Technics SU-V9

Commentary

An integrated DC amplifier equipped with a new class A method and linear feedback circuit as a top-of-the-line model of the new generation V series integrated amplifier.

The power amplifier class A system has been adopted for the power amplifier section, and low distortion and high power have been obtained by synchronous bias circuit, linear feedback circuit and concentrated power block.
The basic circuit configuration is a push-pull complimentary service configuration for all stages from the first stage FET differential amplification, current mirror load and bootstrap configuration to the third stage Darlington. Bare strain is reduced thoroughly.
The power transistor uses a large power type of Pc200W to achieve high power and low distortion stable operation.

The linear feedback circuit is a circuit that returns to the ideal of NFB theory and assumes that the naked amplification degree of the amplifier is ∞. By forming an independent feedback circuit that enables the naked amplification degree of the amplifier to be ∞ in the NFB loop by making the best of the multiple feedback circuit technology, the theoretical value of distortion = 0, pure gain without the influence of elements or power supply, and speaker drive without the influence of back electromotive force or wire.
The linear feedback operates over the entire amplification band, and at the lower limit of the range of audibility, it is almost infinite, and even at the upper limit of 20 kHz, it is 40 dB or more, showing an excellent distortion improvement effect.

In the synchronous bias circuit, a constant bias is supplied in synchronization with the rest cycle of the output transistor, which normally stops alternately at class B and class AB. By keeping the output stage in the active state at all times, switching distortion caused by the rest is eliminated. In addition, the signal path and bias current path are independent, so crossover distortion is eliminated.

The concentrated power block that integrates the output stage and power supply prevents the adverse effects of electromagnetic fields from the root. This method is positive and highly effective in preventing problematic electromagnetic waves from escaping. Therefore, magnetic materials with high shielding effect can be used for chassis and cover, etc., and external induction is suppressed, which is an advantage of actual installation.

It is equipped with a three layer protection circuit. It is equipped with a heat detection protection circuit in addition to a protection circuit using a relay to protect the amplifier from a short circuit of the speaker terminal, etc. and the speaker from an unexpected abnormal operation of the amplifier. When the temperature inside the amplifier rises abnormally, the voltage of the servo power supply is automatically lowered, leading to thermally stable operation.

Automatic load detection servo power supply is used for the power supply section.
This servo power supply greatly improves the response of power supply by controlling the conduction angle simultaneously with rectification by four SCRs combined in a bridge type with a voltage detection circuit. Voltage fluctuations due to primary side fluctuations and large current consumption of the output stage are eliminated, and stable voltage is supplied to all stages including the output stage.
In addition, it has achieved a low impedance of 1 / 10 that of conventional products, and a high regulation equivalent to a built-in power supply of 10 times the size.
In addition, this servo power supply is equipped with load impedance detection and tap switching circuit that detects the composite impedance of the speaker connected to the speaker terminal immediately after the power supply is turned on. High-voltage or low-voltage taps of the transformer winding are automatically selected. The same rated output is guaranteed regardless of whether the impedance of the speaker is 8 Ω or 4 Ω.

A linear feedback circuit unique to Technics is also incorporated into the phono equalizer circuit.
This makes it possible to apply a large amount of NFB over the entire range of the phono equalizer circuit, which tends to lack NF in the low frequency range, and realizes an excellent low distortion factor.
In addition, a differential amplifier using a low-noise FET in parallel is arranged at the first stage of the phono equalizer, and high gain amplification is performed by cascade connection and current mirror load. Then, high-performance ICs are used in the next stage and thereafter to obtain low noise.

Since both MM and MC are ICL equalizers that have eliminated the input capacitor, only one coupling capacitor is passed through during straight DG operation.
The high-gain input is amplified directly to the speaker terminal by a high-gain DC amplifier, enabling more faithful waveform transmission.

The selector switches for Phono, Input and Rec out are remote action switches.

With the Super Base Control that boosts only the very low range, and with a steep rise of 12dB/oct. and a shelving tone with a boost of up to 10 dB, the speaker's frequency response can be extended to the low range by approximately one octave.

Phono Input 1 is equipped with four input sensitivity switches, one mV / 2.5 mv and one 100 μ V/250 μ V, in addition to MM / MC switching. Input impedance is set to 47k Ω for MM and 100 Ω / 220 Ω for MC.

Model Rating

Type	Integrated DC amplifier
<Overall characteristics of Tuner, Aux → SP out>
Effective output (20 Hz to 20 kHz)	120W + 120W (4 Ω, 0.007%) 120W + 120W (8 Ω, 0.003%)
Total harmonic distortion factor	0.003% (Rated Output -3dB, 20 hz to 20 khz)
Power Bandwidth (THD 0.02%)	5 Hz to 100 kHz
TIM	Unmeasurable
Residual Noise (straight DC)	0.7mV
Damping factor (8 Ω)	80
Load impedance	Main or remote : 4 Ω ~ 16 Ω Main and remote : 8 Ω ~ 16 Ω
<Other characteristics>
Input Sensitivity / Impedance	Phono MM : 1.0 mV, 2.5mV/47k Ω Phono MC : 100 μ V/100 Ω, 250 μ V/220 Ω Tuner, Aux, Tape : 150mV/33k Ω
Phono maximum allowable input (1 kHz, RMS, THD 0.01%)	MM:170mV(2.5mV) MC : 17 mv (250 μ V)
Total harmonic distortion factor	Phono MM → Rec out : 0.0005% (1 kHz, output 5 V)
Frequency characteristic	Tuner, Aux, Tape : 20 Hz to 20 kHz + 0 -0.2 dB 0.5 Hz ~ 170 kHz + 0 -3dB
Signal-to-noise ratio	Phono MM : 88 dB (2.5 mV input) Phono MC : 71 dB (250 μ V input) Tuner, AuX, Tape : 103 dB
Tone control	Super Bass : -0dB to + 10 dB (30 Hz) Bass : ± 7 dB (100 Hz) Treble : ± 10 dB (20 kHz)
Turnover frequency	Super Bass : 75 Hz, 150 Hz (12dB/oct.) Bass:500Hz Treble:2kHz
Filter	High : 7 kHz, -6dB/oct. Subsonic : 20 Hz, -12dB/oct.
Loudness control	7 dB (50 Hz, Volume-30dB)
Output voltage of preamplifier section (Rec out)	150mV
<General>
Pwer	100 VAC, 50Hz/60Hz
Power consumption	205W
External dimensions	Width 430x Height 120x Depth 350 mm
Weight	14.7kg