Push pull tube amplifier design book pdf

Classa pushpull tube power amplifier electronics diy. Lundahl transformers old fashioned 30w push pull amplifier. Design and building of a 300 w mosfet pushpull power. It is the source of the famed 510 and 520 mullard amplifiers. Diy audio books and manuals speakers, vacuum tubes, electronics. The solution to the above problem may well be the socalled push pull pp design. For me, the ultrafi was the last piece of the puzzle in my quest to design an ss amp that can rival tube amps. Two examples of semelab push pull mosfets are shown in figure 1. The only thing you have to do is to replace some transformer connections. But the gain does not stop there because both the demands on the output transformer opt and the regulation of the supply gets less. If you have not been trained to work with high voltage then have an amp technician service your amp. The survey is meant to give the reader a fair idea of how each part of how a standars electron tube amplifier works.

The mullard tube circuits for audio amplifiers book was first published in 1959 by mullard, britains premier vacuum tube manufacturer. The anodes are connected to the primary winding, the cathodes to ground circuits 1, 2, and 3, and the middle of the primary to the highvoltage supply. A class ab amplifier is defined as one in which the output device is conducting for more than 50% but less than 100% of the waveform cycle. The most popular highend tube amps in the market top tube. This classa push pull tube power amplifier uses a pair of push pull class a, ultra linear mono block tube amplifiers that can be used with several different vacuum tubes including kt77 6l6gc kt88 with a 12sl7 driver and 6no30 tubes. This pcb makes all those changes extremely easy, just some minutes soldering and the job is done. Colpitts us patent 17384 granted in 1915, although the patent does not specifically claim the pushpull connection.

Coates 2007 2012 power amplifiers introduction to power amplifiers power amplifiers amplifier circuits form the basis of most electronic systems, many of which need to produce high power to drive some output device. Dec 05, 20 heres how a push pull audio power amplifier works, using two npn bipolar transistors. With this solution you may double the output power with very few extra components except another tube, that is. A pair of audion tubes connected in pushpull is described in edwin h. The class b push pull amplifier is almost similar to the class a push pull amplifier and the only difference is that there is no biasing resistors for a class b push pull amplifier. Chokeloaded triode direct coupled to dht driver, transformer coupled to the push pull 300b output tubes. The other two can be used for either push pull or single ended. The two main types of output stages for guitar amp use are singleended and pushpull. The design of this stage takes skill and care as explained in my earlier paper. Ultralinear mode and push pull configurations were introduced respectively in section 2. To wire inphase one heater wire would be connected to pin 2 on one power tube and pin 2 on. The last few amplifiers that ive designed used pentodes and lots of nfb to get low distortion. It refers to a special case of differential circuits, where a whole signal is made up of the difference of two voltages, a negative and a positive technically speaking, only the output stage is push pull, but both are differential.

Byrith has received a number of comments and questions from builders of this amplifier. Anything less than complete conduction of all output devices is not class a as with any audio amplifier, the signal should be biased in the middle of the linear region. A perfectly balanced push pull stage will cancel all even harmonic distortion and sum odd harmonic distortion generated within the power stage. The appendix also includes performance curves, pcbs and layout suggestions for the above amplifier pdf file, 854k. This means that the two transistors are biased at the cut off point. The 6550 is rated to deliver 28 watts in the push pull triode connection, which allows a safe reserve of power handling capac ity for those who wish to design con servatively even for a large home in stallation. The 6ck4 is an indirect heated triode originally intended for tv service as a vertical deflection amplifier. The circuit structures seen in bjt and fetbased amplifiers commoncollector and commonemitter, common source and common drain, are paralleled in tube based circuitry commonplate and commoncathode. These terms refer to the amplifier output stage circuit topology, which is the way in which the components in the output stage are connected.

