The Ultimate in
Control and Performance
The
Yamaha C-70 Stereo Control Amplifier reflects an immense amount of research and
development, vast technological resources and years of accumulated experience
in Natural Sound amplifier design. The remarkable C-70 features a new Extended
Rolloff Equalizer that eliminates much of the high-frequency phase deviation of
conventional phono equalizer designs, a New Linear Transfer circuit that
minimizes current distortion caused by semiconductor non-linearity in class-A
amplification stages, completely independent preamplifier stages for moving
magnet and moving coil cartridges ensuring the best possible performance with
each type, a unique Varigain volume control system that completely obviates the
problems associated with conventional attenuator-type volume controls, a full
two-band parametric equalizer for precise response tailoring, and a unoque
inverted output feature that makes it easy to set up a number of
top-performance reproduction systems. In addition to all these advanced
performance and versatility oriented features, the C-70 features the most
exacting, highest-quality design and construction throughout. Careful attention
has been paid to the smallest details, like making sure that the connector
terminals are non-magnetic, in addition to being gold-plated, so magnetic
fields generated by the audio signal in the connector terminals cannot affect
sound quality. In the Yamaha
C-70 you get a sophisticated stereo control amplifier capable of providing the
finest reproduction performance in any sound system - even fully professional
setups.
2-Band Parametric
Equalizer
The
parametric equalizer format is undoubtedly the most comprehensive, precise
means of tonal response tailoring available today. Although it is a fairly recent development in the sound
reproduction field, the parametric equalizer is preferred for response control
in the world's most sophisticated professional recording studios. The reason
for the parametric equalizer's popularity in professional circles is that,
unlike previous equalizer systems, it provides independent, continuously
variable control over frequency, bandwidth and level. That is, you can set any
center frequency for a range of frequencies you need to equalize, you can set
the bandwidth to precisely cover the frequency range to be equalized, and like
conventional equalizer systems, you can precisely set the desired amount of
boost or cut in the frequency range determined by the frequency and bandwidth
controls (Bandwidth is called "Q" in some professional parametric
equalizer systems). The parametric equalizer system provided in the C-70 gives
you the same type of response tailoring flexibility offered by professional
systems. Two bands of equalization are provided: one which covers a frequency
range of fron 31,5 Hz to 800 Hz, and the other with a frequency range of 800 Hz
to 20 kHz. You have continuously variable control over the bandwidth of each
frequancy band (Q = 0,3 - 3), and +/_12 dB boost/cut control in each band. This equalizer system gives you
incredibily broad control over reproduction response, letting you create
precisely the response you need for the most accurate music reproduction in any
listening environment.
Varigain Volume
Control
The
volume controls used in conventional amplifiers are "attenuators".
This means that they perform their volume reduction function by shunting an
appropriate amount of the audio signal to ground. Unfortunately, this type of
volume control has a number of limitations in terms of achieving optimum sound
reproduction quality: 1.Volume reduction generally reduces only the level of
the audio signal, leaving the amplifier's residual noise to obliterate musical
detail when listening at low volume (the Yamaha four-gang volume control used
in the C-50 eliminates this problem). 2.Using a potentiometer to shunt portions
of the audio signal to ground results in mid-circuit impedance variations that
can affect response and distortion characteristics. The Yamaha Varigain volume control system overcomes the above
problems by actually varying the gain of the amplifier to control volume
instead of bleeding off a portion of the music signal. Since the gain of the
amplifier is reduced to lower volume, the amplifier's residual noise is
naturally reduced, while at the same time maintaining the highest possible
signal-to-noise ratio at all volume levels. Further, the Verigain system
produces no impedance variations so distortion and response characteristics are
optimum at aall volume settings. Although this seems to be a relatively obvious
improvement in amplifier design, it took Yamaha ingenuity and attention to
detail to implement the Varigain volume control for your listening pleasure.
New Linera Transfer
Circuit
Although
push-pull class-A-bias amplification stages offer overall reproduction accuracy
greater than classB configurations, conventional versions of this circuit
suffer from current distortion due to the fact that the "gm" (mutual
transconductance) curve of any semiconductor is distinctively non-linear
outside its ideal flattest portion. Signals falling outside the transistors flattest gm range become
distorted. Yamaha engineers
found a way to minimize this type of distortion in the New Linear Transfer
circuit. This advanced circuit adjusts the bias to the size of the input audio
signal, thereby ensuring that the semiconductors linear gm range always
corresponds to the audio signal being processed. This means that an absolute
minimum of current distortion is assured with any input signal. In the C-70,
all amplification stages from the phono equalizer to the output stage feature
the Yamaha New Linear Transfer system.
