But the thing is that most amp manuals are useless. But not Mesa's. If you have Mesa gear, everything you want to know is probably in the manual. Ej: "My Triaxis is broken!!! Presence doesn't work on Rectifier mode!!!" The manual: 3. The PRESENCE control is too far back in the circuit to have a major effect on the timbre of LEAD 1 Red. Its effect is almost imperceptible, apart from very high levels or very deep settings. This is completely normal and shouldn't worry you. We think TREBLE and MIDDLE offer enough space for tone shaping. The PRESENCE controls in circuits of a similar nature are always located in the output stage of the amplifier. Use PRESENCE in LEAD 1 Red only for fine adjustment control of the attack and sound, and in the remaining seven modes as the normal tone control element that it was intended.