A push pull valve amplifier almost invariably follows one of the two schemes shown in block diagrams below. Tube amp design wikibooks, open books for an open world. Very few designs differing from these two have proven fit for real life, the quad ii being a notable exception you will find the diagram in. Thus, i was able to use my preexisting knowledge of amplifier design, coupled with. Push pull class b power amplifier analog electronics. Pushpull circuits are widely used in many amplifier output stages. The phase shifters are actually acting as balun balanced. In terms of distortion and performance, push pull amplifiers are more efficient than singleended amplifier because of its push pull arrangement. Alc samples rf envelope at amplifier input, or detects grid current. A class b pushpull amplifier is more efficient than a classa power amplifier because each output device amplifies only half the output waveform and is cut off during the opposite half. Books, tutorials, and technology for guitar amplifier circuit design. Construction of push pull class a power amplifier the construction of the class a power amplifier circuit in push pull configuration is shown as in the figure below. Many people build low power equipment and find amplifiers difficult. The amplifier changes smoothly from classab to classf as the plate voltage rises following the input signal envelope.

The class b configuration can provide better power output and has higher efficiencyup to 78. This is old schematic of fisher amplifier 70a series. Singleended class a operation is less efficient than push pull. One thing about diy audio is that it is a journey, not a destination, it.

The tube exhibits very good linearity at moderately high idle currents of around 30ma and at this level is dissipating roughly 10 watts. Never touch the amplifier chassis with one hand while probing with the other hand because a lethal shock can run between your arms through your heart. Coming into the project, i knew that i wanted an amp with roughly 60 watts of output that had two preamp channels with separate tone controls. Simple cheap 50w pa a homebrew irf510 rf amplifier. Push pull transistors semelab plc produces a wide range of push pull mosfets and this application note is intended as a guide to some circuit design principles which are particularlyappropriate when using these devices.

In my book, i explain how to change an amp from pentode push pull, into an ultra linear design and even into a triode push pull design. This book, in print from 2008 until 2020, has been updated, expanded, reorganized, and replaced by guitar amplifier electronics. I used a pushpullparallel set of 5b854m tubes, which are basically 807 tubes in a slim bottle with a loctal base. Basic theory a 21stcentury approach to understanding preamp, power amp, and power supply design. How to build a tube amplifier rob robinettes car and tube. The tube exhibits very good linearity at moderately high idle currents of around 30ma. Easy to build pushpull amplifier using plitron output and. Very few designs differing from these two have proven fit for real life, the quad ii being a notable exception you will find the diagram in the appendix together with a brief explanation. The main objective of this project was to design a 100w power amplifier with feedbackpair complementary symmetry output power transistors. The amplifier also features a unique amplifier design that, according to thule, effectively eliminates switching distortion, the kind that occurs in push pull amplifiers when then sine wave crosses from positive to negative. Step by step design of a push pull tube amplifier use all needed notions to design an entire integrated push pull vacuum tube amplifiers. Hoffman amplifiers tube amp forum, how to calculate pushpull impedence. I had in the past designed some pretty amazing ss circuits that could do warm tubelike od, but the clean aspect depth and dimension of my ss amps were noticeably lacking when abd with a good well tweaked tube amp. The results from testing the amplifiers are quite similar to the results from the oddwatt 225 6sl7 srpp kt77 classa push pull tube amplifier.

A tube amplifier chassis contains lethal high voltage even when unpluggedsometimes over 700 volts ac and 500 volts dc. The yaqin mc84l is a class a integration pushpull tube amplifier that uses a highperformance ultralinear pushpull circuit to bring rich acoustics out of your audio. This amp is called a 6v6 push pull amp, the 6v6 being the tube model, but whats this push pull business. Download a pdf schematic of the amp wiring, the driver pcb schematic showing components for this build, and the power supply pcb schematic. The one that is for the push pull amplifier only is the peak gridtogrid voltage.

El84 datasheet specifies that anode and screen voltage can be. Pushpull amplifier article about pushpull amplifier by. In pentode operation a pair of tubes will deliver 100 watts reliably. Circuit simulation a deep dive into spice tube amp modeling. This design is called quasicomplementary because transistors qj and q together perform the same function as the pnp transistor in a romp ementary pushpthe input signal is positive, pnp transistor 0. You also learn how changes in the design of a stage affect its performance. Tube amplifiers, schematics, parts, triode amplifiers. For inphase wiring you would run one heater wire from pin 9 of one preamp tube to pin 9 of the next tube. The amplifier stage is based on the compact hifi power amplifier.

