Technics SU-A700 (1993–1999)
At 6.4kg, it sits on the shelf solid and no-nonsense.
Overview
This is the Technics SU-A700, a mid-tier integrated amplifier from the mid-90s. Reportedly built in Japan during the 1990s, it was made for function, not fanfare. Owners report it was priced around ¥49,800 in 1994. That put it in serious-component territory, but not flagship territory. It's a stereo integrated amplifier with a full set of analog inputs, including a dedicated MM phono stage, so it works as a hub for turntables, CD players, and cassette decks of the era.
The build is the first thing you notice. The 430mm-wide chassis is dense, and its 6.4kg mass comes partly from a newly developed R-core power transformer that Technics claimed minimized magnetic flux leakage. That transformer feeds a circuit Technics called MOS Class AA. A power MOS-FET handles voltage control in class A, and a bipolar transistor handles current delivery. The idea was to get the linearity of MOS-FETs at low output and the current muscle of bipolar devices when demand spikes. Owners debate whether that is audible or just clever engineering. The specs back up the intent: approximately 40W + 40W into 8Ω with a rated distortion factor of around 0.01% across the full 20Hz - 20kHz band.
The front panel is clean, almost austere. No flashy meters, no VU displays - just a motor-driven volume knob that responds to the included wireless remote. The remote is also a system controller for basic operations on compatible Technics CD players, tuners, and cassette decks. Input selection, source switching, and speaker A/B toggling are all handled by relays with gold-plated contacts, a detail Technics emphasized for long-term reliability. The back panel has two sets of speaker terminals that accept banana plugs. Both A and B outputs can run at the same time when driving 8Ω loads, which is handy for multi-room use.
Despite its modest size, the SU-A700 borrows design elements from higher-end models. The multi-layer THCB (Tough High-rigidity Chassis Base) structure uses steel and hard rubber layers to suppress vibration, a technique refined in Technics' turntable division. Inside, a high-quality X-Pro power capacitor is used. Later variants like the MK3 reportedly upgraded to Master Series capacitors, but that is not confirmed for the base model. The frequency response runs from 3Hz to 80kHz, far beyond the audible range, which suggests a design tuned for transient accuracy rather than just paper specs.
User reports are sparse but generally positive. One owner noted preferring it over the non-remote A600 version after reading a review in either *Audiophile* or *Hi-Fi News*. Another, writing from memory two decades later, recalled saving hard to afford it as part of a separates stack. There's no widespread acclaim, no cult following, and no chorus of complaints either.
Specifications
| Manufacturer | Technics |
| Product type | Integrated amplifier |
| Rated output | 40W + 40W (20 Hz to 20 kHz, 0.01%, 8 Ω) |
| Rated distortion factor | 0.01% (20 Hz ~ 20 kHz, Rated Output, 8 Ω) |
| Total harmonic distortion factor | 0.01% (20 Hz to 20 kHz, Rated Output -3dB, 8 Ω) * Total sum up to 10th harmonic |
| Damping factor | 60 (8 Ω) |
| Load impedance | 4 ~ 16 Ω (A, B), 8 ~ 16 Ω (A + B) |
| Frequency characteristic | 3 Hz to 80 kHz (+ 0 dB, -3dB) |
| Equalizer deviation | 30 Hz to 15 kHz (+ 1 dB, -1dB) |
| Input Sensitivity / Impedance Tuner, CD, aux, tape1, tape2 | 150mV/22k Ω |
| Input Sensitivity / Impedance Phono MM | 2.5mV/47k Ω |
| Tone control characteristics | ± 10 dB : 50 Hz, ± 10 dB : 20 kHz |
| Signal-to-noise ratio Tuner, CD, aux, tape1, tape2 | 83 dB (EIAJ), 99 dB (IHF' 66) |
| Signal-to-noise ratio phono MM | 78dB(EIAJ) |
| Power | 100 VAC, 50Hz/60Hz |
| Power consumption | 140W |
| External dimensions | Width 430x Height 125x Depth 318 mm |
| Weight | 6.4kg |
| Attachment | Wireless Remote Control |
Key Features
MOS Class AA Circuit with Power MOS-FET
The SU-A700's defining technical trait is its MOS Class AA output stage, a hybrid design developed by Technics. A power MOS-FET operates in class A as the voltage control amplifier, prized for its linearity at low signal levels. A bipolar transistor handles current amplification and takes over when higher output demands heavy current delivery. The goal was to combine the benefits of class A operation - smoothness, low crossover distortion - with the efficiency and drive capability of bipolar output stages under load. Technics developed its own power MOS-FETs to realize the circuit.
R-Core Power Transformer
The power supply is built around a newly developed R-core transformer, tightly wound around a circular core to produce a uniform magnetic flux. According to Technics, this design minimizes magnetic flux leakage, which reduces the risk of electromagnetic interference with sensitive audio circuitry. R-core transformers are known for their efficiency and low mechanical hum, and they are a step up from the more common EI-core types found in budget gear.
Multi-Layer Vibration Isolation Structure Using THCB
The chassis uses a multi-layer T. H. C. B. (Tough High-rigidity Chassis Base) construction. Steel and hard rubber are layered to dampen mechanical vibration. The approach was refined in Technics' analog playback division and adapted here to prevent microphonic effects and resonance from degrading signal purity. It makes a rigid, damped platform that isolates sensitive components from both external and internal sources of vibration.
Input/Output Switching via Gold-Plated Contact Relay
Signal routing is handled by gold-plated contact relays that connect inputs and outputs directly to their terminals. Gold plating resists oxidation, which keeps conductivity consistent over time. The relay-based switching also avoids the wear and contact noise of mechanical potentiometers or selector switches. Technics emphasized this as a reliability feature, with clean, stable connections across thousands of operations.
Banana Plug-Compatible Speaker Terminals with A/B Output
The rear panel has speaker terminals for two sets of speakers (A and B), both compatible with banana plugs for secure, low-resistance connections. The amplifier allows both speaker pairs to run at once when each presents an 8Ω load, which is useful for driving speakers in multiple rooms. The 4-16Ω impedance tolerance per channel lets the SU-A700 work with a wide range of speaker systems.
System Remote Controller for Technics Components
The SU-A700 ships with a wireless remote control that operates basic functions - play, stop, power, input select - on compatible Technics CD players, tuners, and cassette decks. It was a convenience feature meant to simplify multi-component setups. The volume control itself is motor-driven, so the remote can make smooth, precise adjustments without the wear of direct-coupled potentiometers.
High-Quality X-Pro Power Capacitor
The power supply uses a high-quality X-Pro electrolytic capacitor, selected for stable performance and longevity. It is not as exotic as the "Bamboo Mixing" capacitors sometimes mentioned in enthusiast circles (a term not confirmed in the official specs), but the X-Pro unit was part of Technics' effort to use premium components in critical signal and power paths. Later variants like the MK3 are reported to have used Master Series capacitors, but that upgrade is not documented for the base SU-A700 model.
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