Epiphone Valve Junior has become very popular to modify because of its basic design. There are many websites, kits, and forums dedicated to this purpose, including the Epiphone official amps and accessories forum. Some sites offer kits to match the gain characteristics of Marshall, Fender and Vox amplifiers. These kits often do not include a bridge rectifier to convert the version 1 AC filament supply voltage to DC, instead they suggest twisting the AC leads together to cancel the generated electromagnetic fields, a technique used in twisted-pair Ethernet cable to eliminate crosstalk. Valve Junior Hot Rod A somewhat limited edition of the Valve Junior head was produced by Epiphone, dubbed the Valve Junior Hot Rod. It was released as a response to the extensive number of modifications that were being applied to the regular Valve Junior. The circuitry was altered to include a second 12AX7 preamp tube, a gain control, and a spring reverb in addition to the single volume control, as well as a standby switch to preserve tube life. Thanks to a dual function jack on the amp's rear panel, the Hot Rod can also be used as a standalone reverb unit to be used in conjunction with another amplifier's input or effects loop. In this function, the gain knob becomes the unit's dwell control, the volume knob retains its level function, and the reverb knob becomes the mixture control. When used as a reverb unit, the Hot Rod does not need to have a speaker connected to its output jacks because an internal "dummy load" activates automatically when the Reverb output jack is used. Serial Numbers The first 4 digits of the serial number are the date code ( = month, = year). Version 2 Valve Juniors have date codes starting at "" January 2006 up to June 2007 when version 3 was released. See also Epiphone Gibson External links Epiphone Valve Junior Official Page Epiphone Valve Junior Combo Review Instrument amplifiers Valve amplifiers