Description
Key Features
The TA-AX500’s headline engineering feature is its Audio Current Transfer circuit, in which the preamplifier’s output is converted to a current signal before being converted back to voltage by a linear gain-control attenuator, rather than being passed directly as a voltage signal between stages in the conventional manner. Sony’s rationale was that this approach renders the effects of switch and connector contact resistance, and the intrinsic impedance of interconnecting wiring, effectively negligible, while making the preamplifier’s output impedance appear almost infinite from the power amplifier’s perspective — in effect isolating the two stages electrically and allowing each to perform independently. The power amplifier section uses Sony’s Legato Linear circuit, a fixed-bias design intended to minimise switching and crossover distortion without resorting to sliding bias or variable supply-rail schemes, paired with wide-bandwidth, fast-response transistors operating in a cut-off range chosen specifically to avoid switching distortion at high frequencies. The volume control itself uses a linear gain-control attenuator matched to the current-transfer topology, said to offer a worthwhile signal-to-noise improvement over a conventional potentiometer.
On the front panel, a CD Direct button routes the CD input straight to the power amplifier stage, bypassing the function switching, tape monitor, subsonic filter, graphic equaliser loop, and tone control circuitry entirely for the most direct signal path available. The phono stage offers switchable equalisation for both moving magnet and moving coil cartridges, with a genuinely high-gain MC equalising amplifier fitted as standard rather than offered only via an outboard step-up, and there’s a subsonic filter to help control rumble and warp-induced low-frequency disturbance from vinyl replay. A dedicated graphic equaliser loop and two tape recorder loops (with tape copy 1↔2 facility) round out a flexible set of connections for a system built around multiple sources.
Technical Specifications
(Source: Sony service documentation, cross-referenced via HiFi Engine and Audio Database)
- Type: Integrated stereo amplifier with CD Direct function
- Circuit topology: Audio Current Transfer, Legato Linear power amplifier stage
- Rated power output: 80W + 80W (20Hz–20kHz, both channels driven, 0.008% THD, 8Ω); 100W + 100W (1kHz, 6Ω)
- Power bandwidth: 5Hz–50kHz (40W output, 0.02% THD, 8Ω)
- Damping factor: 50 (1kHz, 8Ω)
- Frequency response: Phono, RIAA ±0.2dB; line inputs, 5Hz–150kHz +0/–3dB
- Signal-to-noise ratio: Phono MM 86dB, Phono MC 75dB; line inputs 98dB
- Phono input sensitivity/impedance: MM 2.5mV/50kΩ; MC 170µV/100Ω
- Tone control: Bass ±10dB (60Hz, 300Hz turnover); Treble ±8dB (25kHz, 5kHz turnover), with tone defeat
- Subsonic filter: 15Hz or below, 6dB/octave
- Headphone output: 24mW/8Ω
- Power requirement (this example, UK model): 240V AC, 50/60Hz, 170W
- Dimensions: 430 x 130 x 365mm (W x H x D)
- Weight: 11kg
- Country of Manufacture: Japan
Important Owner’s Notes
This amplifier is now over 40 years old, and while fully tested and working correctly, buyers should bear in mind the usual considerations for equipment of this age, including the eventual need for servicing of switch contacts and potentiometers should any crackle or intermittency develop with continued use.
Why Buy From Us
With over 40 years of experience in the Hi-Fi industry, we are well placed to assess and test equipment of this type. Every item we list is fully inspected and tested before sale — this unit was checked by Andrew in our workshop.
When you buy from us you can expect:
- Full inspection and testing prior to listing — not simply a visual check
- A 3-month guarantee on every item we sell
- Transparent descriptions with no omissions
- Professional packaging to ensure safe delivery
- After-sales support available by phone or email should you have any questions
Summary
A genuinely excellent-condition example of the Sony TA-AX500, offering an unusually comprehensive specification for the period — including switchable MM/MC phono, graphic equaliser loop, subsonic filter, and CD Direct switching — built around Sony’s distinctive Audio Current Transfer and Legato Linear circuit designs. This is a single-unit listing. Please feel free to get in touch with any questions prior to purchase.
