Description
Description of item This stereo control amplifier has achieved a high level of perfection in terms of both characteristics and sound quality by approaching the circuit technology, materials, and mechanisms that form the three elements of the amplifier to the best of our ability at the present time.The MC head amplifier section consists of a base-grounded push-pull amplifier, and the linearity is improved by cascode connection. Since the base-grounded amplifier performs only voltage amplification by impedance conversion, the current supplied from the power supply is only the DC bias current, and there is no fluctuation due to the music signal. Therefore, it is not easily affected by the power supply, and its effect on the power supply is also very small.The equalizer amplifier section has a differential amplifier with dual FETs in the first stage. This FET has uniform electrical characteristics, good thermal balance, and is specially designed to have large mutual inductance and small feedback capacitance, ensuring good S/N and stable operation. In addition, each element is connected in a cascode bootstrap connection, which further reduces the apparent feedback capacitance, improves high-frequency characteristics, and makes it less susceptible to power fluctuations.The second stage is a differential amplifier using PNP transistors. Like the first stage, a cascode connection is used to equalize the collector loss of both differential pair transistors to prevent temperature drift, improve linearity, and reduce distortion. The output stage is a Darlington-connected emitter follower PP type so that it can handle a certain amount of load.The only difference in gain between the two amplifier circuits, the input buffer amplifier section and the flat amplifier section, is due to the difference in feedback resistance. Also, the only difference from the equalizer amplifier circuit is the configuration of the feedback element and first stage FET.The input buffer amplifier is a DC amplifier with 100% negative feedback and a gain of 0dB.It receives the input at high impedance, drives the attenuator and balancer at low impedance, and is used to prevent deterioration of characteristics when inputting Tuner or Aux. It has been.In addition, the flat amplifier is a DC amplifier with a gain of 20dB, and the output series resistance is as small as 100? to prevent deterioration of frequency characteristics due to connection cord capacitance, making it compatible with a wide range of load conditions.When multiple tape recorders are connected and the source signal is sent to Rec out, an overload occurs, or when the power is turned off with tape recorders connected, the input transistor of the recorder acts as a non-linear element. To prevent deterioration in sound quality, the TA-E900 has a buffer amplifier with a gain of 0 dB installed.The secondary output of the power transformer is rectified by a high-speed diode and then stabilized by a constant voltage circuit.The constant voltage circuit consists of a differential two-stage error amplifier circuit and an emitter follower, and in combination with a highly stable low current power supply, achieves high ripple rejection and low output impedance characteristics.The resistor of the attenuator and balancer is a metal coating deposited on an alumina substrate, and the conductor in contact with the slider is gold plated. In addition, the resistance value is reduced to 3k? to suppress thermal noise and prevent deterioration of high frequency characteristics due to the influence of distributed capacitance.The body is also made of die-cast zinc and aluminum, which acts as a shield.The amplification element uses an audio element that fully satisfies various characteristics such as linearity, frequency characteristics, input capacitance, and feedback capacitance. In addition, the resistors are carefully selected from those with good temperature characteristics, tolerance, and distortion (10kHz third harmonic) in terms of sound quality. In particular, the resistors used in the signal path are made with a sufficient margin for the allowable power, and are connected in series or in parallel depending on the location.In order to prevent mechanical resonance and loss due to applied voltage, film capacitors are tightly wrapped around the film and fixed, and the electrodes and film themselves are selected to have excellent mechanical strength and electrical properties. I am.For the rectifying electrolytic capacitor in the power supply section, high-purity aluminum foil is used for both the anode foil and the cathode foil, and a chemical conversion method that is most suitable for the sublayer film in terms of sound quality is used, and a high-speed, low-distortion type electrolyte is used. We have carefully considered the materials from the terminals to the plating, and have adopted