Audio Database
C-275V
Commentary

Based on the C-290V technology, the entire C-275 circuit has been refined to further enhance the control amplifier.

It 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 the current, and the output signal is generated by I-V conversion of the current with a trans-impedance amplifier. Because the impedance of the feedback input part is low, phase rotation hardly occurs, and various characteristics can be greatly improved with a small amount of NFB.

Bridge feedback type 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.
In the C-275V circuit, the outputs of two pairs of amplifiers are fed back to the other side, and the + - symmetric signal is sent out with low impedance. In this circuit, the + - symmetric signal is floating 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 section uses a pure complimentary service push-pull circuit, which is composed of discrete parts using a current feedback amplifier circuit to reduce phase compensation at each stage.

The signal transmission circuit uses a printed circuit board made of Teflon (glass cloth fluorine resin).
Teflon has advantages such as low dielectric constant (high propagation speed), very low leakage current (low loss), excellent heat resistance and high frequency characteristics. By using this Teflon substrate in audio circuits, SN in the sense of hearing is improved.

The power transformer and filter condenser are independent on the left and right sides, and the configuration is completely monaural.
In addition, all unit amplifiers are equipped with wide-band low-impedance power supplies to prevent mutual interference between amplifiers.

The amplifier circuit of C-275V consists of a total of four unit amplifiers on the left and right sides, such as line input and balance output, each of which has its own power supply.
These unit amplifiers are housed in a thick aluminum housing so that they do not interfere with each other and are firmly fixed to prevent resonance due to vibration.

The 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 type, and low contact resistance and high durability are realized.

An additive active filter is used for tone control.
In this method, the original flat signal passes through as it is, and when the characteristic is to be changed, the characteristic is made as necessary and is changed by adding or subtracting from the flat signal.

Built-in dedicated headphone amplifier circuit for sound quality.

Equipped with an output phase switch button, a compensator with three selectable characteristics, and a subsonic filter.

It comes with a remote commander that can change volume and input.

The C-275V is a line-only configuration, but record playback is possible by adding the AD-275V phono equalizer unit (sold separately) from the rear panel side.
The printed circuit board is made of Teflon (glass cloth fluorine resin), which is stored in a sturdy aluminum case to reduce external influence. The DIN connector is used for connection to the main body, and the input terminal and amplifier circuit are connected at the shortest distance to prevent the S / N ratio from decreasing.
This phono equalizer unit is equipped with a dedicated input circuit for each MM/MC cartridge. Three types of MC input impedance and two types of gain can be selected.

The AD-275V cannot be used with models other than C-275V and C-275.
AD-275 can also be used for C-275V.

Model Rating
(Analog disk characteristics show when AD-275V is added)
Type Stereo Control Amp
Frequency Response
Balanced, Unbalanced : 3 Hz to 300 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 : 4.0mV/1.0mV/47k Ω
AD MC/60dB : 0.25mV/0.063mV/10 Ω, 30 Ω, 100 Ω switching
AD MC/66dB : 0.125mV/0.0315mV/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/200 Ω
S/N, input conversion noise
Input Short A - Correction EIA S/N
S/N at rated output Input Conversion Noise
AD MM: 90dB -138dBV 91dB
AD MC/60dB: 79dB -151dBV 84dB
AD MC/66dB: 75dB -153dBV 84dB
Balanced: 114dB -126dBV 96dB
Unbalanced 116dB -128dBV 96dB
Maximum power level
(0.005% distortion rate, 20 Hz to 20 kHz)
Balanced, Unbalanced output : 6.0 v
Tape rec at AD input : 6.0 V
AD Maximum Input Voltage
(0.005% strain rate)
MM input:125mV
MC(60dB/66dB) input:8mV/4mV
Minimum Load Impedance Balanced, Unbalanced output : 600 ohms
Tape rec : 10k Ω
Gain Balanced, Unbalanced input → Balanced, Unbalanced output : 18 dB
Unbalanced input → Rec output : 0 dB
AD MM input → Balanced, Unbalanced output : 54 dB
AD MM input → Rec output : 36 dB
AD MC (60/66dB) input → Balanced, Unbalanced output : 78/84dB
AD MC (60/66dB) input → Rec output : 60/66dB
Compensator
(Volume -30dB)
1:+3dB(100Hz)
2:+6dB(100Hz)
3 : + 6 dB at 100 Hz, + 6 dB at 20 kHz
Subsonic Filter 25 Hz, -12dB/oct
Attenuator -6dB, -20dB, -30dB
Power Supply 100 VAC, 50Hz/60Hz
Power Consumption 25W
Maximum External Dimensions 475 mm wide x 150 mm high x 404 mm deep
When adding AD-275V : Depth 413 mm
Weight 21.7kg
When AD-275V is added : 22.5 kg
Attachments Remote Commander RC-26
Sold Separately Phono Equalizer Unit AD-275V (¥ 100,000)