Zero Hysteresis Transformerless tube amplification In this edit on 19 Mar 2014 Drmies removed this text Zero Hysteresis Transformerless tube amplification In 2009 Milbert introduced a tube guitar amplifier which eliminates the traditional audio output transformer and all traditional power supply magnetics by using Berning s patented ZOTL circuit to almost perfectly and bi directionally mate power tubes in any combinations and speaker load resulting in transfer characteristics being accurately and fully conveyed between tubes and speaker s and asserted Zero Hysteresis Transformerless tube amplification no verification no suggestion that this esoteric brand needs special mention in the general article only differencetransformerless It should be pointed out that there are many advantages offered by the patented ZOTL Technology including ultra light weight due to no audio output or bulky power supply magnetics automatic standby capability ability to use any common vacuum tubes in any combinations and have them automatically biased freedom from 60 Hz powerline hum ability to automatically drive any practical output impedance s and also total opens and dead shorts even at full power without destruction of non existent traditional audio output transformer due to high voltage flyback arcing and consequent insulation breakdown and an unequaled purity of tube tone due to the complete elimination of all otherwise inescapable audible parasitics