Dale Sherlock is a legendary figure in Australian amp building and the Fat Head is an icon – albeit a little-known-outside-of-Oz one. Sherlock’s popular mods and MIDI upgrades are killer ways to add extra functionality to an amp, but part of the charm of the Fat Head is that much of this utility, experience and knowledge is built right into the amp.
So what are we looking at here? Well the Fat Head is a four-channel, 50/100 watt monster which sends your sound on an all-analog journey through six tube stages for the two high-gin channels, four for the Edge channel and three for the clean, on through two or four power tubes, depending on mode. Those tubes can be 6L6 or EL34, or a pair of each – actually any octal-based power tube, for that matter.
The four channels are Clean, Edge, Rhythm and Lead, with Clean and Edge sharing one set of Bass, Mid and Treble controls and Rhythm and Lead sharing the other set (along with a Mid Scoop button). There are independent Gain and Volume controls for each channel, as well as a Bright switch for the Clean channel, plus three-way Tone switch and Gain button on the others. Front-panel channel switching is afforded via pushbuttons next to each of the Volume controls. Then there are two selectable Master Volume controls, two selectable Presence controls. and two Depth switches. The effects loop has adjustable Send and Return levels as well as a Series/Parallel switch and it can be selected for each channel via a front panel button. There’s also a Program button for saving your changes, and of course the standard Power and Standby switches.
Aside from the effects loop, MIDI In and Thru jacks, speaker jacks with 4/8/16 ohm impedance switch and effects loop, the back panel also features an additional input jack (especially handy for those who prefer to rack their heads), a Slave output with level control, and Sherlock’s Tube Management System (T.M.S). Part of the genius of the Fat Head is the way the T.M.S. handles power. Thanks to the BIAS REF. pots on the back, you can control the class of operation from Class AB to more Class A or even fully adjustable Simulclass, with any two tubes running Class AB and the others running Class A. Sherlock prefers JJ12AX7s for the preamp tubes and Svetlana winged C or JJ 6L6s and EL34s in the power stage.