Guitar Amplifier Electronics: Fender Bassman
by Richard Kuehnel
Fender designed the Bassman in 1952 to be an amplifier for its new Precision Bass. The amp had a 15-inch speaker with a closed back and used a pair of 5881 beam power tetrodes for lots of volume. Throughout the decade it would be modified and improved until culminating in the model 5F6-A.
Ironically it didn't quite make it as a bass amp, but the musical tones it created from a guitar made history. The Bassman's long-tailed-pair phase inverter with negative feedback became the foundation for many great rock and blues sounds. Many other amplifier manufacturers created new Bassman-derived designs that themselves became the legendary instruments of a rock generation. For more than half a century the 5F6-A circuit has been tweaked, enhanced, and re-introduced under many different logos, and the late-1950's original has become one of the most iconic guitar amplifiers of all time.
Fender's product line represents a master class in evolutionary design. For this reason, we begin our circuit exploration with the TV front and wide panel 5B6. We also examine the narrow panel 5E6, 5E6-A, and 5F6, because they are major milestones in the evolutionary development of the 5F6-A. With each model we explain system design concepts, the motivations underlying design changes, stage-by-stage circuit operation, and overall system performance. Analysis includes a stage-by-stage profile of audio signal levels, system voicing, harmonic distortion, intermodulation distortion, and overdrive dynamics.
Author: Richard Kuehnel is a member of the Circuits and Systems Society of the Institute of Electrical and Electronic Engineers.
|Item Height||0.44 in.|
|Item Length||9 in.|
|Item Width||7 in.|
|Page Count||162 pages|
|Packaging Dimensions||9 in. × 7 in. × 0.5 in.|
|Weight (Packaging)||0.782 lbs.|
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What you will get out of this book depends on what you need. As with all of Kuehnel's books you can be blown away by calculations that prove the characteristics described in each model or they can serve as a reference if that type of detail is what you are working on. This book describes all the versions of Bassman (and by association some other Fender circuits) up until the end of the tweed era. I have gained insight many times that has influenced me more than I can note. Every facet of tube amp design is addressed in such detail that I am regularly rereading and coming away with something I can use.
Highly recommended reading (and studying).