Ravensbrook Stereo Amplifier

Following the success of the Ravensbourne stereo amplifier, the manufacturers now announce a new model, called the Ravensbrook, with a more modest output of a nominal 10 watts per channel. It is claimed that a number of original ideas have been developed to improve performance and reduce cost at the same time. The single printed circuit board is made of fibreglass, and this method is thought to be exclusive to Roger’s amplifiers.

The four-way push-button Input selector provides for selection of Disc, Tuner, and Tape Inputs; the fourth button gives Mono/ Stereo operation. When reproducing Mono the left-hand input channel is connected to both speakers and the output from a compatible stereo pickup is connected in parallel for playing mono records. The provision of a Tape panel socket (duplicated at the rear) to the DIN Record/Playback standard together with full monitoring via a three-head machine make this model particularly interesting to recording enthusiasts. On the disc side a dual sensitivity switch for virtually all high-quality pick-ups, from ceramic to the new very low output magnetic types.

Power output is quoted as 10 watts RMS into 15 ohms (15 watts RMS into 8 ohms) and total harmonic distortion as less than 0.1% 1kHz at 10 watts into 15 ohms and less than 0.25% at 10 watts into 15 ohms over the range 100 Hz to 10 kHz.
Output impedance matching is 8 to 16 ohms.

 Special features of the circuitry include a low-noise pick-up input stage using a special low-noise PNP transistor in conjunction with a high-output second stage to achieve a wide dynamic range and avoid distortion on peak recorded passages. Quadrifilar transformers are used to drive two pairs of high current gain transformers giving very low distortion. All four windings on the transformers are wound simultaneously, a technique which is said to result in maximum coupling and perfectly balanced windings.

Dimensions arc 14⅛ x 9 ⅞ x 5 inches including knobs and feet, and prices are £42 10s. for the chassis model, £47 10s. for the cased model, and the teak case alone if required £5 plus 10s. 1d. purchase tax.

Sockets :

• Disc Input      3 pin DIN
• Tuner Input    3 pin DIN
• Tape (on back)  5 pin DIN
• Tape (on front)  5 pin DIN
• Speaker outputs 2 pin DIN x2

This amplifier was superseded by the Ravensbrook Series 2 model with a headphone socket.

The transistors listed are one channel only plus the voltage regulator (2N3611).

In questo link sono elencati 46 modelli, di cui 45 con immagini e 6 con schemi.
Elenco delle radio e altri apparecchi della Rogers, Catford (see also Rogers Birmingham)