Revox B780 receiver

In its B780 receiver Revox has achieved a truly symbiotic relationship between tuner and amplifier. Each retains its identity; the circuitry and performance of both the B760 Digital Frequency Syntesizer FM Tuner and the Revox B750 Integrated Amplifier are combined in the B780. instaed of trading flexibility for single-unit convenience, however, the capabilities of each unit have been enhanced by their merger into the Revox B780.

What makes the B780 more than the sum of its component parts is a microprocessor unit that takes over switching functions that would normally require an inordinate number of hard-wired connections and printed circuits. At the same time that it serves to increase the reliability of the B780, the microprocessor control system makes the receiver even easier to use.

As the nerve center for your entire component high-fidelity system, the Revox B780 provides connection and control facilities for two loudspeaker systems and for fourstereo sources in addition to its built-in FM tuner; a phono cartridge, two tape recorders, and an auxiliary source, such as a Tv set, AM tuner, or the like. Each input is fully buffered, and so, can be used independently. That is to say, if you wish, you can record an FM broadcast on your open real deck at the same time as you are listening to the playback of an LP. in place of the usual rotary "Selector Switch", your choice of input signals is electronically routed through the amplifier via individual pushbuttons ( with lighted indicators) that command the microprocessor to switch to the appropriate source. Even when the B780 is turned off, the microprocessor retains the last-selected program source in its memory, so when you turn the unit on again. It "wakes up" properly switched to that input.

Lighted digits show which program source is going to the recorder circuits. These pushbutton choices are also retained in the microprocessor memory, giving you the convenience of mechanical switching with vastly improved reliability.

The same principle of all pushbutton operation is applied throughout the tuner section of the B780. there is no conventional FM dial for the selected station frequency, as it is indicated ( to two decimal places ) on a digital red-out. There is no conventional FM dial for selected station frequency, as it is indicated on a digital read-out. There is no conventional tuning knob, with its dial cord and pulleys; rather; pushbuttons cause the tuner to scan upward or down-ward in frequency in 50 kHz incrementes, stopping at each receivable station, or at each stereo station, or switching into mono when the station's signal strength is not adequate for proper stereo reception.

Because of its quartz-crystal controlled frequency synthesizer, tuning is always exact; only by using a laboratory FM generator and distortion analyzer could such precision be obtained with normal manual tuning. And the pushbutton memory system of the B780 allows you to store the frequencies of up to 18 favorite stations for instant recall.

Long awaited, the Revox B780 receiver embodies the most up-to-date technology, in its most convenient form, in the service of the one goal that inspire all Studer Revox products; to bring you the most faithful possible reproduction of musical sound.

 Specifications:

Tuner Section

Tuning Range:  87,50 - 107,975 MHz

Tuning Accuracy:  ±0,0025%

IHF (30-dB) Monophonic Usable Sensitivity:  19,µV / 300 Ω (10,8 dBf)

IHF (IHF-T-200) Monophonic 50 dB Quieting Sensitivity:  2,5 µV / 300 Ω (13,2 dBf)

IHF (IHF-T-200) Stereophonic 50 dB Quieting Sensitivity:  30 µV / 300 Ω (34,8 dBf)

Image Rejection:  106 dB

IF Rejection:  110 dB

Spurious Response Ratio:  106 dB

Capture Ratio (at 65 dBf):  2 dB

Selectivity Adjacent Channel:  16 dB

Selectivity Alternate Channel:  78 dB

 AM Suppression:  70 dB

Subcarrier Product Rejection:  72 dB

Frequency Response:  30 Hz - 15 kHz ±1 dB

Deemphasis:  50 or 75 µs (switchable) with built-in Noise Reduction Unit 25 µs

Total Harmonic Distortion(at 65 dBf):

At 100 Hz :  0,15% (mono);  0,35% (stereo0

At 1 kHz :  0,1 (mono);  0,25% (stereo)

At 6 kHz :  0,2% (mono);  0,2% 9stereo0

Stereo Separation [Mono]:

At 100 Hz :  40 dB

At 1 kHz :  42 dB

At 10 kHz :  33 dB

Signal-to-Noise ratio 9at 65 dBf):

Mono :  78 dB

Stereo :  74 dB

Muting Thresholds:

Mono :  17,3 - 37,3 dBf

Stereo :  25,2 - 65,2 dBf

Antenna Inputs:

60 -75 Ω coaxial

240 - 300 Ω balanced

Audio Outputs:

75 kHz deviation/400 Hz equals 0,7 volt at the output Tape 1

15 kHz deviation/400 Hz produces 70 watts/ 8 Ω at the output Speakers A/B

Oscilloscope Output:

Vertical :  50 mV /75 Ω, RF =1 Volt

Horizontal :  75 kHz deviation = 2,8 Volt pp

Amplifier Section

Power Output:  70 watts/channel min. RMS into 8 Ω from 20 Hz - 20 kHz with no more than 0,05% T.H.D.

Total Harmonic Distortion:   0,03% at rated output

IHF Intermodulation Distortion (14 kHz/15 kHz):  less than 0,03% at rated output

TIM Distortion (Otala, lowpass 10 kHz):  less than 0,08% at rated output

Dynamic Headroom:  1 dB

Slew rate:

15 V/µs ( limited by internal low pass filter)

30 V/µs (without low pass filter0

Frequency Response:  20 Hz - 20 kHz +0 dB/-0,7 dB

Damping Factor:  better than 100 at 8 Ω and 1 kHz

Inputs Sensitivity (for 70 watts [8 Ω])/Impedance

Aux, Tape 1, 2 :  150 mV/50 k Ω

Phono :  3 mV/47 k Ω, 220 pF

PWR In :  1 V/50 k Ω

Input Overload Margin (phono, Aux, Tape 1, 2):  better than 30 dB

Outputs;

DIN Connector Tape 2/Out:  5,5 mV/R 10 Ω

Speakers A, B :  23,7 V (8 Ω)

Tape 1 :  135 mV/R min. 47 k Ω

Pre Out (DIN connector) ;  0,85 V/R min. 10 k Ω

Pre Amp Out (jack) :  0,85 V/R min. 47 k Ω

Phones :  11,8 V/R 220 Ω

Signal-to-Noise Ratio (RMS value, unweighted 20 Hz - 20 kHz relative to 70 W/8 Ω)

Aux, Tape 1, 2 :  better than 90 dB

Phono 1 + 2 9ref. 5 mV, A-weighted):  better than 82 dB

Crosstalk (at 1 kHz):  better than 70 dB

Phono Equalization:  20 Hz - 20 kHz ±0,5 dB (in accordance with IEC 98, MOD 4 1976, consistent with RIAA)

Tone Controls:

Bass  :  ±8 dB at 120 Hz

Treble :  ±8 dB at 8 kHz

Presence ;   ±8 dB at 3 kHz

Filters:

Low :  50 Hz, -3 dB (12 dB/oct)

High :  8 kh, -3 dB (12 dB/oct)

Loudness (Vol-40 dB):  100 Hz +5 dB , 10 kHz +6 dB

General Section

Semiconductors:  122 Transistors;  99 Diodes;  19 variable capacity Double Diodes:  46 ICs:  1 micro-processor; 4 K x 8 Bit, 5 Bridge Rectifiers, 9 7-Segment Displays

Electric Current Supply:  100, 120, 140, 200, 220, 240 V AC ±10% (voltage selector) 50/60 Hz

Power Consumption:  550 W max.

Dimensions (W x H x D):  452 x 151 x 420 mm (17,8" x 6" x 16,5 ")

Weight:  17 kg (37 lbs)