Leak TL50 Plus
A mono valve amplifier delivering 50 watts using KT88 tubes, produced from the late 1950s onward.
Overview
The Leak TL50 Plus is a mono power amplifier built by H.J. Leak & Co. Ltd., part of the brand’s “TL” series—named for its Triple Loop feedback design. It was referenced in High Fidelity magazine as early as October 1957 and remained in use into the late 1960s. Designed around the high-output KT88 beam tetrode tube, the amplifier can also operate with 6550 tubes. It was available in configurations with standard 4, 8, and 16 ohm output transformers, as well as a 100-volt line version for commercial installations.
Specifications
| Power output | 50 watts into 8Ω (mono) |
| Power tubes | Dual KT88 per channel (push-pull) |
| Compatible tubes | KT88 or 6550 |
| Output impedance options | 4, 8, 16 ohms or 100v line transformer |
Market
The Leak TL50 Plus is considered a rare vintage amplifier. A pair was listed for $2,650 in November 2019 (USAudioMart), AUD $8,250 in July 2022 (AussieAudioMart, including preamps), and €1,600 in April 2026 (HiFiShark). Units are sometimes offered "for spares or repairs," indicating potential need for restoration. Reproduction decals are available, reflecting ongoing collector interest.
eBay Listings
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