This book moves beyond general principles of tube amplifier design to carry out an intense examination of one of the most famous circuits of the rock era. The book begins with the 5F6A's relatively simple triode preamps (bypassed cathode resistor, unbypassed cathode resistor, and cathode follower) and then progresses through the mathematically challenging tone stack, long-tailed-pair phase splitter, and push-pull power amp. Every formula for every tube is derived in all its gory detail. The author's methods include the classic load lines and composite characteristic curves of Frederick Terman and the Radiotron Designer's Handbook as well as more modern techniques like linear regression and the Discrete Fourier Transform. Special attention is paid to quantifying the push-pull amplifier's nonlinear response and to analyzing power supply voltage sag as it reacts over time. This expanded, second edition includes an enlarged, fold-out schematic of the Bassman and a new chapter on the Marshall JTM45, which is almost a direct copy of the 5F6-A. The Bassman 5F6A circuit has inspired guitar amplifier designs for over four decades, so sharpen your pencil, fire up your calculator, and find out what makes this amp rock!
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Why would a member of the IEEE Circuits and Systems Society, an organization dedicated to advancing the state of the art in electronics, write an entire book about the design of a vacuum tube amplifier manufactured more than four decades ago? Even back in 1959, the Bassman's innovation must have paled in comparison with the technological leaps being made by space-age transistor circuits.
To understand the motivation behind the book you need to understand what the tweed Bassman means to guitar players. To generations of professional musicians the Bassman's mix of harmonic overtones is the holy grail of tone, the perfect balance between clean reproduction and distortion-driven tonal ecstasy.
Its place in history is ironic, because the 5F6A wasn't even designed for the guitar - as its name implies it was intended to be a bass amplifier. Yet today more than ever the amp's sound hits the mark with guitar players the world over. More than forty years after the original 5F6A ceased production many of the best guitar amps, Marshalls in particular, are still based on its long-tailed-pair, negative feedback circuit design. It is to this lasting legacy that the book pays tribute.
The book has a 7-inch by 9-inch paperback format with a 1.7 mil laminated cover. It includes a bound, 18-inch by 9-inch Z-folded insert with the complete 5F6A schematic and the original manufacturer's voltage measurements.From the Author:
This expanded, second edition introduces some new topics. Complete headroom analysis is performed, both for the individual stages and for the system as a whole, for the purpose of determining where distortion is likely to break out first depending on the control settings. The Marshall JTM45, which is almost a direct copy of the 5F6-A, is also analyzed to compare its significant differences, most notably the substitution of a 12AX7 in the first preamp, an additional bypass capacitor in the bright channel for the lead model, and triple the negative feedback voltage to the phase splitter.
This edition also takes a completely different approach to estimating the supply voltage sag at maximum power. As was noted in the first edition, the ultimate supply voltages reached are very sensitive to slight changes in the signal level and a number of approximations have to be made to keep the problem complexity in check, so even in this edition the supply voltage sag is more or less a ballpark estimate for what is encountered in practice. It is important to address this subject, however, because the sag that is induced by the vacuum tube rectifier and class AB output stage is an essential element of the Bassman's legendary sound. The new methods introduced here are both simpler and more accurate than what was used in the previous edition.
My thanks to the risk-takers who bought the first edition, gave me highly valuable feedback, and encouraged me to continue this work. My thanks also to Fender Musical Instruments Corporation for giving me permission to include their annotated schematic. The Bassman's classic design may not represent new technology, but to generations of performers and music lovers alike it is difficult to find a more magical ensemble of electronic components or a longer-enduring legacy than the 5F6-A.
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Book Description Pentode Press, 2005. Paperback. Book Condition: New. book. Bookseller Inventory # 0976982218
Book Description Pentode Press, 2005. Paperback. Book Condition: New. book. Bookseller Inventory # 976982218