QUAD 405-2
¥ 198,000 (around 1986)
Commentary
Improved stereo power amplifier based on 405.
The 405 / 2 is based on the 405 and has been improved to greatly increase the driving capability against load fluctuation.
To solve the problems caused by the normal load line protection circuit, the QUAD has its own protection circuit, which smoothly reduces the abnormal current to within the safe operating range of the transistor and protects against short circuit. It is also integrated with the speaker protection circuit, which prevents the speaker from being destroyed by the trouble inside the amplifier.
A current damping circuit developed by QUAD is adopted.
This circuit consists of a single-output, small-power pure class A amplifier that amplifies voltage and supplies power for small signals, and a push-pull circuit with complete class B operation called a damper circuit. For small signals, current is supplied from the small-power pure class A amplifier to the load, and when the signal level increases, the damper circuit operates to supply a large current to the load.
The low-power pure class A amplifier always detects and corrects errors between input and output signals and cancels all distortion at the output stage. In addition, it has low power loss, eliminates the need for idling adjustment, temperature compensation, and offset adjustment, and has excellent stability over time.
Model Rating
| Type | Stereo power amplifier |
| * Compensation value when both channels are driven simultaneously. | |
| Power and distortion factor (8 Ω load, sine wave input) |
0.01% or Less (at 100 Hz, 100W output) 0.01% or Less (at 1 kHz, 100W Output) 0.01% or Less (at 10 khz, 100W output) |
| Output internal impedance | 3.3 μ H in series with 0.03 Ω |
| Offset voltage | 7 mv or less |
| Frequency Response (1 kHz Standard) | Low frequency : -1dB at 20 Hz High frequency : -0.1 dB at 20 Hz, -3dB at 50 kHz |
| Input sensitivity | 0.5 V (8 Ω Load, 100W Output) |
| Input impedance | 20k Ω / 220 pf |
| Slew rate | 0.1 V / μ s |
| Maximum input limit | If the input signal is up to + 20 dB, it will be restored immediately. |
| Crosstalk (at 1k Ω input load) |
80dB(100Hz) 70dB(1kHz) 60dB(10kHz) |
| Signal-to-noise ratio | -96dB (for A correction) -93dB (uncorrected) |
| Protection circuit | Electrically operated by current control circuit. The peak output current is limited to 8.5A, and the output short-circuit is limited to 3.1A. If both outputs are short-circuited simultaneously for an extended period of time, overheating may result and malfunction may result. |
| Pwer | 100 ~ 130 VAC / 200 ~ 250 V, 50Hz/60Hz |
| Power consumption | 30W ~ 350W (depending on input level) |
| External dimensions | Width 340.5x Height 115x Depth 195 mm |
| Weight | 9kg |