SANSUI B-2302 VINTAGE

Commentary

This is a stereo power amplifier that focuses on all the elements of circuits, parts, and mechanisms to achieve a balance of sound in a higher dimension.

To realize a true balance amplifier, the B-2302 VINTAGE uses an α -X balance circuit composed of three components : a balance output stage, a NEW diamond differential circuit, and a balance power supply.

The balanced output stage drives the speakers equally from both the hot and cold sides. As a result, there is no fundamental degradation of sound quality caused by grounding, and the distortion caused by the back electromotive force of the speakers is eliminated, enabling a powerful and accurate speaker drive. In the case of a general BTL connected amplifier, there is a possibility that the symmetry of the output signal will be lost due to the characteristic difference because the two amplifiers are operated independently. However, the α -X balanced circuit does not have this problem.
The NFB nfB has a unique balance feedback configuration. It is cross-fed from the hot-side output to the cold-side input and from the cold-side output to the hot-side input. Thus, the NFB of the two amplifiers on the hot-side and the cold-side affect each other to improve the characteristics, resulting in a balanced output stage that works as one amplifier.

The NM-LAPT (Non-Magnetic Linear Amplification Power Transistor), a bipolar transistor for audio, is used for the output stage. The B-2302 VINTAGE is equipped with a custom-developed Pc200W transistor suitable for high power amplification.
This NM-LAPT has a multi-emitter structure to increase the current capacity and to narrow the base width._T(cutoff frequency) has been improved to ensure linear input / output characteristics up to the ultra-high frequency range. In addition, nickel plating, which poses a problem in sound quality, is eliminated from the chip surface, and the lead is made of non-magnetic pure copper material to eliminate harmful magnetic distortion. By the way, f of a general power transistor is eliminated._TThe NM-LAPT is approximately three times as high as 60 MHz, while the is 5 to 20 MHz.
The output stage is a balanced drive and 4-parallel push-pull configuration using 8 NM-LAPTs per channel to improve sound resolution and sense of localization.

NEW diamond differential circuit is adopted from the first stage to the driver stage.
A general balance amplifier is often equipped with a phase inverting amplifier to input a negative phase signal on the cold side in addition to the positive phase signal on the hot side. However, the NEW diamond differential circuit has a circuit configuration that does not require an inverting amplifier.
The hot-side and cold-side signals are directly input to both ends of the first stage differential amplifier with two inputs and two outputs, respectively, and are balanced and transmitted to the diamond differential circuit of the pre-driver stage. The diamond differential circuit has a balanced double-end output of two sets of four outputs and drives the output stage in a balanced push-pull drive.
In addition, in consideration of characteristics, four low-noise FETs with excellent linearity are used for the first stage and differential amplifier, and cascade connection is made by combining two low-noise FETs each with source grounding and gate grounding. As a result, high-frequency characteristics are greatly improved and stability against fluctuations in external impedance is further enhanced.
In addition, the pre-driver stage / diamond differential circuit boasts an instantaneous large current and high-speed response with a slew rate of ± 350 V / μ s, and does not generate TIM (transient intermodulation) distortion that occurs when the circuit cannot follow a large input signal with a fast rise time.

The power supply circuit uses a balanced power supply.
In a power supply circuit with a common ground, ripple contained in the supply current is returned to the signal input side via the ground of the power supply, and this causes intermodulation with the audio signal, causing IHM (Interference Hum Modulation) distortion that is harmful to sound quality.
The balanced power supply has a power transformer without a center tap and a dual bridge rectifier circuit to provide isolation from the earth. This fully closed-loop configuration eliminates problems such as noise contamination caused by the earth. The balanced power supply also reduces the noise component from the AC line, minimizing the impact on sound quality.

The parts used in each circuit are carefully selected with an emphasis on three points : maintaining high audio signal purity, maintaining long-term reliability, and enhancing the overall quality of the circuit.

The circuit components include carbon resistors with gold-plated leads / caps and OFC leads with butyl-rubber-wrapped copper foil styrene capacitors. For the emitter resistor of the output stage, a Lambda II resistor with a ceramic case and an OFC phase correction coil with a copper case are used, taking advantage of the characteristics of NM-LAPT.
In place of conventional separators made of Manila hemp or kraft paper, we have adopted a newly developed silmic electrolytic capacitor mixed with silk fiber, which has a high ability to impregnate and hold electrolytic solution, and AXF electrolytic capacitors and Sa special film capacitors with low impedance and low distortion.
The circuit board is a rolled copper plate regardless of the deposition process, and an OFC circuit board with improved bending strength and peeling strength as well as improved high-frequency signal transmission characteristics is adopted. Gold-plated OFC leads are used for the jumper leads.

