The Fender Custom Vibrolux Reverb modified here is a re-issue built in 1993.Its main problem is an annoying amount of background hiss due to its feature of having reverb on both channels . The main circuit board used in the Vibrolux is the same as used in the better sounding '63 Vibroverb re-issue.So adding a few components and altering wiring to modify the preamp stage to a Vibroverb preamp will eliminate the reverb off the normal channel and thus remove a fair amount of hiss..The reverb on the Vibrolux is also much more filtered out than on a Vibroverb due to the coupling cap in its recovery stage.Changing this cap (C16) to a .0033 siver mica cap makes the reverb come alive.

Also the Vibrolux has no negative feedback.The Vibroverb has a NFB loop.Negative feedback loops negate hiss and unwanted noise. This is achieved by running a wire from the + speaker out back to the control grid of the phase invertor.

Other mods include placing a 100pf shunting cap across the 12ax7 phase invertor plates which reduces parasitics which are inherent with a circuit board. Also removal of the surge protection diodes across the 6L6's which sometimes causes the amp to blow fuses when switching from stand-by to on ,and also seems to drain off some of the high frequencies.

Hardwiring and thus eliminating the small copper push on connectors ( pic5 )which are commonplace in all recently produced Fender amps will eradicte alot of intermittant noises . The currently produced Mexican amps are prone to these problems within about 2-3 years of leaving the factory.

Other suggestions for upgrading your modern Fender is to replace signal and coupling caps with Jupiter Vintage Capacitors.Dessigned as a replacement for the Astrons used in vintage Tweed Fender's and the blue molded caps used in brown and blackface Fenders, these caps have the warm vintage tone that is very desirable.

Also replacing the generic Illinois power filter caps with Sprague Atoms will give further body to the sound.