The Vibrolux, a vacuum tube-based electric guitar amplifier by Fender, is a highly sought-after vintage guitar amplifier. The amp was primarily manufactured between the late 1950s and the 1970s. The worth of your Vibrolux amp largely depends on the year it was made. Though it's possible to determine the general time period in which the amplifier was made, the only way to identify the exact year a Fender amp was made is by the serial number.
Unplug the amplifier's power cable and disconnect the 1/4-inch speaker cable connecting the amplifier to its external speaker cabinet.
Relocate the amplifier to a flat work surface. Rotate the amplifier so the back is facing you. Loosen the Phillips-head screws fastening the amplifier's back panel in place. Remove the back panel to reveal your amplifier's tubes and internal circuitry.
Locate the tube chart inside the amplifier. This is a small piece of paper detailing the amplifier's tube schematics. The amplifier's serial number is located on the tube chart.
Use the following serial number chart to determine the year your Fender Vibrolux amplifier was manufactured:
Vibrolux 5F11 1956: F00001 to F00300 1957: F00300 to F00900 1958: F00900 to F01500 1959: F01500 to F02800 1960: F02800 to F04000 1961: F04100 to F04400
Vibrolux 6G11 and 6G11-A 1961: 00100 to 00700 1962: 00700 to 03700 1963: 03400 to 05500
Vibrolux AA763 1964: A00100 to A01300
Vibrolux Reverb AA864 1964: A00100 to A00800 1965: A00800 to A03600 1966: A03600 to A08300 1967: A08300 to A10700
Vibrolux Reverb AA864, AA964, AB568 and AA270 1967: A10700 to A11000 1968: A11000 to A12000 1969: A12000 to A13700 1970: A13700 to A23400 1971: A23400 to A24500 1972: A24500 to A25000 1973: A25000 to A27000 1974: A27000 to A31500 1975: A31500 to A33000 1976: A33000 to A34000
Vibrosonic Reverb 1972: A44000 to A50500 1973: A50500 to A68000 1974: A68000 to A99999 1975: A81000 to A99999 and B01000 to B15000 1976: B15000 to B68000
Replace the amplifier's back panel and its retaining screws.
Some older Fender amplifiers have a production stamp on the amplifier with the date the amp was manufactured. These are extremely rare.