McIntosh MC602

Commentary

Equipped with a double balance circuit and output auto-former, this model was announced as the best Macintosh stereo power amplifier.

The power amplifier circuit is equipped with a double-balanced circuit. This circuit consists of four amplifiers, one symmetrical circuit above and one symmetrical circuit below the balanced circuit, which usually consists of two symmetrical circuits. This circuit has almost perfect balance from input to output and achieves high fidelity amplification with virtually no distortion.
In addition, the negative feedback is minimized as much as possible, and odd harmonic distortion, which is particularly unpleasant sound, is suppressed to obtain low 歪大 output.

Forty eight output power transistors are used and fixed to four large heat sinks for cooling by natural air cooling only.

High-quality parts are strictly selected and used.
The active device uses a transistor with a stable gain over the current range to be operated, and the output transistor uses a wide safe operating range with uniform current gain, high current gain bandwidth, low output capacitance.
As passive elements, high-precision metal film resistors with excellent temperature coefficient and low dielectric absorption film capacitors are used.

The transformer installed in the MC602 is suitable for 2 Ω, 4 Ω and 8 Ω loads, and can transmit low-distortion transmission over a range of frequencies far exceeding the audible range, and can supply peak current over 150A even for fluctuations in speaker impedance that can drop to 1 Ω or 2 Ω.

The power supply section is equipped with a large power transformer, a full-wave rectifier bridge diode, a large-capacity filter capacitor that supplies 200 joules of current, and an independent power supply for both the positive and negative sides of the balance circuit.

It is equipped with a power guard. When the total harmonic distortion exceeds 0.3%, the amplifier gain is controlled to keep the distortion of the amplifier output low. This circuit operates only when the amplifier is requested to have power exceeding the designed value.

The sentry monitor system prevents catastrophic current flow in the event of a short or very low load impedance.

With thermal protection, the temperature sensor senses overheating due to under-ventilation or over-temperature loads, mutes the input and automatically recovers when the amplifier cools.

With in-rush protection, stress to the power transformer due to rush current when the power is turned on is removed.

Equipped with DC protection, the autotransformer cuts DC when DC leaks to the output.

The built-in turn-on delay delays the operation of the amplifier for approximately two seconds when the power is turned on, preventing signals from other devices that cause unpleasant noise and protecting the speaker from damage.

Equipped with the traditional Blue Eyes Power Meter, it can measure voltage and current electronically and display the actual power output.
This meter can be displayed in three different ways : the WATTS position, which displays from 6 mW to 600W/1200W/2400W ; the HOLD position, which locks at the maximum peak when there is continuous peak power and then returns slowly to the rest position ; and the LIGHTS OFF position, which turns off the backlight and has the same function as the WATTS position.

Each terminal is gold-plated to improve reliability.

It is equipped with a remote power control which can turn the power on/off from the control amplifier of Macintosh.
It also prevents overloads such as circuit breakers and blown fuses.

Model Rating

Type	Stereo power amplifier
Rated output	600W + 600W (2 ohm, 4 ohm, 8 ohm load, 20 hz to 20 khz, sine wave)
Output Voltage (RMS)	34.6V(2V) 49 v (4 Ω) 69.3 V (8 Ω)
Rated output bandwidth	20 Hz to 20 kHz
Output load impedance	Stereo : 2 Ω, 4 Ω, 8 Ω
Input sensitivity	Unbalanced : 2.45 v Balance : 4.9 v
Input impedance	10k Ω
Frequency characteristic	20 Hz ~ 20 kHz + 0 -0.25 dB 10 Hz ~ 100 kHz + 0 -3.0 dB
Signal-to-noise ratio (A-weighted)	Unbalance : 93 dB (120 dB below rated output) Balance : 97 dB (124 dB below rated output)
Total harmonic distortion	0.005% or Less (250 mW ~ Rated Output)
Intermodulation distortion (SMPTE)	Maximum 0.005% (Instantaneous Peak Power Output <Rated Output x2)
Wideband damping factor	100 (8 Ω output)
Power Guard	Clipping prevention Total harmonic distortion factor <2% (overdrive <14 dB, 1 kHz)
Pwer	100 VAC, 50Hz/60Hz, 12A (UL/CSA Standard)
External dimensions	Width 445x Height 310x Depth 537 mm
Weight	69.8kg