The legendary Rangemaster effect. At the time, that is the end of the ’60s, the amplifiers are not prepared to distortion. I prefer to have a nice voice, faithfully reproduce the sound of the guitar. Of course, it was possible to overdrive when the guitar was full volume. If an external device, the sound midrange has been highlighted, they were given a musically useful sounds. At that same time, more “mid boost” existed. Among the most famous of all, to this day the “Dallas Rangemaster”. This is a very simple circuit using germanium transistor. The original device uses a OC44 transistor.