Do It Yourself DIY: EL34 Twin Coupled Stereo Tube Amplifier By stellartv on June 23, 2014June 23, 2014 Feature from October 1960 issue of Radio-Electronics magazine. Posted in: 12AU7, 12AX7, antique electronics, audiophile, diy, EL34, hi fi, push-pull, tube amplifier, tube audio, tube stereo, twin coupled, vacuum tube, vintage audio, vintage electronics No comments