The transformer used in the power supply section is a massive toroidal transformer.
The power supply capacity of this transformer is 1.4 kVA, which is one of the top class capacity comparable to power amplifiers with double output. In addition, the transformer case is filled with high-density filler, and the coil winding is equipped with unique know-how to prevent vibration and heat generation.
In addition, the rectifier diode uses a wood-plated pellet ultrafast fast recovery diode with high switching speed and little harmful ripple. The electrolytic capacitor uses a Great Pure Focus electrolytic capacitor with low-magnification etched foil and a Silmic super gold capacitor.

Canon connectors are made by Neutrik, and RCA-pin jacks and speaker terminals are made by WBT, which has undergone OFC-alloy 24-carat hardening gold plating with a machining accuracy of less than 2/100 mm.
The speaker terminal is a double-pole terminal that can be connected with a banana plug, or with a very thick speaker cable or by wiring.

For the power cable, the atomic arrangement is extremely uniform and there is no disturbance in the flow of electrons. For the sheath structure, stress-free 6N (copper purity 99.9999%) cable with vibration control measures is adopted with a specially made gold-plated plug.

For internal construction, twin monaural construction and symmetric input / output layout are used.
In this structure, the power supply, which accounts for the maximum weight of the amplifier, is placed in the center of the chassis, and the L and R power units are arranged symmetrically with the power supply between them, so that the left and right channels are completely separated and power can be supplied over an equal distance. In addition, a good balance with excellent vibration resistance is obtained.
The terminal layout of the rear panel is symmetrical and symmetric. The input terminals are located at the top and the speaker terminals are located at the bottom according to the input / output pattern of the power unit. This minimizes signal line routing inside the amplifier and enables signal transmission over the shortest distance.

The chassis of the B-0. 2302 VINTAGE uses copper for the mounting base of the transformer and capacitor, the input / output panel, the inside of the center top panel, and the inside of both side panels. In addition, the power unit uses two copper shield plates that cover the entire surface of the circuit board.
The base plate has a double structure of copper plate and copper-plated steel plate, and the insulator effect is realized by the large pure copper leg.

Power transistors are designed to be mounted individually with pure copper blocks to effectively dissipate heat while suppressing device noise, and then connected and fixed to a heat sink.

The heat sink is made of a highly rigid non-magnetic extruded aluminum material in consideration of heat radiation effect, magnetic distortion and unnecessary vibration. In addition, the entire surface of the heat sink is coated with fluorine resin. Fluorine resin has a non-polar molecular structure with high intermolecular bond strength and chemical stability that does not change properties even when exposed to high temperatures for a long period of time. In addition, it has flexibility and stretchability, and suppresses unnecessary resonance and resonance of the heat sink.

Equipped with an input selector with an off position that allows one touch switching between balanced and normal inputs.
A 6-stage attenuator type input volume composed of gold-plated lead / cap / carbon resistor is provided for each balance / normal input.

Equipped with an L/R independent LCD power meter with excellent visibility that displays the output level in real time.
This meter can be switched to a peak-hole display because it has a high tracking ability for a pulsating sound. Moreover, since the signal is sent by a floating circuit using a transformer, it does not adversely affect the amplifier section. In addition, it can be turned off with an on / off switch.

In addition to dealing with problems such as DC input, load short-circuit, and over-input, a built-in protection circuit protects the amplifier and speaker by detecting temperature rise due to abnormal operation.
It also has "High Temp", "Protector" and "Overswing" warning indicators.

There are 2 color variations, black and gold.

Model Rating

Type	Stereo power amplifier
Rated Output (20 Hz ~ 20 kHz)	300W + 300W (8 Ω)
Harmonic distortion factor	0.003% (20 Hz to 20 kHz)
Cross modulation distortion factor	0.003%(60Hz:7kHz)
Frequency characteristic	DC ~ 300 khz + 0 -3dB
Input Sensitivity / Impedance	Normal : 1V/15k Ω Balanced : 2V/10k Ω
Slew rate	± 300 V / μ sec
Rise time	± 0.5 μ sec
Signal-to-noise ratio	120dB
TIME distortion	Measurement limit value or less
Envelope distortion	Measurement limit value or less
External dimensions	Width 474x Height 215x Depth 500 mm
Weight	46.0kg