ERE (Extended
Rolloff Equalizer)
With the vast
improvements in overall amplifier performance, the time has come to provide an
RIAA equalizer capable of equally fine performance. Today's low-level
flat-response amplifiers easily achieve virtually distortion-free response up
to 100 kHz or more. Conventional RIAA equalizer amplifiers, however, come
nowhere near this outstanding performance. The Yamaha Extended Rolloff
Equalizer meets the modern performance standards by eliminating phase variation
beyond the range where conventional equalizers begin to deviate from the RIAA
curve. This type of extended equalizer accuracy was previously impossible to
achieve because of high-frequency instability limitations. The Yamaha ERE
completely eliminates this instability while providing an accurately extended
high-frequency curve, permitting greater reproduction precision than has ever
been possible. The ERE circuit further incorporates a built-in 12 dB/oct
subsonic filter that makes clean, unmuddied reproduction possible down to a low
10 Hz. The Yamaha ERE circuit makes a difference in phono reproduction that you
can hear. And it's a difference you'll really appreciate because you'll
discover nuances and subtleties in the music on your favorite records that you
may never have heard before.
Inverting
Preamplifier Outputs
This highly original
Yamaha feature gives you incredible flexibility in planning and setting up a
true "audiophile class" sound reproduction system. Used in
conjunction with the C-70's standard non-inverting outputs, the inverting
preamplifier outputs let you use two stereo power amplifiers - one for each
channel - to achieve pro-class power output and aound quality; you can couple
the left and right channels to your power amp in invers phase, and reverse the
phasing of your speakers to increase power efficiency and achieve incredibly
natural bass reproduction. You can experiment to find the system that is just
right for ypur listening needs. Whether you end up with one of the advanced
systems described here, or a standard component setup, the C-70 guarantees you
the finest, most "live" music reproduction performance available.
Direct Phono Inputs
For the purest, most
natural disc reproduction performance, the C-70 provides input terminals for
moving magnet and moving coil cartridges that feed directly to their respective
head/EQ amplifiers without being routed through the phono 1 / 2 switch as are
the Phono 1 and 2 inputs. This means that switch contact resistance in this
critical low-level high-gain stage cannot affect disc reproduction quality.
Other
Features:
Selectable MM
cartridge load capacitance.
Rec Out selector. Disc
Direct function.
Solenoid/relay function switching. Dual AUX terminals. Flip-down control cover. Switchable 10 kHz high filter. Switchable 15 Hz subsonic filter. Phono 1/2 selector. Stereo/Mono mode selector. Optional EIA rack mount adaptors.
Specifications
Input
Sensitivity/Impedance:
Phono
MC : 100µV/100 Ω
Phono
MM : 2,5 mV/100 Ω
100 /
220 / 330 pF : 2,5 mV/47 k Ω
Aux,
Tape, Tuner : 150 mV/47 k Ω
Input
Sensitivity (New IHF):
Phono MC :
33µV
Phono MM :
0,83 mV
Aux, Tape,
Tuner : 50 mV
Maximum
Input level (1kHz, 0,01% THD/New IHF)
Phono MC :
13 mV/11 mV
Phono MM :
300 mV/260 mV
Output
Level/Impedance:
Rec
Out : 150 mV/470 Ω
Pre
Out : 1,5 V/47 Ω
Maximum
Output level (20 -20,000 Hz, 0,1% THD)
Pre Out : 10
V
Headphone
Maximum Output level/Impedance (1 kHz,0,01% THD, Output Impedance 68 Ω):
0,48 V
/8 Ω
4,5 V
/100 Ω
Frequency
Response (Aux, Tape, Tuner to Sp
Out): 5 to 100,000 Hz +0 -0,5 dB
RIAA
Deviation:
Phono Mc :
20 to 20,000 Hz ±0,2 dB
Phono MM :
10 to 100,000 Hz ±0,3 dB
Total
Harmonic Distortion:
Phono MC to
Rec Out 3 V output : 0,001%
Phono MM to
Rec Out 3V output : 0,001%
Aux, Tape,
Tuner to pre Out 5V output (Tone switch Off) : 0,001%
Intermodulation
Distortion (Aux, Tape, Tuner 5V output. Tone Switch Off): 0,002%
Signal-to-Noise
ratio (IHF-A Network/New IHF)
Phono MC
(500 V, Input Shorted) : 90 dB / 80 dB
Phono MM
(500 V, Input Shorted) : 94 dB / 82 dB
Aux, Tape,
Tuner (Tone switch Off) : 105 dB / 104 dB
Residual
Noise (IHF-A Network): 1,8µV
Channel
Separation
Phono
MM/Aux, Tape (5,1 k Ω, Input Shorted)
40 Hz, 1
kHz, 10 kHz : 85 dB/100 dB; 80 dB/70
dB; 70 dB/60 dB
Parametric
Equalizer Characteristics
Frequency
Control (Low / High) : 31,5 -800 Hz / 800 Hz - 20 kHz
Level
Control (Low / High): ±12 dB
Bandwidth
Control (Low / High): Q: 0,3 to 3,0
Subsonic
Filter Characteristics: 15 Hz , -12
dB/oct
High Filter
Characteristics: 10 kHz, -12 dB/oct
Audio
Muting: -20 dB
Tone
Control:
Bass
(boost/cut)
Treble
(boost/cut)
Turnover
Frequency:
Bass
Treble
Power
Supply: 110 -120 V, 220 - 240 V AC 50/60
Hz
Power
Consumption: 50 W
Dimensions
(W x H x D): 435 x 96,5 x 369 mm
(17-1/8" x 3.¾" x 14-½")
Weight: 7,2 kg (15 lbs 13 oz)