COUNTERPOINT Solid-M1
¥ 265,000 (around 1994)
Commentary
This solid state series stereo power amplifier was developed using Counterpoint's unique hybrid technology to realize the potential of solid state elements.
In order to obtain good stereo separation, dual mono construction is carried out thoroughly. After the secondary winding of the power transformer, the rectifier diode and the filter condenser are separated into left and right channels and regulated independently. Each of them is equipped with a power supply dedicated to the voltage amplification stage.
The Solid-M1 amplifier circuit consists of three sections.
First, in the differential FET input stage with constant current cascode connection, stability is ensured by using a dual monolithic gain element in which two FETs are integrated, and linearity and wide-band characteristics are obtained. The subsequent voltage amplification stage consists of a pair of differential transistors and is controlled by a high-impedance current mirror load with cascode connection which is advantageous for high-band characteristics.
The output stage is class AB operation with the full complimentary service configuration of bipolar transistors. The output impedance is kept low to enable stable operation even under complicated loads. The bias current is set higher as it is closer to class A to stabilize the device.
The bias current can be switched between high and low and can be set up according to installation conditions.
In the Solid-M1, the amount of NFB, which is normally 60 to 70 dB, is reduced to less than 14 dB, which has almost no effect on sound quality. While achieving an excellent damping factor, the Solid-M1 ensures dynamic performance.
In addition, as a DC servo direct coupling, the capacitor is removed from the feedback loop, and high precision reproducibility, high resolution, and long-term operational stability are obtained in the entire playback band.
The DC servo system is also designed to eliminate the effect of DC component leakage, which is fatal to speakers.
The front panel is made of thick solid aluminum carefully made by the Counter Point Metal Shop to keep the internal temperature stable and prevent vibration from affecting the sound quality.
The rear panel uses a heat sink.
Model Rating
| Type | Stereo power amplifier |
| Rated output | 100W/ch (8 Ω) 170W/ch (4 Ω) |
| Input impedance | 100k Ω |
| Distortion factor | 0.2% (8 Ω, 1 kHz, 100W) |
| Frequency characteristic | 1 Hz to 150 kHz |
| Signal-to-noise ratio | 93 dB (10 Hz to 20 kHz) |
| Damping factor | 75(1kHz) |
| Gain | 32dB |
| DC Offset | 10 mv or less |
| Signal polarity | Non-inversion |
| Pwer | 100 VAC, 50Hz/60Hz |
| Power consumption | 50W (idle) |
| External dimensions | Width 483x Height 120x Depth 360 mm (max) |
| Weight | 12kg |
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