Technics SU-V6
¥ 59,800 (around 1979)
Commentary
Integrated DC pre-main amplifier with new class A system using Technics original synchronized bias circuit.
In the new class A amplification method, a constant bias current is applied to the - side output stage that stops amplifying when the + side signal is received, and to the + side output stage for the - side signal, a constant bias current is applied to the + side output stage. The output stage is always active regardless of the presence or absence of the signal, and the transistor is non-cutoff to eliminate switching distortion.
In addition, since the signal path and bias current are independent, the output transistor always keeps an appropriate operating point, and the high-speed response diode that switches the waveform has a composite transfer characteristic close to the ideal square characteristic, eliminating crossover distortion.
A straight-DC method is adopted in which the DC amplifier directly amplifies the signal after the high-level input. This realizes faithful waveform transmission characteristics up to the DC range and further flattens amplitude and phase frequency characteristics in the audible frequency range.
In the first stage of the main amplifier, a single-chip dual FET with excellent temperature characteristics is adopted.
In normal operation at -10 ℃ to + 50 ℃, the DC drift is less than ± 10 mv, which is about 1/5 of the conventional level, and is kept at the minimum level.
A low-noise dual-FET differential amplifier is used in the first stage of the phono equalizer circuit.
By adopting FET, both MM and MC are ICL equalizers that eliminate the input capacitor. Therefore, when the operation mode is set to straight DC, a simple circuit configuration with only one coupling capacitor (output capacitor of the equalizer) between the phono input and the speaker terminal is realized.
A high-gain IC (100 dB or more) is used in the next stage of the phono equalizer. Together with the adoption of an extremely low-noise FET, the MM right / left MC gain switching system is realized. This enables direct use of the MC cartridge.
It uses a concentrated power block that suppresses distortion caused by electromagnetic induction.
In this block structure, the power supply and output transistor are integrated and connected at the shortest distance to minimize distortion in the high-frequency range caused by electromagnetic waves.
Two independent left and right power supplies are used, in which rectification and smoothing circuits are independent for both left and right channels.
The power transformer employs a high-performance transformer in which the coil is floated in a special resin and housed in a shield case, reducing harmful mechanical vibration and providing a high shielding effect.
An FET is used for the load of the error detection circuit of the constant voltage power supply, and a stable voltage with a high ripple (AC component) removal rate that causes harmful hum noise is supplied to the voltage amplification stage up to the first stage of the main amplifier.
It is equipped with a load detection type protection circuit that suppresses the current flowing to the power IC when the load impedance is 2.2 Ω or less. In addition, it is equipped with a DC detection type protection circuit that operates a relay to disconnect the speaker when the DC component of ± 3 v or more is emitted.
Both circuits automatically return to normal operation when the cause is cleared.
Remote action switches are used for the Rec selector, Input selector, and Phono selector to minimize wiring and suppress characteristic degradation.
The tone control is a type that is deviated at the midpoint.
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Model Rating
| Type | Integrated DC amplifier |
| <Overall characteristics of Tuner, Aux → SP out> | |
| Effective output (20 Hz to 20 kHz) | 70W + 70W (8 Ω, 0.007%) |
| Total harmonic distortion factor | 0.005% (Rated Output -3dB, 20 hz to 20 khz) |
| Power Bandwidth (THD 0.02%) | 5 Hz to 100 kHz |
| Frequency Response (Straight DC) | 20 Hz ~ 20 kHz + 0 -0.1 dB DC ~ 150 khz + 0 -3dB |
| SN ratio (IHF-A, straight DC) | 106dB |
| Residual Noise (straight DC) | 450 μ V |
| Damping factor (8 Ω) | 60 |
| Load impedance | Main or remote : 4 Ω ~ 16 Ω Main and remote : 8 Ω ~ 16 Ω |
| <Other characteristics> | |
| Input Sensitivity / Impedance | Phono MM : 2.5mV/47k Ω Phono MC : 170 μ V/47 Ω Tuner, Aux, Tape : 150mV/47k Ω |
| Signal-to-noise ratio (IHF-A) | MM:86dB MC : 68 dB (250 μ V input) |
| Frequency characteristic | 20 Hz to 20 kHz, RIAA ± 0.5 dB |
| Tone control | Bass : ± 10 dB (50 Hz) Treble : ± 10 dB (20 kHz) |
| Subsonic filter | 20 Hz, -12dB/oct. |
| High filter | 7 kHz, -6dB/oct. |
| Loudness control | + 7 dB (50 Hz, Volume -30dB) |
| <General> | |
| Pwer | 100 VAC, 50Hz/60Hz |
| Power consumption | 182W |
| External dimensions | Width 430x Height 153x Depth 351 mm |
| Weight | 12.3kg |