stabilizing the differential's mid-point electric potential, using circuit technology to achieve a DC balance, and securing an adeguate CMRR (Common Mode Rejection Ratio) value. As a result, the audio enthusiast is even free to enjoy the full dynamic range of organ music, with all its low frequency signals.

CLASS AB OPERATION

In general the biggest drawback to Class A amplifiers, which have no switching and crossover distortion is their low efficiency. Rotel, however, employs a new system that maximizes the superior sound quality of Class A amps while at the same time ensuring maximum output. Class A operation which is amazingly distortion free and provides excellent sound quality when listening to regular music, automatically switches over to Class B operation when more power is required by a large signal. By adopting this ideal system, where Class A operation handles average music signals and Class B ensures a broad dynamic range during peak signals, the 2000 series Class AB philosophy proves its true worth distortion is held below 0,01% even during maximum output (Class A operation below 5 watts as previously mentioned are remarkably distortion free).

SOPHISTICATED PROTECTION CIRCUITRY AND OVERLOAD INDICATOR

The 2000 series uses 3 sets of protection circuitry to protect both the amp itself and the speakers from possible overload damage. One is electronically controlled ASA (area of Safe Operation) detecting circuitry that employs a relay to protect the output transistors and the speakers in case of accidental overload. The second is a DC feedback power limiting circuitry taht serves to protect the transistors when impedence load falls below 4 ohms. The Overload Indicator light located on the front panel of the amplifiers informs the user when the above circuitry goes into operation. The third is the separate relay which overcomes the problems of loud pop-noise and abnormal in-rush current when turning the power switch on.

MC HEAD AMPLIFIER

The RA-2030 both use a low noise FET differential amplifier for the input stage and a 3-stage parallel-coupled circuit for the output stage. WIth a built-in MC head amp it becomes possible to enjoy music without having to use an external headamp or booster transformer even with a high performance MC type cartridge.

PHONO EQUALIZER

Rotel's RA 2030 use a 2-stage DC connected differential input circuit with low noise FET. With a push-pull output stage, this results in excellent S/N high overload capacity and accurate input impedance.

OPTIMUM PHONO IMPEDANCE AND LOAD CAPACITANCE SWITCH (FOR MM CARTRIDGES)

2 switches are attached tothe above Rotel models which make it possible to create the optimum load conditions for MM (moving magnet) cartridges. These permit choise of three impedance loads (35 kohms, 50 kohms, and 70 kohms) and 3 additional capacitance positions (0, 100, 200 pF) onthe Phono1.

2-WAY TAPE DUBBING

Since the tape monitor switch and the recording selector function independent of each other, dubbing between 2 tape decks is possible irregardless of what is being played through the amplifier. Simple operation of the switch permits dubbing between 2 tape recorders in either direction.

TONE CONTROL

Use of a DC amp style tone control that eliminates coupling capacitors from the NF loop guarantees accurate reproduction even at low frequencies. Because of this circuitry design placing the Tone Defeat switch "ON" allows operation as a totally flat buffer amp. Control range is -10 dB +10 dB.

SUBSONIC AND SUPERSONIC FILTERS

Rotel 2000 series comes equipped with two filters - subsonic and supersonic - that eliminate unwanted components from the very high or very low frequency ranges inaudible to the human ear can have a negative effect on the audible range due to intermodulation and excessive base speaker cone excursions. The Rotel filters eliminate these at 12 dB/oct slope to provide perfect reproduction of the original sound.

Power amplifier part

Output power (both channel drive):

100 W/ch (4 Ω, 1 kHz)

80 W/ch (8 Ω, 20 Hz - 20 kHz)

THD: 0.01% (at the time of an output power 20 Hz - 20 kHz)

Cross modulation distortion: 0.015% (at the time of an output power 8Ω)

Frequency characteristic (1 W/ch; 8 Ω): 2 Hz - 200 kHz; +0 -3 dB

Input sensitivity/impedance: 1V/50kΩ

Dumping factor: 90 (1 kHz)

S/N ratio (IHF-A network short-circuit): 105 dB

Crosstalk (10 kHz): 60 dB

Equalizer part

THD:

Phono MAG : 0.005%

Phono MC : 0.006%

RIAA deflection (20 Hz - 20 kHz): ±0.3 dB

Input sensitivity/impedance:

Phono1 MAG : 2 mV/35, 50, 70 kΩ/0, 100 or 200 pF

Phono2 MAG : 2 mV/50 kΩ

Phono3 MC : 200 mV/150 Ω

Maximum permissible input (1 kHz, THD 0.5%):

Phono MAG : 300 mV

Phono MC : 10 mV

Preamplifier part

THD: 0.008% (at the time of an output power 20 Hz - 20 kHz)

Frequency characteristic: 4 Hz - 160 kHz

S/N ratio (IHF-A network):

Tuner, Aux : 95 dB

Tape monitor : 95 dB

Remains noise (at the time of a volume min): 6 mV; 100 dB

Input sensitivity/impedance:

Tuner, Aux : 150 mV/ 50 kΩ

Tape monitor : 150 mV/50 kΩ

Maximum permissible input (1 kHz, THD 0.5%): 15 V

Slew rate: 30 V/muS

Square wave rise time: 3 microS

Subsonic Filter: 15 Hz, 12dB/oct

Supersonic filter: 24 kHz, 12 dB/oct

Control width:

Bass: ±10 dB (100 Hz)

Treble: ±10 dB (10 kHz)

Max. power consumption: 500 W

Dimensions (W x H x D): 482 x 143 x 408 mm

Weight: 18 kg

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