Description
Accuphase C-280L Control Amplifier AC100V/117V/220V/240V 50Hz/60Hz From JapanDescriptionThis stereo preamplifier has been improved from the C-280 by equipping it with a full-fledged balanced line amplifier with a two-amplifier configuration and 10 input terminals. In order to achieve higher quality balanced transmission, which was previously achieved with a transformer, this preamplifier has a two-amplifier balanced transmission line amplifier with an amplifier on each of the hot and cold sides. The same complementary differential push-pull amplifier circuit is used for each amplifier. The volume is also controlled by a precision four-gang volume (linked to the left and right channels) that is completely separated into hot and cold. In addition to the Class A push-pull amplifiers at all stages, the cascode system is further advanced, and FETs are used on the load side of the cascode-connected amplifiers, eliminating the need to worry about base current leakage when using bipolar transistors, resulting in a playback sound with less coloration. All unit amplifiers use a DC servo system using ICs, which detects direct current generated at the output and feeds it back to the input, preventing DC drift.The DC servo system and precise design have virtually eliminated DC drift, and all signal systems from MC input to output are directly connected. The circuit board is firmly fixed with screws, and the Class A output element and constant-voltage power supply element are fixed in close contact with the housing to dissipate heat, preventing resonance due to induction and vibration. The power supply section uses dedicated power transformers for the left and right channels, resulting in a mono construction that is completely independent both electrically and structurally. In addition, to achieve low impedance over a wide frequency range, a total of six multiple power supplies are used, with a dedicated constant-voltage power supply for each unit amplifier.The unit amplifiers and constant-voltage power supply sections are housed in thick aluminum housings and wired in the shortest possible distance, preventing an increase in power supply impedance in the high range. In order to configure the shortest and straightest signal path, relays are installed in all signal paths where switches are required, and these relays are electronically controlled by a logic circuit to perform switching.The relays used are sealed relays filled with nitrogen gas, which were developed specifically for audio and communication equipment, and the contacts are crossbar twin type made of gold and silver-palladium alloy, which is of high quality with low contact resistance and high durability. Furthermore, to further increase reliability, four circuits are used in parallel for the low-level signal path to ensure completeness. The basic circuit of the equalizer amplifier section is almost identical to that of one side of the line amplifier, but low-noise elements are carefully selected for the input stage of the differential amplification. The elements that create the RIAA playback characteristics that affect the sound quality are composed of a network combining resistors and capacitors, and this section uses a silvered mica capacitor that was developed specifically for audio use. This capacitor has a special processing and structure in which a thin silver film is formed on a piece of refined high-purity mica by the screen method, and then a glass pattern (thin glass layer) is printed on it. This increases the corona discharge starting voltage, allowing the signal to pass stably even at pulse-like high voltages. In addition, the way the lead wires, which affect the sound quality, are drawn out is directly connected to the edge of the silver film, so there is no deterioration. In the head amplifier section, low-noise elements are used in the input circuit, and the impedance of the NFB loop is reduced to reduce resistance noise. In addition, to avoid the influence of noise generated by the DC servo, feedback is not only directly to the negative side of the differential amplifier, but also to the base of the constant current source. This almost completely eliminates the influence of servo-related noise, achieving a signal-to-noise