Audio Database

The

ROTEL RB-2000
110,000yen( at the 1970 in-the-late time(?))

Description
 
DC power amplifier of AB class operation.

Circuitry has a 3 steps of first rank dual FET differential-amplifications cascade bootstrap pure complimentary push pull + Darlington connection, a whole page hardwired-connection OCL scheme, and DC amplifier composition.
The low-noise type thing which excelled Dual FET in the property thermally and electrically is selected carefully, and the pair property required for the element of DC amplifier first rank is maintained.

The whole page DC stream composition is adopted and the capacitor is banished from the signal system or NF loop.
About the drift of the middle point potential which poses a problem, it has realized stabilizing DC balance with a circuitry technology at the same time it raises the stability of the middle point potential of a differential-amplification part.

Taking advantage of the merit of the tone quality of Class-A amplifier, AB class operation method which can acquire the Oide power is adopted.
Usually, it is a Class-A operation at the time, and it changes to B class operation automatically at the time of the Taishin number which needs big power.

The low distortion is realized by investigating thoroughly until it results in the design of the printed circuit board, or a placement of a shielding code including a material or component partses.

It excelled in the high efficiency at the regulation, and the large-sized toroidalcore type transformer with little leakage flux is adopted as a power-source part.

As a protection network, the electro carry control ASO (area of safe operation) circuitry and DC feedback power limit circuitry are carried. The electro carry control ASO circuitry has protected the transistor and speaker of amplifier by relay operation. Moreover, the DC feedback power limit circuitry operated quickly to the overload, and has protected the transistor.
Furthermore, in returns-to-biases-2000, a relay for exclusive use and an in rushes absorber are prepared also to the in rushes electric current at the time of the power activation which poses a problem with the Oide power amplifier, and the security and the robustness are improved.

The peek power meter is carried. Unlike the usual meter, this meter serves as a type which displays peek power with a quick elevation of a pointer and late return. Thereby, reading of the peek of power is made easy.
Moreover, a tick mark is logarithmic compression mold and enables the exact window from the very small output time till the Oide power.

Though DC component is cut with DC direct interconnection, two input terminals with an input capacitor termination which can maintain a tone quality and a property are carried.

The termination by which the gilding treatment was carried out is adopted.

The front panel serves as EIJ specification rack-mounted type.


Rating of a mode
Form Stereo power amplifier
Output power (both channel drive) 140 W/ch (4 ohm, 1kHz)
120 W/ch (8 ohm, 20Hz - 20kHz)
THD 0.01% (at the time of 20Hz - 20kHz, and an Output power)
Cross modulation distortion 0.015% (at the time of an Output power 8ohms)
Frequency characteristic (1 W/ch, 8ohm) DC in:DC-100kHz+0 -1dB
AC in: 5Hz-100kHz+0 -1dB
Input sensitivity/impedance 1.5V/50kohm
Dumping factor (8ohm) 60 (20Hz - 20kHz)
100(1kHz)
S/N ratio (IHF-A network short-circuit) 110dB
Crosstalk (10kHz) 65dB
Slew rate 40V/muS
Square wave rise time 2microS
Maximum electric power consumption 900W
Dimensions Width 482x height 143x depth of 430mm
Weight 18kg