YAMAHA AX-1200
¥ 128,000 (around 1994)
Commentary
This pre-main amplifier was developed using Yamaha's original technology to ensure stable drive performance regardless of the type, size, or impedance variation of the speaker, regardless of source.
In order to obtain stable driving regardless of frequency changes, Yamaha's original linear damping circuit is mounted.
The power amplifier, CD-input 0 dB amplifier and 16 dB flat amplifier are each composed of discrete amplifiers with optimum gain according to the purpose to achieve high characteristics and high sound quality.
The power amplifier uses Yamaha's original HCA circuit that compensates for ideal class A operation in the full load and power range.
I of the transistorC-VBEBy utilizing the logarithmic characteristic of the characteristic as it is, we discovered that class A operation of hyperbolic conversion amplification (hyperbolic conversion amplification), which can obtain linear rigidity characteristic without cutting off in the whole power range, is possible, and we realized Yamaha's unique HCA circuit with a simple circuit configuration of two dual transistors without depending on idling current.
A pure direct switch is available for all inputs. When the switch is turned ON, it bypasses the subsonic filter and tone control and provides a simple signal path through the input selector and volume volume.
In addition, speakers A and B each use an independent gold-plated 2-contact relay to minimize the path from the output of the amplifier to the terminal. In addition, by using φ 1.6 mm wire for the output and power supply, impedance is reduced to achieve higher quality.
The structure is symmetrical from the power amplifier inlet to the output terminal, and the voltage amplifier stage and current amplifier stage are arranged separately to minimize interference.
In addition, the ground sensing circuit monitors the input and output grounds, and if there is a difference due to external noise, etc., it is canceled immediately before the power amplifier.
In order to completely eliminate vibration, we have adopted Yamaha's newly developed vibration isolation base, which suppresses and absorbs vibration generated from the inside of the amplifier such as the transformer and heat sink.
In addition, by attaching all parts to this vibration isolation base, the adverse effect of vibration on the music signal is completely eliminated, and the reproduction of purer sound is realized.
The power supply is equipped with a large power transformer (EI111x80, 420 va, equivalent to the AX 2000 a, and an aluminum electrolytic capacitor (22,000 μ Fx2) for audio equipment.
Equipped with MC/MM equalizer amplifier.
Four volumes are installed at the front and rear of a 16 dB discrete buffer amplifier to reduce the noise level at a small volume by up to 16 dB. This reduces the S/N in actual use.
The input selector is a rotary type that can be used for remote control.
It comes with an input selector and a remote control to control volume and muting.
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Model Rating
| Type | Pre-main amplifier |
| Rated Output (20 Hz ~ 20 kHz) | 185W + 185W (6 Ω, 0.003% strain) |
| Dynamic Power | 460W + 460W (2 Ω) 360W + 360W (4 Ω) 290W + 290W (6 Ω) |
| Input Sensitivity / Impedance | Phono MC : 160 μ V/220 Ω Phono MM : 2.5mV/47k Ω CD, etc. : 150mV/47k Ω Main in : 1V/47k Ω |
| Maximum Allowable Input (1 kHz, Distortion 0.01%) | MC:13.5mV MM:170mv |
| Frequency characteristic | Total Input : 20 Hz ~ 20 kHz ± 0.5 dB |
| Total harmonic distortion rate (20 Hz to 20 kHz) | 0.003% (MM → Rec out, 3 v) 0.007% (CD Others → SP out, 72.5W, 8 Ω) |
| Damping factor | 350 (20 Hz ~ 20 kHz, 8 Ω) |
| S/N ratio (IHF-A) | Phono MC : 68 dB (250 μ V) Phono MM:86dB(2.5mV) CD, etc. : 110 dB (Pure Direct SW on) |
| Residual Noise (IHF-A) | 35 μ V (Pure Direct SW on) |
| Tone control | Bass : ± 10 dB (20 Hz) Turnover frequency : 200 Hz, 400 Hz Treble : ± 10 dB (20 kHz) Turnover frequency : 2.5 kHz, 5 kHz |
| Subsonic filter | 15 Hz, -18dB/oct. |
| Maximum continuous loudness correction | -40dB (1 kHz, based on sound correction curve) |
| Pwer | AC100V 50/60Hz |
| Power consumption | 260W |
| External dimensions | Width 473x Height 171x Depth 448 mm |
| Weight | 20kg |
| Attachment | Wireless Remote Control |