Marantz SM-7

Commentary

A power amplifier developed for Low-TIM.

The main amplifier section consists of a full DC amplifier, and the first stage employs a dual FET source follower amplifier with matching pair characteristics to prevent characteristic degradation due to impedance changes at the input stage. The main amplifier section consists of a dual Tr differential amplifier → emitter follower buffer amplifier, and the power amplifier stage consists of a three stage Darlington circuit with a newly developed Super Hi-fT Tr parallel push-pull.
This Super High-fT transistor was born based on the Low-TIM concept, and is the latest emitter ballast type power transistor at that time, which can be called the crystal of LSI process technology and high-frequency Tr technology.
In spite of the large Pc of 200W, the fT shows 60 mhz. It has excellent high-frequency characteristics, switching characteristics, and stable amplification performance with a margin to the ultra-high band. This is a custom-made Marantz product. As a result, the high-speed response of the SM-7 is remarkably improved over the wide band from the ultra-high band to the ultra-low band.

The power transformer is equipped with a large power transformer that does not vibrate even at the maximum continuous output at the rated load. It has a separate winding structure with the secondary side and left and right channels completely separated.
In addition, a 15000 μ Fx4 large-capacity type capacitor is used to provide a high power of 150W + 150W at ease.

Equipped with a high-precision meter that can directly read the peak output level in dB and wattage at 8 Ω load.
Since the scale is logarithmic compression type, it can be monitored from small output to large output without switching the range.

Equipped with an ASO-detection-type protection circuit that immediately limits the signal to a safe value when the output current or voltage exceeds the safe operating range, protecting the output transistor without compromising the faithful reproduction of the music signal.

Model Rating

Type	Stereo power amplifier
Rated output	150W + 150W (8 Ω) 190W + 190W (4 Ω)
Output bandwidth	5 Hz to 100,000 Hz
Total harmonic distortion factor	0.01% or Less (20 Hz ~ 20 kHz, 8 Ω Load)
Cross modulation distortion factor	0.01% or less
Frequency characteristic	(+ 0, -0.2 dB) : 20 Hz to 20 kHz (+ 0, -1dB) : DC ~ 100 kHz
Input Sensitivity / Impedance	1.5V/30k Ω
Damping factor	100 or More (8 Ω Load)
Residual noise	0.034 mv (IHF-A curve)
Power consumption	Maximum output : 850W Electrical Appliance and Material Control Law : 400W
Pwer	100 V, 50/60Hz
External dimensions	Width 416x Height 146x Depth 332 mm
Weight	22kg
Sold Separately	Cabinet WC-77 (Walnut Finish) : ¥ 8,000 WC-77N (Mahogany Finish) : ¥ 12500 Dedicated Rack Handle RHA-7 : ¥ 4,000 (1 set)