STATUS - SOLD
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Description :
The Rogers Ravensbourne is a 25 Watts Integrated Stereo Amplifier/Control Unit, employing Silicon Transistors throughout, designed for use in Home Stereo Systems where the highest possible standards of performance are required. In a single, compact, superbly styled unit the Ravensbourne provides a carefully chosen specification, evolved from a comprehensive study of user requirements. Input facilities cater for all high quality programme sources while control facilities combine simplicity with sufficient flexibility to ensure that optimum results can be obtained from a wide range of programme material under all conditions.
The main amplifier is carried on a translucent glass-fibre printed circuit board and consists of a voltage amplifier stage directly coupled to a split load phase-splitter stage with DC stabilisation by local feedback. The phase splitter is RC coupled to a pair of NPN silicon transistors operating in Class A push-pull as emitter followers. Their output feeds the centre-tapped primary winding of an interstage transformer. Two secondary windings feed a pair of high current-gain output silicon transistors. The design of this double push-pull transformer is of interest. Using special grain-orientated laminations, the four separate windings are simultaneously wound thus ensuring maximum coupling and perfect electrical balance. It also gives a very low leakage inductance which ensures high stability even without negative feedback. The output transistors, Solitron SDT9271 type, have a cut-off frequency of 4 MHz and thus permit negative feedback over the main amplifier of 36 dB.
Remarkable technical performance figures on the Rogers Ravensbourne have been achieved. The figures are so good that the amplifier is audibly better than any comparable amplifier. There are three main facets of performance account for this superiority; exceptionally low levels of intermodulation and harmonic distortion, virtually perfect transient response and excellent signal to noise figures. By comparing figure for figure, the complete technical specification of the Ravensbourne with that of any of its contemporaries and it will be found superior in virtually every respect. By allying this exceptional technical performance with superb new styling, meticulous construction and wiring, high quality materials and a comprehensive overall specifiaction and the user will have an amplifier destined to become the leader in it's field.
Specifications :
Power output.....................................25 + 25 Watts RMS into 15 or 18 ohms
.....................................13 + 13 Watts RMS into 4 ohms, 25 to 25kHz.
Harmonic distortion............................Better than 0.06%, up to 15 Watts into 15 ohms at 1kHz
............................(0.1% average at 25 Watts)
IM Distortion......................................Better than 0.25% up to 15 Watts into 15 ohms at 1kHz
......................................(0.5% average at 25 Watts)
NFB..................................................36dB at 15 ohms, Stability margin 16 dB.
...................................................Resistive or Loudspeaker load.
Signal to Noise Ratio..........................V.C. minimum better than -80dB.
...........................V.C. maximum, open or short circuit input.
...........................Radio, Auxiliary and Tape input, better than -75dB
...........................Disc input, short circuit or 10k load,
...........................4 & 8 m/V, better than -60dB, 100 and 200m/V,
...........................better than -65dB, all relative to 25 Watts.
Crosstalk...........................................Radio, Auxiliary and Tape,
............................................better than 45dB, 25Hz to 1kHz, better than 30dB at 10kHz.
............................................Disc, short circuit or 10K load, better than 40dB, 25Hz
Input Sensitivity..................................Disc 4/8/100/200 m/V, for 25 Watts.
..................................Impedance 50K. Response +/- 0.5dB RIAA.
...................................Dynamic Range 26dB, 30Hz to 10kHz.
...................................Auxiliary, Radio & Tape Relay, 200m/V for 25watts. Impedance 100K.
...................................Response Flat +/- 1dB 25Hz to 25kHz.
...................................Dynamic Range Infinite.
Tape Record Output............................200 m/V for rated input sensitivities.
.............................Minimum external source impedance 100K
Bass Control......................................+/- 14dB, 40Hz
Treble Control.....................................+/- 14dB, 10kHz
Balance..............................................9dB range
Low pass filter.....................................6kHz or 9kHz, 20dB per octave
High pass filter....................................20Hz, 30dB per octave
Operating Voltages..............................110/125/220/240 V, 50/60Hz
Mains Consumption.............................Quiescent 40 Watts, 25 Watts output to both channels 15 ohms,
..............................110 Watts.
Dimensions(w x d x h)..........................38 x 29.5 x 15 cm
Weight................................................9kg
Miscellaneous :
Made in..............................................UK, England
Condition............................................7/10
Reviews :
http://www.gramophone.net/Issue/Page/June%201968/110/802817/Rogers+Ravensbourne |
