Audio Database

The

Pioneer C-21
60,000yen(around the 1980 time)

Description
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The preamplifier of a simple stream composition of having been devoted to the single functionality, in order to pursue a tone quality on the contrary at the origin of a preamplifier and to realize a tone quality with a high purity.

Two steps of differentials and current mirror circuitry Class-A SEPP are used for the circuit system of an equalizer amplifier.
Many properties are improved by this circuitry that made importance the improvement in a distorted reduction and an SN ratio.
Furthermore, }0.5% of a resistance-value error and the precision small metals skin membrane resistance of }100 ppm/degree C of temperature characteristics are used for an equalizer element. Moreover, elements selected carefully, such as a polypropylene capacitor of }1% of a capacity error, are used.
Moreover, the high voltage of }37V was impressed to this circuitry, and the generous dynamic margin of 300mV of maximum permissible inputs is secured in it to the sensitivity of 2.5mV.

Since the performance of various cartridges is demonstrated, it can be independent respectively, six sorts of load resistance and six sorts of load capacity can be chosen, and a total of 36 sorts of cartridge loadings can be set up.
Moreover, the position of 100 ohms of load resistance is suitable for connecting MC cartridge with a large Output voltage direct.

The flat amplifier part as well as an equalizer part has adopted the 2 steps of differentials amplification.
The using and interval of an element which had adopted the current mirror circuitry as the middle amplification stage, and were selected carefully while using the low-noise transistor for the first rank are +0 the frequency characteristic of 10Hz - 100kHz. -0.2 dB, 0.005% of the distortion, and the property of an SN ratio of 100dB are secured.

The power-source part constituted the constant-voltage regulated power supply from a L/R independent coil transformer large-sized as a preamplifier, and has eliminated the cross interferencee between channels.
Moreover, the quality of stereophonic reproduction, such as also using the reed relay of a muting circuit by two L/R independencies, and also considering it as the special design incorporating the spacer which suppresses the interference between channels also to a function switch, is thought as important.

The volume has adopted the attenuator type of 32 steps by which the silver print of the contact was carried out.

The gain control by 22 contact attenuator which achieved the L-R independency is carried in the flat amplifier output stage.
The silver palladium treatment of the contact is carried out.

Rear

Rating of a mode
Form Stereo preamplifier
Circuit system Equalizer-amplifier part: 2 steps of differentials current mirror amplification Class-A SEPP
Control amplifier part: 2 steps of differentials current mirror amplification Class-A SEPP
Input terminal Phono: 2.5mV/100 ohm, 10kohm, 25kohm, 50kohm, 75kohm, 100kohm
Cartridge load capacity: 100pF, 150pF, 200pF, 300pF, 400pF, 500pF
AUX1, 2, Tape Play:150mV /, 50kohm
Phono maximum permissible input 300mV (1kHz, THD 0.01%)
Output-terminal Tape Rec: 150mV / 1kohm
Output(RL:50kohm): 1V/450 ohm (rate), 20V/150 ohm (MAX)
THD (20Hz - 20kHz) Phono: 0.006% (at the time of 1V output Volume-20 dB, gain-control 0dB)
AUX: 0.005% (at the time of 1V output gain-control 0dB)
Frequency characteristic
Phono: 20Hz-20kHz}0.2dB
AUX: 10Hz-100kHz+0 -0.2 dB
3Hz-300kHz+0 -1.0 dB
SN ratio (IHF, A network)
Short circuit
Phono: 80dB (output 1 V:00)
AUX: 100dB (output 1 V:00)
Phono Subsonic Filter 15Hz, 6dB / oct
The semiconductor used Transistor: 36 pieces
Diode, other:47 piece
Supply voltage 100V, 50Hz/60Hz
Power consumption
(Electrical Appliance and Material Control Law)
10W
AC outlet Power-switch interlock: Three lines
Power-switch un-interlocking.: Two lines
Dimensions Width 420x height 81x depth of 357mm
Weight 6.3kg