Items related to Valve Amplifiers. Valve Amplifiers. Morgan Jones. Publisher: Newnes , This specific ISBN edition is currently not available. View all copies of this ISBN edition:. Synopsis About this title Valve Amplifiers has been recognized as the most comprehensive guide to valve amplifier design, analysis, modification and maintenance. Review : " Buy New Learn more about this copy. About AbeBooks. Customers who bought this item also bought.
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Valve Amplifiers Morgan Jones. Published by Newnes New Paperback Quantity Available: Chiron Media Wallingford, United Kingdom. Seller Rating:. Valve Amplifiers Paperback Morgan Jones. Book Depository hard to find London, United Kingdom. Description Postage and payments.
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About this product. Valve Amplifiers, Fourth Edition Valve Amplifiers has been recognized as the most comprehensive guide to valve amplifier design, analysis, modification and maintenance.
It provides a detailed presentation of the rudiments of electronics and valve design for engineers and non-experts. The source also covers design principles and construction techniques to help end users build their own tool from scratch designs that work. The author's approach walks the reader through each step of designing and constructing, starting with an overview of the essential working principles of valve amplifiers, the simple and complex stages, the process of linking the stages, and completing the design.
The book is comprised of seven chapters all of which include a DIY guide discussion of practical aspects. The text starts with familiarization of the fundamentals of electronics, which are essential for designing and building valve amplifiers. Particular attention has been paid to providing solutions for questions that are commonly asked and faced by beginners in valve designing and construction.
Valve Amplifiers is a masterful hands-on guide for both experts and novices who work with tube audio equipment, and for electronic hobbyists, audio engineers, and audiophiles. Methods of Payment Paypal is our preferred online and mobile payment method. Delivery Information How long will it take to get my order to me? The following should be used as a guide to delivery times:. International orders are sent by a tracked service.
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The following circuits are simplified conceptual circuits only, real world circuits also require a smoothed or regulated power supply, heater for the filaments the details depending on if the selected valve types are directly or indirectly heated , and the cathode resistors are often bypassed, etc. The basic gain stage for a valve amplifier is the auto-biased common cathode stage, in which an anode resistor, the valve, and a cathode resistor form a potential divider across the supply rails.
The resistance of the valve varies as a function of the voltage on the grid, relative to the voltage on the cathode.
Building Valve Amplifiers by Morgan Jones - Read Online
In the auto-bias configuration, the "operating point" is obtained by setting DC potential of the input grid at zero volts relative to ground via a high-value "grid leak" resistor. The anode current is set by the value of the grid voltage relative to the cathode and this voltage is now dependent upon the value of the resistance selected for the cathode branch of the circuit.
The anode resistor acts as the load for the circuit and is typically order of times the anode resistance of the valve type in use. The output from the circuit is the voltage at the junction between the anode and anode resistor. This output varies relative to changes in the input voltage and is a function of the voltage amplification of the valve "mu" and the values chosen for the various circuit elements.
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The signal is usually coupled from stage to stage via a coupling capacitor or a transformer, although direct coupling is done in unusual cases. The cathode resistor may or may not be bypassed with a capacitor. Feedback may also be applied to the cathode resistor. A simple SET power amplifier can be constructed by cascading two stages, using an output transformer as the load. Two triodes with the cathodes coupled together to form a differential pair. This stage has the ability to cancel common mode equal on both inputs signals, and if operated in class A also has the merit of having the ability to largely reject any supply variations since they affect both sides of the differential stage equally , and conversely the total current drawn by the stage is almost constant if one side draws more instantaneously the other draws less , resulting in minimal variation in the supply rail sag, and this possibly also interstage distortion.
Two power valves may be triodes or tetrodes being differentially driven to form a push—pull output stage, driving a push—pull transformer load. This output stage makes much better use of the transformer core than the single-ended output stage. A long tail is a constant current CC load as the shared cathode feed to a differential pair.
In theory the more constant current linearises the differential stage. The CC may be approximated by a resistor dropping a large voltage, or may be generated by an active circuit either valve, transistor or FET based. The long-tail pair can also be used as a phase splitter. It is often used in guitar amplifiers where it is referred to as the "phase inverter" to drive the power section. As an alternate to the long-tail pair, the concertina uses a single triode as a variable resistance within a potential divider formed by Ra and Rk either side of the valve.
The result is that the voltage at the anode swings exactly and opposite to the voltage at the cathode, giving a perfectly balanced phase split. Using a double triode typically octal or noval to form a SET input buffer giving gain to then feed a concertina phase splitter is a classic push—pull front end, typically followed by a driver triode and triode or pentode output stage in ultra linear in many cases to form the classic push—pull amplifier circuit.
The push—pull output circuit shown is a simplified variation of the Williamson topology , which comprises four stages:. The cascode a contraction of the phrase cascade to cathode is a two-stage amplifier composed of a transconductance amplifier followed by a current buffer.
In valve circuits, the cascode is often constructed from two triodes connected in series, with one operating as a common grid and thus acting as a voltage regulator , providing a nearly constant anode voltage to the other, which operates as a common cathode. This improves input-output isolation or reverse transmission by eliminating the Miller effect and thus contributes to a much higher bandwidth , higher input impedance , high output impedance , and higher gain than a single-triode stage.
A pentode has an additional suppressor grid g3 to eliminate the tetrode kink. This is used for improved performance rather than extra gain and is usually not accessible externally. Some of these valves use aligned grids to minimise grid current and beam plates instead of a third grid, these are known as " beam tetrodes ". In , Alan Blumlein originated a configuration between a "triode strapped" tetrode and normal tetrode, that connects the extra grid screen of a tetrode to a tap from the OPT part way between the anode voltage and the supply voltage.
This electrical compromise gives a gain and linearity equal to the best traits of both extremes. By the late s, this design became the dominant configuration for high-fidelity PP amplifiers. Julius Futterman pioneered a type of amplifier known as " output transformerless " OTL. These use paralleled valves to match with speaker impedances typically 8 ohms. This design require numerous valves, run hot, and because they attempt to match impedances in a way fundamentally different from a transformer [ citation needed ] , they often have a unique sound quality.
Some valve amplifiers use the single-ended triode SET topology that uses the gain device in class A. SETs are extremely simple and have low parts count. Such amplifiers are expensive because of the output transformers required. This type of design results in an extremely simple distortion spectrum comprising a monotonically decaying series of harmonics.
Some consider this distortion characteristic is a factor in the attractiveness of the sound such designs produce. Compared with modern designs SETs adopt a minimalist approach, and often have just two stages, a single stage triode voltage amplifier followed by a triode power stage. However, variations using some form of active current source or load, not considered a gain stage, are used. The typical valve using this topology in rare current commercial production is the B , which yields about 5 watts in SE mode. Rare amplifiers of this type use valves such as the or , capable of about 18 watts.
These valves are bright emitter transmitting valves, and have thoriated tungsten filaments which glow like light bulbs when powered. See paragraphs further down regarding high-power commercially available SET amplifers offering up to 40 watts with no difficulty, following the development of output transformers to overcome the above restrictions. The pictures below are of a commercial SET amplifier, and also a prototype of a hobbyist amplifier.
One reason for SETs being usually limited to low power is the extreme difficulty and consequent expense of making an output transformer that can handle the plate current without saturating, while avoiding excessively large capacitive parasitics.