Troughline

About the Troughline

The Leak Troughline Stereo is a valve-based FM tuner featuring a built-in stereo decoder using three AF126 transistors. It covers the FM broadcast band from 88 to 108 MHz with a superheterodyne design and a 12.5 MHz intermediate frequency. The tuner is known for its outstanding audio quality, surpassing many transistor tuners of its era. It uses a unique tapped transmission line for tuning stability and includes valves such as ECC88, ECC85, 2x ECF80, EF80, EZ80, and EM84. The stereo decoder has three potentiometers for input gain, oscillator lock, and stereo separation, with the latter two factory set. The tuner outputs approximately 150 mV per channel at 75 kHz deviation, designed to drive high-impedance inputs (47k to 100k ohms). It features a cathode follower output for mono and high impedance stereo outputs. The unit measures approximately 292 x 108 x 210 mm and weighs about 5.8 kg. It has a distinctive front panel with rotary knobs for tuning and mode selection, a tuning dial, and slide switches. The tuner is highly regarded for its low distortion (quoted at 0.1%) and stable performance after warm-up, with a tuning indicator (EM84) and a robust mechanical design.