Commentary

A control amplifier developed as a successor to the C-200 series.

The line amplifier uses a balanced transmission method.
The line-input amplifier consists of an input-differential complimentary service push-pull + cascode push-pull circuit. The input-stage FET circuit is also cascode + constant current load. High-gm elements are used for the FET.
If both + (non-inverting) and - (inverting) inputs are input, the amplifier becomes a balanced input amplifier. If the inverting input is input to ground, and if the inverting input is input to non-inverting, it becomes a non-inverting unbalanced amplifier.
In addition, it is a direct-coupled amplifier configuration with DC servo.

It uses a newly developed 4-linked volume controller.
In particular, a mirror-finished resistor with a low distortion factor is adopted. The mirror-finished resistor has good distortion characteristics and excellent wear resistance. In addition, there is no grease or anything that impairs sound quality between the brush and the resistor.
In addition, unlike the general volume structure, the resistor rotates and the brush part is fixed and directly exposed as a terminal. This reduces the number of metal joints from five to three and improves the sound quality.
Both - (inverted) and + (non-inverted) of the input balance circuit are equipped with these attenuators, and a four channel structure is used to link the left and right channels.

The power supply consists of an equalizer amplifier, a line amplifier, and a presence control amplifier, all of which are independent of each other. In addition, a dedicated power transformer is provided for each of the left and right channels to ensure complete electrical separation.
Mechanically, each amplifier is a unit amplifier with independent left and right channels to prevent interference between left and right and each unit.

Equipped with a newly developed direct connection headphone amplifier.

Equipped with 4-point 6-frequency presence control.
We take care to adjust the four points that are most effective in expressing music, and there are six types of 4-point stores with variable frequency.
The mid-range has center frequencies of 500 Hz and 2 kHz, 500 Hz controls the expression of rhythm instruments, 2 kHz controls vocals and so on, and Q = 0.707, which determines the sharpness of peaks, is selected based on audition results from a wide range of program sources and provides natural variation.
Two types of bass and treble can be selected to adjust the overall energy balance and atmosphere.
The presence control configuration consists of a combination of additive filters with little degradation in sound quality. By using carefully selected elements with an emphasis on sound quality, deterioration in characteristics and sound quality is prevented. In addition, when the presence control is off, consideration is given to being out of the signal path.

The equalizer amplifier section is equipped with a dedicated input circuit that matches the MM and MC cartridges.
For MM input, it is composed of FET elements with high S/N matching to the high output impedance of the cartridge. For MC input, it is composed of a differential input circuit with low-noise elements to receive small signals with low impedance. By reducing the impedance of the NFB loop, low-noise reproduction is possible.
The gain is 60 dB for MC, 30 dB for MM, or 36 dB for MM depending on the output of the cartridge.

The audio switching part uses a logic relay control circuit that uses a relay for the communication industry that uses nitrogen gas filled and gold bonded contacts to prevent signal degradation due to excess wiring.

The recording output for the balance input is equipped with a special balance / unbalance conversion amplifier, so that the balance input can handle the tape like any other unbalanced input.

Equipped with a Loudness Compensator switch that adjusts the sound perception and energy balance during low volume playback.
100 Hz : + 6 dB when the volume adjustment position is -30dB, and + 4 dB when the volume adjustment position is -20dB. The degree of correction is automatically adjusted according to the volume adjustment position.

Equipped with an attenuator switch that can attenuate up to -20dB with one touch.

Equipped with a subsonic filter.

The top bonnet is made of thick aluminum hairline finish, the front panel is made of aluminum with gold-style scratch hairlines, and both sides have natural Persimmon finish boards.

Model Rating

Type	Stereo Preamplifier
Frequency Response	balanced input (CD, Line) : 1.0 Hz to 600 kHz + 0 -3.0 dB 20 Hz ~ 20 kHz + 0 -0.2 dB CD, Tuner, Line, Tape Play : 1.0 Hz to 600 kHz + 0 -3.0 dB 20 Hz ~ 20 kHz + 0 -0.2 dB AD input : 20 Hz to 20 kHz ± 0.2 dB
Total Harmonic Distortion Factor	0.005% (at all input terminals)
Input sensitivity / impedance (at rated output / 0.5 V output)	AD MM1 : 8.0mV/2.0mV/47k Ω AD MM2 : 4.0mV/1.0mV/47k Ω AD MC : 0.25mV/0.063mV/100 Ω Balanced : 252mV/63mV/40k Ω Unbalanced : 252mV/63mV/20k Ω
Rated Output / Impedance	Balanced output : 2.0V/50 ohm Unbalanced output : 2.0V/1 ohm Tape rec : 252mV/200 Ω
Headphone jack	Applicable Impedance : 4 Ω ~ 600 Ω
S/N / Input conversion noise	Input Short IFF-A Correction Input Terminal Rated Input S/N Input Conversion Noise EIA S/N AD MM1: 96dB -138dBV 85dB AD MM2: 92dB -140dBV 86dB AD MC: 80dB -152dBV 83dB Balanced: 112dB -124dBV 94dB Unbalanced: 116dB -128dBV 96dB
Maximum power level (0.005% distortion rate, 20 Hz to 20 kHz)	Balanced output:7.0V Unbalanced output:7.0V Tape rec:7.0V
AD Maximum Input Voltage (1 kHz, 0.005% distortion)	MM1:250mV MM2:125mV MC:8mV
Minimum Load Impedance	Balanced output : 600 ohms Unbalanced output : 1k Ω Tape rec : 10k Ω
Gain	Balanced input → Balanced output : 18 dB Balanced input → Unbalanced output : 18 dB Balanced input → rec output : 0 dB Unbalanced input → Balanced output : 18 dB Unbalanced input → Unbalanced output : 18 dB Unbalanced input → rec output : 0 dB AD MM (1/2) input → Balanced output : 48/54dB AD MM (1/2) input → Unbalanced output : 48/54dB AD MM (1/2) input → rec output : 30/36dB AD MC input → Balanced output : 78 dB AD MC input → Unbalanced output : 78 dB AD MC input → rec output : 60 dB
Presence Control	4-band Frequency : 40Hz/100Hz switching, 500 hz, 2 khz, 8kHz/20kHz switching Variable range : + / - 10 dB
Loudness Compensator	+ 6 dB (100 Hz, Volume -30dB)
Subsonic Filter	17 Hz, -12dB/oct
Attenuator	-20dB
Semiconductors used	Transistors : 59 FET : 25 IC : 26 pcs Diodes : 57
Power Supply Voltage	100 VAC / 117 V / 220 V / 240 V, 50Hz/60Hz
Power Consumption	19W
External Dimensions	Width 475x Height 149 (including legs) x Depth 375 mm
Weight	18.4kg