TRIO 700C
¥ 220,000 (around 1974)
Commentary
Supreme series control amplifier.
The 700C is designed to improve the sound quality by enhancing the bare characteristics and applying NFB shallowly.
In addition, all circuits are connected directly to two power supplies, eliminating AC-DC and DC-DC interaction between circuits.
The equalizer section uses a first stage PNP differential amplifier circuit.
It is a differential amplifier circuit loaded with a high voltage of ± 50 v with 5 stages of direct connection. It achieves a maximum output of 30 v and secures a wide dynamic range. In addition, the DC operating point is stabilized by using differential and direct connection circuits.
Various characteristics such as f-characteristics, impedance, and amplification are improved by stabilizing with buffer stage.
We also stabilize the RIAA curve by taking a large naked gain so that we need only a shallow NFB.
The main volume consists of a 2-dB-step attenuator and a 15-dB-step attenuator. These two attenuators enable accurate 2-dB-step linear control over a range of 60 dB.
A constant voltage power supply is used for the power supply part to eliminate the influence of AC line voltage, etc.
In addition, it is equipped with a power rush prevention circuit and a muting device for preventing power ON shock.
The built-in Darlington A-class microphone amplifier is directly connected to the microphone, and the sound quality is improved by separating it from the equalizer.
In addition to the normal rotary selector, it is equipped with an AUX/Tuner one touch switching function using a lever switch.
Equipped with Phono impedance switching function of 50k Ω ・ 30k Ω ・ 600 Ω.
Equipped with a 7 khz and 12 khz switchable high filter.
Equipped with a tape monitor switch and loudness control.
The low filter is an active filter with a Darlington circuit and operates at 18 Hz and 36 Hz respectively at 12dB/oct.
Can also be used as a subsonic filter.
The tone control is a differential type and uses a CR switching circuit to eliminate waviness.
The basic amplifier circuit is 100Hz/10kHz (50Hz/20kHz) with 2 dB step change, and Bass/Treble two step switchover type.
When the switchover switch is turned off or the control knob is set to 0, the amplifier is a complete flat amplifier.
The headphone circuit uses a direct connection Darlington class A circuit.
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Model Rating
| Type | Control amplifier | ||
| Maximum output voltage (1 kHz, 50k Ω load) | 8Vrms | ||
| Reference rated output voltage | 1.5Vrms | ||
| Total harmonic distortion factor (1.5 V output, 50k Ω load) | 0.04% | ||
| Cross modulation distortion factor | 0.04% | ||
| Input sensitivity (at 1.5 V output) | Phono1, 2 : 1.5 mV Tuner:150mV Aux1, 2, 3 : 150 mv Tape play:150mV |
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| Signal-to-noise ratio | Phono1, 2 : 70 dB for 5 mV input Tuner : 85 dB (for 150 mV input) Aux1, 2, 3 : 85 dB for 150 mV input Tape play : 85 dB for 150 mV input |
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| Input impedance | Phono1, 2 : 50k Ω, 30k Ω, 600 Ω switching Tuner : 150k Ω Aux1, 2, 3 : 150k Ω Tape play : 150k Ω |
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| Output impedance | Tape rec (pin) : 4.7k Ω Tape rec (din) : 80k Ω Output : 400 Ω |
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| Maximum Input Voltage (Phono, 1 kHz) | 200mVrms | ||
| Frequency characteristic | Phono1, 2 (RIAA deviation) + / - 0.3 dB Tuner : 20 hz to 20 khz + 0 to 0.3 db Aux1, 2, 3 : 20 Hz to 20 kHz + 0 -0.3 dB Tape play : 20 Hz ~ 20 kHz + 0 -0.3 dB |
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| Tone control |
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| Low filter | Fc : 18 Hz, 36 Hz switching 12dB/oct |
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| High filter | Fc : 7 kHz, 12 kHz switching 6dB/oct |
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| Loudness control (Vol-30dB) |
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| Headphone out | 20mW/8 Ω | ||
| AC outlet | Switched : 2 lines Unswitched : 1 line |
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| Pwer | 100 VAC, 50Hz/60Hz | ||
| Power consumption (Electrical Appliance and Material Control Law) | 10W | ||
| External dimensions | Width 472x Height 177x Depth 318 mm (Including Case) | ||
| Weight | 9.5kg |
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