ratio close to the theoretical limit. In order to support various MC cartridges and allow for fine control of sound quality, the MC input impedance can be switched between three levels: 10?, 30?, and 100?. In addition, a gain switch is provided to provide a gain of 32dB in addition to the normal head amplifier gain of 26dB for low-output MC cartridges. Each input jack is specially made and used with high-quality rhodium plating, with an emphasis on long-term deterioration. It is 1?m thick and has a high degree of durability that can withstand 100 million strokes, and has excellent corrosion resistance, so it maintains good contact for a long time. It is equipped with an attenuator that can instantly lower the volume without changing the volume.It uses a three-step rotary system that reduces the level to -? (silence) when turned counterclockwise, and -20dB and -30dB when turned clockwise. It is equipped with independent left and right attenuator-type level controls that perfect channel balance and allow you to control the positioning even if the listening point is shifted. It is equipped with functions such as a monitor switch that allows you to record, play, and monitor a tape recorder, a compensator that increases the volume of the low-frequency range, and a subsonic filter. It uses a heavy persimmon wood case with a gold-tone scratch hairline panel. Frequency responseCD, Tuner, Line, Tape Play: 1.0Hz to 350kHz +0 -3.0dB20Hz to 20kHz +0 -0.2dBCD, Line (Balanced Input): 1.0Hz to 700kHz +0 -3.0dBAD: 20Hz to 20kHz +0 -0.2dBInput sensitivity/impedance(Rated/EIA output 0.5V) AD (Head Amp off): 4.0mV/0.5mV/47k?AD (Head Amp +26dB): 0.2mV/0.025mV/10?, 30?, 100?AD (Head Amp +32dB): 0.1mv/0.0125mV/10?, 30?, 100?CD, Line, Tuner, Tape: 252mV/31.5mV/20k?CD, Line (Balanced): 252mv/31.5mV/40k? (20k?/20k?)Rated output/impedance Output (Balanced): 2.0V/50? (25?/25?), XLR type connectorOutput (Unbalanced): 2.0V/1?, RCA phono jackTape Rec: 126mV/200? (AD), RCA phono jackS/N/Input conversion noiseInput short IHF-A compensationInput terminal Rated input S/N Input conversion noise EIA S/NAD (Head Amp off): 90dB -140dBV 86dBAD (Head Amp +26dB): 78dB -152dBV 76dBAD(Head Amp +32dB): 72dB -152dBV 76dBCD, Line, Tuner, Tape: 115dB -128dBV 95dBCD, Line(Balanced): 115dB -128dBV 95dBMaximum output level(0.005% distortion, 20Hz-20kHz) Output(Balanced):10.0VOutput(Unbalanced):10.0VTape Rec:19.0V(AD)Maximum input voltage(1kHz, 0.005% distortion) AD(Head Amp off):300mVAD(Head Amp +26dB):15mVAD(Head Amp +32dB):7.5mVMinimum load impedance Output (Balanced): 600? (300?/300?)Output (Unbalanced): 1k?Tape Rec: 10k?Gain CD, Line (Balanced) ? Balanced Output: 18dBCD, Tuner, Line, Tape Play ? Output: 18dBCD, Tuner, Line, Tape Play ? Rec Output: 0dBAD (Head Amp Off) ? Output: 54dBAD (Head Amp Off) ? Rec Output: 36dBAD (Head Amp +26dB) ? Output: 80dBAD (Head Amp +26dB) ? Rec Output: 62dBAD (Head Amp +32dB) ? Output: 86dBAD (Head Amp +32dB) ? Rec Outpu: 68dBLoudness Compensator(Volume Adjustment -30dB) 1: +3dB (100Hz)2: +8dB (100Hz), +6dB (20kHz)Subsonic filter 10Hz, -18dB/octAttenuator -20dB, -30dB, -?Semiconductors used Transistors: 219FETs: 58ICs: 26Diodes: 174Power supply AC100V/117V/220V/240V, 50Hz/60HzPower consumption 75WExternal dimensions Width 468 x Height 171 x Depth 396mmWeight 18.1kg*The voltage at the time of shipment is 100V, so please adjust the internal voltage to match the voltage in your country.ShippingWe will ship the item by FedEx, DHL, UPS, Japan Post (EMS/Airmail) and provide the tracking number. Shipping is only available to the address registered.Please note that any address not registered is not acceptable to ship. Shipping is possible from Monday to Friday.Saturdays, Sundays, and Japanese holidays are not available because the transportation company is closed.International Buyers - Please Note:Import duties and taxes are not included in the item price or shipping cost. Please check with your country’s customs office to determine these additional costs prior to bidding or buying. Additionally, if the delivery address is in a remote area, there may be additional charges by FedEx or DHL. If such charges occur, you may be asked to pay an additional $15 to $20.
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