Dating old fender amps

18-Jan-2020 13:09 by 6 Comments

Dating old fender amps

As is typical with guitar amplifiers there is a lot of myth going around, sometimes surrounding a nucleus of fact.Many people believe that if they do not see two transformers sitting on the chassis, then it is a Widowmaker. In the olden days many manufacturers put smaller transformers (usually output transformers) INSIDE the chassis.

These were used in hundreds of thousands, if not millions, of “All American Five” tabletop radios dating back to the 1930′s or 1940′s.This Article is designed to assist in dating and/or identifying instruments manufactured or distributed by Gibson Guitar Corp.Please note that most of this information relates to serial numbers used from 1975 to present.The tube heaters on these are wired in series to effectively reduce the wall voltage (it’s spread over their resistances), and the tubes are not your typical Fender-type tubes, which cannot easily operate this way.For a schematic example of this type of amp, see the Harmony H-400: In this example they used a small transformer for the heater of the 12AU6, but the 50C5 and 35W4 heaters have no transformer isolating them from the wall outlet voltage.The only difference is the addition of this batch indicator.

Les Paul Classic: This model features an ink stamped serial number with no “MADE IN USA” (just as we used on the original 1952-1960 Les Pauls).The chassis was maintained at RF ground (for shielding) by a bypass capacitor (typically 0.05 µF to 0.2 µF) usually with a resistor connected across it (typically 220 kΩ to 470 kΩ , although values as small as 22 kΩ were sometimes used or the resistor was simply omitted).See here for a typical schematic of a 1948 model AC/DC radio with a 220K isolation resistor.“Widowmaker” refers to amps that can kill you because they are not grounded and can, in fact, put 117 volts AC through your body.Typically these are amps that do not have a power transformer.Therefore your guitar strings will also connect to this circuit.