materials that have been improved through repeated consideration, such as eliminating magnetic materials.First-class oxygen-free copper (copper purity of 99.99% or more) is used as the conductive material for printed circuit boards and wiring materials.The construction of the TA-E900 employs a configuration in which the left and right channels are completely separated, including the power supply section.Furthermore, by arranging elements and components along the signal flow and directly attaching them to the printed circuit board, we avoid routing wires and suppress signal interference not only between the left and right channels but also within the same channel.In addition, the attenuator and balancer are housed in a single common case for the left and right sides, and a shield plate is placed between them to improve separation without impairing left and right interlocking. The switches that change the signal system are operated by links.The input and output terminals are concentrated in one place, and by concentrating these grounds, the difference in ground potential (earth potential) is extremely small, eliminating mutual interference.Considering that mechanical vibrations have a negative impact on electrical circuits, we have implemented a thorough anti-vibration structure.First of all, we have adopted a robust chassis structure based on a thick aluminum frame to minimize the vibration of the printed circuit board and parts. A modular system is used in which the amplifier circuit is made into a unit and the entire unit is made of resin. This resin has excellent thermal conductivity and prevents thermal distortion of each part due to fluctuations in power consumption.The product is everything shown in the photo. Please be sure to check the photos.We also have many other items for sale. situationCondition rank B: No noticeable scratches or stains?Main specificationsModel stereo preamplifierCircuit methodHead Amplifier: Cascode connected base grounded complementary push-pull amplifierequalizer amplifierinput buffer amplifierFlat amplifier first stage: Cascode bootstrap differential amplifier2nd stage: Cascode connection differential amplifierCascode connected current mirror load Output stage: Darlington connection emitter followerSingle-ended push-pull output(The equalizer is NF type)Power supply section: Constant voltage power supply with independent left and right 2-stage differential detection amplifierInput sensitivity/Impedance Phono1:2.5mV/50k?/100pHPhono1(Head amp 40?):0.2mV/4?Phono1(Head amp 4?):0.035mV/4?Phono2: 2.5mV/25k?, 50k?, 100k?/100pF, 200pF, 400pFPhono2(Head amp 40?):0.2mV/4?Phono2(Head amp 4?):0.035mV/4?Tuner, Aux, Tape 1, 2: 150mV/50k?Maximum allowable input (1kHz) Phono1:180mVPhono1(Head amp 40?):15mVPhono1(Head amp 4?):2.5mVPhono2:180mVPhono2 (Head amp 40?): 15mVPhono2 (Head amp 4?): 2.5mVTuner, Aux, Tape1, 2:12VS/N(IHF-A network) Phono1:84dBPhono1 (Head amp 40?): 72dB (input conversion noise -158dB/V)Phono1 (Head amp 4?): 65dB (input conversion noise -158dB/V)Phono2:84dBPhono2 (Head amp 40?): 72dB (input conversion noise -158dB/V)Phono2 (Head amp 4?): 65dB (input conversion noise -158dB/V)Tuner, Aux, Tape1, 2:102dB output level/Impedance Rec out1, 2: 150mV (max. 12V)/100?Output1, 2: 1.5V (max. 12V)/100?Harmonic distortion rate 0.005% or less (at 8V output)Cross modulation distortion rate 0.005% or less (at 8V output, 60Hz:7kHz=4:1)Frequency response Phono1, 2: RIAA curve ±0.2dBTuner, Aux, Tape 1, 2: DC ~ 300kHz +0 -1dBFilter (Phono input) Low: 12dB/oct (cutoff frequency 15Hz)Residual noise 12?V (IHF-A network)Auxiliary power outlet Switched: 1 system, maximum 450WUnswitched: 1 line, maximum 450WPower supply AC100V, 50Hz/60HzPower consumption 18WExternal dimensions Width 480x Height 105x Depth 455mmWeight 13kgRack mount: Possible with JIS standard rack (installation pitch 50mm)?The condition of the product is that there are no noticeable scratches or stains.There is a whitish area in the gap between the wiring ports on the top board.There is a white scratch on the edge above function on the front.There is some scratches on the non-slip bottom.Please consider considering the above situation.Simple operation has been confirmed.It has only been confirmed that the sound comes out when connected to the AUX input with a par amplifier for operation confirmation.For remote delivery areas, additional fees will be charged. Import duties,taxes and charges are not included in the item price or shipping charges. These charges are the buyers responsibility. These charges are normally collected by the delivering freight(shipping) company or when you pick the item up. -do not confuse them for additional shipping charges. We do not mark merchandise values below value or mark items as gifts. -US and International government regulations prohibit such behavior.
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