Commentary

This control center is based on balanced transmission technology and consists of a current feedback amplifier circuit in the line amplifier section. It was developed with an emphasis on quality and high sound reproduction.

The line amplifier section uses a current feedback amplifier circuit that feeds back the output signal in the form of a current.
In this circuit, the impedance of the input terminal on the feedback side is lowered to detect a current, and the current is I-V converted by a transimpedance amplifier to produce an output signal. In this circuit, since the impedance of the feedback input part is very low, phase rotation hardly occurs, and as a result, there is almost no need for phase guarantee.
Therefore, various characteristics can be greatly improved with a small amount of NFB, and dynamic characteristics such as start-up are excellent and natural energy response is realized.

Bridge feedback type balance output circuit is used.
Balanced transmission is a method of simultaneously transmitting positive and negative symmetric signals whose phases are inverted with each other. It has an excellent ability to remove common mode noise components.
The C-265 is equipped with two sets of amplifiers, amp1 and amp2, for balanced transmission. The + - symmetric signal is sent out with low impedance in order to feed back the output of each pair to the other side. The feature of this circuit is that the + - symmetric signal is floated from ground, so even if one side of the output is grounded, both amplifiers operate and the output voltage does not change.

The line amplifier is a pure complimentary service push-pull circuit and consists of discrete parts using a current feedback amplifier circuit. This reduces the phase guarantee of each stage and provides more natural sound quality.
In addition, by placing a balance input amplifier with a gain in front of the volume and placing this line amplifier after the volume, S/N in the practical range with the volume reduced is improved.

The C-265 consists of a balanced input amplifier, a line amplifier, and a balanced output amplifier. These unit amplifiers are fixed with thick aluminum extruding material so that they do not interfere with each other, preventing resonance due to external vibration.

The power transformer and filter condenser are independent on the left and right sides, and the configuration is completely monaural.
This reduces crosstalk between channels through the power supply.
In addition, each unit amplifier is equipped with a dedicated broadband power supply circuit to prevent mutual interference between amplifiers.

A logic relay control method is used to configure the shortest and straight signal path.
The relay used for this is a closed type relay for the communication industry. The contact is gold-plated and crossbar twin system, and low contact resistance and high durability are realized.

There is an amplifier for the headphone to improve the sound quality.
You can also turn off the output to the power amplifier with the output on/off switch, and adjust the headphone output with the main volume.

An additive active filter is used for tone control.
In this method, the original flat signal passes straight through, and characteristics are adjusted by adding or subtracting from the flat signal as needed.

Equipped with 2 balanced inputs.

The volume is a high-quality type using a resistor with a low distortion factor. By combining this volume regulator with a small motor with a clutch, the volume can be controlled by a remote commander.

It is equipped with a slot on the rear panel where an AAB-compliant option board can be added.

Model Rating

(Analog disk characteristics are when the input board AD-10 is added.)
Type	Stereo Control Amp
Frequency Response	Balanced, Unbalanced : 3 Hz to 350 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%
Input Sensitivity / Impedance (Rated Output / 0.5 v Output)	AD MM : 8.9mV/2.2mV/47k Ω AD MC : 0.25mV/0.063mV/10 Ω, 30 Ω, 100 Ω switching Balanced : 252mV/63mV/40k Ω Unbalanced : 252mV/63mV/20k Ω
Rated Output / Impedance	Balanced, Unbalanced output : 2V/50 Ω Tape rec (at AD input) : 252mV/320 Ω
S/N, input conversion noise	Input Short A - Correction S/N at rated output Input Conversion Noise EIA S/N AD MM: 92dB -133dBV 85dB AD MC: 75dB -147dBV 80dB Balanced: 106dB -118dBV 99dB Unbalanced: 105dB -117dBV 99dB
Maximum power level (0.005% distortion rate, 20 Hz to 20 kHz)	Balanced, Unbalanced output : 6.0 v Tape rec:6.0V
Minimum Load Impedance	Balanced, Unbalanced output : 600 ohms Tape rec : 10k Ω
Gain	Balanced, Unbalanced input → Balanced, Unbalanced output : 18 dB AD MM input → Balanced, Unbalanced output : 47 dB AD MC input → Balanced, Unbalanced output : 78 dB
Tone Controls	Bass (300 Hz) + / - 10 dB (50 Hz) Treble (3 kHz) : ± 10 dB (20 kHz)
Loudness Compensator	+ 6 dB (100 Hz, Volume -30dB)
Attenuator	-20dB
Headphone jack	Applicable Impedance : 4 Ω ~ 100 Ω
Power Supply	100 VAC, 50Hz/60Hz
Power Consumption	17W
Maximum External Dimensions	475 mm wide x 150 mm high x 404 mm deep
Weight	15.8kg
Included : Remote Commander RC-20
Remote Control Method	Infrared Pulse Method
Power Supply	DC 3V
Dry Battery	AA type (SUM-3/R6), 2 pcs
Maximum External Dimensions	55 mm wide x 194 mm high x 18 mm deep
Weight	100g (including dry batteries)
Sold Separately : Option Board
Line Input Board Line-10 (¥ 8,000) General, unbalanced high-level input terminal. Play analog signals such as CD players and tuners. Analog Disk Input Board AD-10 (¥ 50,000) Equipped with a high-performance high-gain equalizer, this cartridge can be used with any cartridge. MM/MC switching, MC input impedance and subsonic filter on/off can be set by the internal DIP switch. MM Gain : 29 dB Input impedance : 47k Ω MC Gain : 60 dB Input impedance : 10, 30, 100 Ω switching