Description
The Stereo 70 is built around a quasi-complementary output stage employing the venerable 2N3055 transistors, a topology that was something of a standard in quality British amplifiers of the late 1960s. The amplifier is capacitor-coupled to the loudspeakers, which was conventional for the era and contributes to the amp’s characteristic warm, midrange-focused presentation. A fixed subsonic filter at 17Hz with an 18dB-per-octave slope is built in to protect against turntable rumble and acoustic feedback, whilst a switchable treble filter at 6kHz (12dB/octave) offers additional taming of harsh recordings.
The input complement is generous for a compact integrated amplifier of this period. Two phono inputs are provided: Pickup 1 is a standard moving-magnet input with 47kΩ impedance and 2mV sensitivity, whilst Pickup 2 offers selectable sensitivity via rear-panel HI/LO switches to accommodate higher-output moving-magnet, moving-coil, or ceramic cartridges. Two tuner inputs are also fitted, again with gain switching on the rear panel, along with a tape monitor loop and a front-panel DIN socket for portable tape recorders. A mono switch allows summing to both channels from either left or right input, which is useful for mono record playback.
Tone controls offer ±16dB at 50Hz and ±14dB at 14kHz, with a balance control to compensate for loudspeaker sensitivity differences. The amplifier can drive two pairs of loudspeakers simultaneously via separate Main and Remote switching, with DIN-type speaker connectors on the rear panel. Loudspeakers of 8–15 ohms are recommended, though 4–5 ohm models may be used on the Main outputs provided no second pair is connected. A headphone socket is fitted on the front panel. The rear panel also features a multi-voltage selector (110/117/130/210/230/250V) and AC outlet sockets for powering ancillary equipment.
Technical Specifications
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Type: Integrated Stereo Amplifier
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Power Output: 35W RMS per channel into 8Ω; 28W RMS per channel into 15Ω (both channels driven, 1kHz)
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Total Harmonic Distortion: 0.1% at all power levels up to 25W RMS per channel
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Intermodulation Distortion: Less than 0.5% at 35W into 8Ω; less than 0.3% at 28W into 15Ω
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Frequency Response: 30Hz – 20kHz (±1dB)
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Damping Factor: 20 (8Ω); 40 (15Ω) at 1kHz
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Input Sensitivity & Impedance:
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Pickup 1 (RIAA): 2mV / 47kΩ
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Pickup 2 (RIAA): 10mV (HI) / 30mV (LO); 33kΩ (HI) / 100kΩ (LO)
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Tuner 1/Mic: 25mV / 47kΩ
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Tuner 2: 60mV (HI) / 250mV (LO); 50kΩ
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Replay/Tape Monitor: 400mV / 47kΩ (monitor out) / 20kΩ (monitor in)
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Hum & Noise: 66dB below 30W (Tuner/Replay); 56dB below 30W (other inputs)
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Crosstalk: -50dB up to 1kHz; -30dB at 10kHz
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Tone Control Range: ±16dB at 50Hz; ±14dB at 14kHz
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Filters: Subsonic 17Hz (18dB/octave, fixed); Treble 6kHz (12dB/octave, switchable)
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Loudspeaker Impedance: 8–15Ω (4–5Ω permitted on Main outputs only)
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Power Requirement: 110/117/130/210/230/250V AC, 40–60Hz, 150VA
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AC Outlets: 100W maximum
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Year of Production: c. 1968 – 1971
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Country of Origin: England (Made in London, England — as per rear panel label)
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Serial Number: Z 109997
Important Owner’s Notes
The Stereo 70 is now over 50 years old and its internal electrolytic capacitors are original. While the amplifier is currently working correctly, a precautionary service — including inspection and replacement of the main electrolytic capacitors — is advisable as part of longer-term ownership, and is something we would be happy to discuss prior to purchase.
The loudspeaker connectors on this amplifier are of the DIN type, which was standard for British and European equipment of this era. If your loudspeaker cables terminate in banana plugs or spades, suitable DIN adapters or replacement cables will be required. Please note also that one side of the loudspeaker wiring is connected to the chassis, so no additional earthing should be made to the loudspeaker cables.
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:
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Full inspection and testing prior to listing — not simply a visual check
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A 3-month guarantee on every item we sell
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Transparent descriptions with no omissions
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Professional packaging to ensure safe delivery
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After-sales support available by phone or email should you have any questions
Summary
The Leak Stereo 70 is a well-regarded British integrated amplifier from the late 1960s, offering a warm and musical presentation via its quasi-complementary 2N3055 output stage. This chassis-version example is in good condition for its age and represents an accessible entry into classic British transistor amplification. No wood case is included. This is a single-unit listing. Please feel free to get in touch with any questions prior to purchase.
