TRAFOMATIC AUDIO TARA 30A PREAMPLIFIER February 9, 2020 Matej Isak Trafomatic Audio Tara 30A Preamplifier. This custom made, cost no object tube preamplifier designed by Saša Čokić is fully balanced, frequency range from 10Hz ( -1dB ) up to 200Khz ( -3dB) and with 14dB gain.