Accuphase E-407
¥ 400,000 (released in October 1999)
Commentary
This is a new reference model pre-main amplifier developed with the aim of becoming the best pre-main amplifier by introducing the design technology cultivated by Acphase, the latest circuit and high-quality elements.
The output device uses a multi-emitter high-power audio power transistor with excellent high-frequency characteristics, linearity of current amplification factor, switching, and other characteristics.
This element is composed of 3 parallel push-pull to reduce impedance, and is fixed on a large heat sink to effectively dissipate heat.
Both the preamp section and the power amplifier section use a current feedback amplifier circuit with superior high-frequency characteristics.
This circuit first detects a current by reducing the impedance of the input terminal on the feedback side, and converts the current to I-V (current-voltage) with a transimpedance amplifier to produce an output signal. In this circuit, since the impedance of the input terminal on the feedback side is extremely low, phase rotation hardly occurs and there is almost no need for phase guarantee.
As a result, various characteristics can be greatly improved with a small amount of NFB, resulting in excellent dynamic characteristics such as start-up and natural energy response in terms of sound quality.
The line amplifier section consists of discrete parts using a current feedback amplifier circuit.
It is based on the AccuPhase original differential-pure complimentary service push-pull and has a simple configuration with a single-ended push-pull emitter-follower at the output stage.
As a result, the phase compensation of each stage is light and the sound quality is improved.
In order to configure the shortest and straight signal path, a logic relay control method is adopted that electronically controls the relay.
The relay used for this is a sealed type for the communication industry, and the contact is gold-plated and cross-over twin type to realize low contact resistance and high durability.
An additive active filter method is used for tone control.
In this method, the original flat signal passes straight through, and the characteristics are created separately as necessary and adjusted from the flat signal.
The power supply section is equipped with a large toroidal transformer with a large power capacity of approximately 600 VA. In addition, it is fixed to an aluminum case with a high-efficiency heat radiation structure using a filler with excellent heat conduction and vibration damping effect, thereby shielding the external influence.
Because a thick copper wire is wound around a doughnut-shaped core, the toroidal transformer has features such as extremely low impedance, small size and high conversion efficiency. The E-407 uses a Max Ring-type toroidal transformer. Because the cross-section of the iron core is close to a circle and the coil is also close to a circle, adhesion is good. Therefore, loss and weight can be reduced, leakage flux is small, and groaning and vibration are reduced. In addition, by making the cross-section of the iron core small and the weight ratio of the copper wire large, iron loss and inrush current are kept small.
In addition, two 33,000 μ F aluminum electrolytic capacitors for filters are installed.
A special amplifier for headphones is installed to give consideration to the sound quality of headphones.
You can turn off the output to the speakers with the Speaker Selector and adjust the headphone output with the Main Volume.
The speaker terminal is machined out of solid brass and made into a gold plate, and is equipped with a large speaker terminal that can handle thick cables.
There are two speaker outputs, which can be switched or connected by bi-wiring.
It is equipped with an analog large peak power meter of logarithmic compression type.
This meter also has an on/off switch for lighting.
Equipped with 2 balanced inputs.
It is equipped with a separate switch that can use a preamp and a power amplifier independently, and an input / output terminal.
It comes with a remote commander that allows volume manipulation and input switching.
It has a slot for an option board and can be expanded with an Accuphase Analog Bus (AAB) board depending on the application.
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Model Rating
| Type | Integrated stereo amplifier | |||||||||||||||||
| Rated continuous average power (both channel operation, 20 Hz to 20 kHz) |
260W/ch (4 Ω) 220W/ch (6 Ω) 180W/ch (8 Ω) |
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| Total harmonic distortion factor (both channel operation) | 0.02% (4 Ω ~ 16 Ω Load) | |||||||||||||||||
| IM distortion factor | 0.01% | |||||||||||||||||
| Frequency characteristic | High Level input, Main input : 20 Hz ~ 20 kHz + 0 -0.2 dB (at rated continuous average output) 2 Hz ~ 150 kHz + 0 -3.0 dB at 1W Output |
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| Damping factor | 120 (8 Ω load, 50 Hz) | |||||||||||||||||
| Input Sensitivity / Impedance (Rated Output / EIA1W Output) |
High Level input : 158mV/11.2mV/20k Ω Balanced input : 158mV/11.2mV/40k Ω Main input : 1.58V/112mV/20k Ω |
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| Output Level / Impedance | Pre output : 1.58V/50 Ω (at rated continuous output) | |||||||||||||||||
| Gain | High Level input → Pre output : 20 dB Main input → output : 28 db |
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| S/N, input conversion noise |
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| Tone control | Bass (300 Hz) + / - 10 dB (50 Hz) High tone (3 kHz) : ± 10 dB (20 kHz) |
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| Loudness compensator | + 6 dB (100 Hz, Volume -30dB) | |||||||||||||||||
| Attenuator | -20dB | |||||||||||||||||
| Power meter | Logarithmic compression type peak level display Direct reading of output at dB scale and 8 Ω load |
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| Load impedance | 4 Ω ~ 16 Ω | |||||||||||||||||
| Headphone port | Applicable Impedance : 4 Ω ~ 100 Ω | |||||||||||||||||
| Pwer | 100 VAC, 50Hz/60Hz | |||||||||||||||||
| Power consumption | 45W (non-input) 410W (Electrical Appliance and Material Control Law) 605W (at 8 Ω load rated output) |
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| Maximum external dimensions | Width 475x Height 180x Depth 423 mm | |||||||||||||||||
| Weight | 23.7kg | |||||||||||||||||
| Attachment : Remote Commander RC-20 | ||||||||||||||||||
| Remote control system | Infrared pulse system | |||||||||||||||||
| Pwer | DC 3V | |||||||||||||||||
| Dry battery | AA Type, 2 pcs | |||||||||||||||||
| Maximum external dimensions | 55 mm wide x 194 mm high x 18 mm deep | |||||||||||||||||
| Weight | 100g (including dry batteries) | |||||||||||||||||
| Optional Board Sold Separately | ||||||||||||||||||
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