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





Yamaha CR-840

 When speaking of the OTS (Optimum Tuning System), an easy-to-use Yamaha feature that automatically locks in the exact center of the tuned channel - for the lowest possible distortion.
"the muting and OST systems operated flawlessly" Stereo Review said, and more "The harmonic distortion of the CR-840 was so low that without the most advanced test instruments it would have been impossible to measure it."
 Among Yamaha's most significant features is the continuously variable loudness control. By using this control, the frequency balance and volume are adjusted simultaneously to compensate for the ear's insensitivity to high and low frequency sound at low volume settings. Thus, you can retain a natural-sounding balance regardless of listening level.
 And there' more. Like the Rec Out/Input Select feature. These separate controls allow you to record from one program source while listeningto another program source. All without disturbing the recording process, Stereo Review's comment was, … the tape recording functions of the CR-840 are virtually independent of its receiving functions." one could not ask for greater flexibility.
 In summing up their reaction to the CR-840, Stereo review said, "Suffice it to say that Yamaha make it possible for a moderate-price receiver to provide performance that would have been unimaginable only a short time ago." And the CR-840 is only one example in Yamaha's fine line of receivers.
 

Specifications
Audio Section
Minimum RMS Output Power per Channel:
65 Watts at 4 Ω from 20 - 20,000 Hz (at no more that 0,02% THD)
60 Watts at 8 Ω from 20 - 20,000 Hz (at no more than 0,02% THD)
Continuous RMS Power (both channels driven, 1 kHz):
75 Watts at 4 Ω
65 Watts at 8 Ω
Signal-to-Noise ratio (IHF A Network)
Phono :  94 dB (Input shorted)
Aux, Tape 1 and 2 :  100 dB
Residual Noise : 0,17 mV
Distortion 20 Hz to 20 kHz:
Phono to Rec Out :  0,02% 1V output
Aux, Tape to Sp Out ( 8 Ω) :  0,01% at 30 W
Noise-Distortion Clearance Range (NDCR) for 0,1% into 8 Ω at 1 kHz:
From 10 mW to 60 Watts with Vol -20 dB (Phono Input to SP out)
Power Bandwidth (IHF):  10 Hz to 40 kHz
Damping Factor (at 1 kHz):  better than 40 into 8 Ω
Iunput Sensitivity / Impedance:
Phono :  2,5 mV / 47 k Ω
Aux, Tape 1 and 2 :  120 mV / 40 k Ω
Maximum Input levels:
Phono :  140 mV at 1 khz
Output level / Impedance:
Rec Out terminals Phono :  120 mV / 220 Ω (rated)
Aux , tape :  120 mV / 5 k Ω
Frequency Response:
Phono RIAA deviation :  0,4 dB
Aux, tape 1 and 2 to Sp Out :  20 Hz to 20 kHz, ±0,3 dB
Tone Control Characteristics
Bass Turnover Frequency :  350 Hz
Bass Boost/Cut :  ±10 dB at 50 Hz
Presence Center Frequency :  3 kHz
Presence Boost/Cut :  ±6 dB
Treble Turnover Frequency :  3,5 kHz
Treble Boost/Cut :  ±10 dB at 20 kHz
Filters and Loudness Control Characteristics:
Low : 25 Hz (12 dB/octave)
High :  8 kHz (6 dB/octave)
Loudness Control :  Level-related equalization
FM Tuner Section
Tuning Range:  87,6 to 108 MHz
Usable Sensitivity [300 Ω/75 Ω]:  9,3 dBf (1,6 µV) / 9,3 dBf (0,8 µV)
50 dB Quieting Sensitivity :
Mono : 15,3 dBf (3,2 µV)
Stereo :  37,3 dBf (40 µV)
Image Response ratio (98 MHz):  80 dB
IF Response Ratio (98 MHz):  100 dB
Spurious Response Ratio (98 MHz):  100 dB
AM Suppression Ratio (IHF):  60 dB
Captur Ratio:  1,5 dB
Alternate Channel Selectivity:
Locl : 48 dB (IHF)
DX :  82 dB (IHF)
Signal-To-Noise Ratio IHF (at 65 dBf):
Mono :  84 dB
Stereo :  80 dB
Distortion (at 65 dB)
Mono
100 Hz :  0,1%
1 kHz :  0,08%
6 kHz :  0,15%
Stereo
100 Hz :  0,1%
1 kHz :  0,1%
6 kHz :  0,2%
Intermodulation Distortion (IHF) [Mono/Stereo]:  0,08% / 0,08%
Sub-Carrier product Ratio:  609 dB
Stereo Separation
50 Hz :  45 dB
1 kHz :  50 dB
10 kHz :  45 dB
Blend :  10 dB
Frequency Response
50 Hz to 10 kHz ,  ±0,4 dB
30 Hz to 16 kHz , +0,4 -1,0 dB
Muting Threshold:  19,2 dBf (5 µV)
Auto DX Sensitivity:  36,1 dBf (35 µV) or at 50 dB /N
AM Tuener Section
Tuning range:  525 to 1605 kHz
Usable Sensitivity (IHF):  15 µV
Selectivity (1,000 kHz):  30 dB
Signal-to-Noise Ratio:  50 dB (at 80 dB/m)
Image response Ratio (1,000 kHz):  40 dB
IF response Ratio (1,000 kHz):  35 dB
Spurious Response Ratio (1,000 kHz):  60 dB
Total Harmonic Distortion:  0,4%
Tuner Section Output level/Impedance
FM (100% mod. At Rec Out) :  450 mV /3,9 k Ω
AM (30% mod. At Rec Out) :  150 mV / 3,9 k Ω
General
Semiconductors:
47 Transistors;  9 ICs; 1 FeT; 14 Diodes, 3 Zener Diodes; 7 LEDs; 5 Ceramic Filters
Power Supplies:  AC 120 V, 220 V  50/60 Hz
Power Consumption:  340 W at 120 V
Dimensions (W x H x D):  510 x 167 x 386 mm (20" x 6-9/16" x 15-1/4")

Weight:  13,6 kg (30 lbs)

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