Audio Database

Image of Integra A-1E ver. 2
Commentary

Based on the A-1E of the Quest Integra series, this pre-main amplifier was developed by reviewing the basic operation of the circuit and the elements used.

In general amplifiers, phase correction is used to suppress high-frequency characteristics in order to prevent problems such as oscillation. This deteriorates the naked characteristics of the amplifier and adversely affects sound quality.
The A-1Ever2 realizes excellent frequency characteristics extending to 200 kHz or more by reducing the phase correction as much as possible. The solution is to install the phase correction circuit in a circuit with little influence on sound quality and to use carefully selected parts.

The output filter coil has been eliminated, and combined with flat damping technology that ensures a flat warping factor characteristic in the audible band, a stretchy high range characteristic is achieved.
We have also succeeded in reducing the negative feedback of the overall by reducing the distortion factor in the high frequency range.

By lowering the output impedance of the circuit, the adverse effect of the electromotive force caused by the inertia of the speaker on the operation mechanism of the amplifier circuit is eliminated.
In addition, a real-time temperature compensation circuit is adopted to reduce bias fluctuation due to changes in load and music signal, and to improve stability of operation.

The capacitor in the power supply section is equipped with a blue capacitor, development number 923, which has been developed for three years to achieve both energy and high resolution.
In addition, the power transformer is equipped with a toroidal type LASER with ultra-low leakage flux characteristics and an inverter.
In addition, it uses a 15A-type bridge rectifier diode with a margin.

The front panel is 9 mm thick, highly rigid, non-magnetic all-aluminum extrusion molded monocoque chassis. This chassis is finished to an accuracy of ± 0.5 mm by high-precision machining technology. By providing many ribs on the inside and outside, the rigidity of the chassis is improved and unwanted resonance is reduced.
In addition, the transformer, heat sink, and printed circuit board are mounted in isolation with the chassis using an insulator. The insulator supporting the chassis is DuPont Corian, and the concept of non-resonance and high rigidity is thoroughly implemented.

The speaker terminal uses the well-established WBT terminal.
In addition, the PIN terminal uses newly manufactured high rigidity brass machined gold plated terminal, and the rear panel is fixed to the rigid with 2 point stops for 1 pair of left and right.
The space between the left and right terminals is 18 mm, making it possible to use thick PIN plugs.

It uses thorough parts such as high-precision dual transistor for measuring instrument in differential amplifier, high-precision resistance of ± 0.1% error, low-distortion volume, Radarstein Film Con, 70 μ m copper foil printed circuit board, etc.

Model Rating
Type Pre-main amplifier
Rated Output (20 Hz ~ 20 kHz) 50W + 50W (8 Ω)
85W + 85W (4 Ω)
Dynamic Power (1 kHz) 80W + 80W (8 Ω)
140W + 140W (4 Ω)
230W + 230W (2 Ω)
Total Harmonic Distortion Factor (20 Hz to 20 kHz, 8 Ω) 0.02% (at rated output)
0.01% (at 10W output)
Intermodulation distortion factor (70 Hz : 7 kHz = 4 : 1, 8 Ω) 0.02% (at rated output)
Powerbandwidth 10 Hz to 100 kHz (IHF-3dB, THD 0.2%)
Damping factor 300 or More (8 Ω, 20 Hz to 20 kHz)
Slew rate 80 v / μ s
Gain / phase 36 dB / in-phase
Frequency characteristic 10 Hz ~ 100 kHz + 0 -1.5 dB
S/N ratio (A-Weighted, input short) CD:112dB
Channel separation 75 dB (CD, 1 kHz-terminated, 100 Hz to 10 kHz)
Input Sensitivity / Impedance CD, Tuner, Line1, 2, Tape Play : 300mV/25k Ω
Recorded output Tape Rec Out:300mV
Power supply voltage 100 VAC, 50Hz/60Hz
Power consumption (Electrical Appliance and Material Control Law standard) 155W
External dimensions Width 435x Height 85x Depth 374 mm
Weight 9.3kg