Even if the phase inverter is perfectly balanced it will inevitably go out of balance when the power. Power tubes wired in push pull should also be wired inphase to take advantage of common mode noise rejection inherent in the push pull circuit. Protect tube s from excessive grid dissipation basic alc operation. I found i could work stations in about a 200km radius during the day with 5 10 watts, but at night i could work no one at all. Complementary symmetry class b and class ab power amplifiers the circuit for a typical push pull power amplifier is shown to the right figure 8. Chapter 2 teaches you how to design and interconnect all of the five stages in a basic amplifier. A very important consideration in attempting to create an amplifier with a natural characteristic is the selection of the gain devices. Figure 1 shows several push pull tube amplifiers only the power tubes and the output transformers primary winding. In a pushpull amplifier, when one tube is at the highest peak, the other is at the lowest peak. This amplifier, like the my other designs, can be connected directly to a cd player or to a dac without using a preamp. The phasesplitter is a very critical part of the pp amplifier, and its behaviour is of great importance for the performance of the amplifier. The overall schema of the power stage, including values of all components, is given in figure 48. Never touch the amplifier chassis with one hand while probing with the other hand because a lethal shock can run between your arms. A push pull amplifier is a type of amplifier that can drive current in either direction through the load.

I used a push pull parallel set of 5b854m tubes, which are basically 807 tubes in a slim bottle with a loctal base. El84 datasheet specifies that anode and screen voltage can be set to. This amplifier design uses 6ck4s in the output stage. Since 1999 welcome to almost 500 posts and to over 50 articles on amplifiers, tubebased preamps, crossovers, headphone amplifiers, singleended amplifiers, pushpull amplifiers, circlotron circuit design, hybrid amplifiers, cascode circuits, white cathode followers, groundedcathode amplifiers, tube series regulators and shunt regulators, the aikido amplifier, tranformer coupling. Do it yourself 4 watt amplifier vintage book part 3 diskonekted january 8, 2020. Measurements pushpull kt88 tube amplifier 12sl7 driver measurements were made using a hp 331a distortion analyzer, tenma low distortion signal generator 0.

Welcome to the hoffman amplifiers forum may 08, 2020, 07. It has more than a casual similarity to the first push pull el84 6bq5 oddwatt project from nearly two years ago. We adopt a push pull configuration in ultralinear mode. These books gave a background on vacuum tubes and also their applications to guitar amplifiers. It uses a single pentode stage for the preamp, a selfsplit push pull power amp which requires no phase inverter and a field coil speaker. While this is an old book it is detailed and easy to follow. This arrangement mainly reduces the harmonic distortion introduced by the nonlinearity of the transfer characteristics of a single transistor amplifier.

This classa pushpull tube power amplifier uses a pair of push pull class a, ultra linear mono block tube amplifiers that can be used with several different vacuum tubes including kt77 6l6gc kt88 with a 12sl7 driver and 6no30 tubes. It can be shown that the theoretical full power efficiency ac power in load compared to dc power consumed of a pushpull stage is approximately 78. Beside that, el34, el84, and 12ax7 vacuum tubes are used in many practical examples, to design the various parts of the circuits and to compute the values of the needed components. Western electric 845 push pull hallelujah this amplifier is also little known among the tube enthusiast and w. The very good result got with the pp2010 and availability of a pair of old 10kohm tecnotrafo italy push pull transformers have forward me to create this new amplifier. Vacuum tube circuit design guitar amplifier power amps. The guitar signal on the upper power tube grid changes the current flowing through the tube which causes a voltage drop across the cathode resistor. Singleended amplifiers tend to be bigger and more expensive than push pull, but they have a more natural transfer curve. Prevent overdrive of amplifier and resulting nonlinearity. The technique was wellknown at that time and the principle had been claimed in an 1895 patent predating electronic amplifiers. After reading these books, i felt that i was ready to start designing the amp. This knowledge is then used to design an electron tube amplifier in the software tool ltspice.

Sep 01, 2009 chapter 1 introduces basic audio engineering concepts used in tube amps, which are used throughout the book. To improve the full power efficiency of the previous class a amplifier by reducing the wasted power in the form of heat, it is possible to design the power amplifier circuit with two transistors in its output stage producing what is commonly termed as a class b amplifier also known as a push pull amplifier configuration. However, guitar amps rarely use matched valves and usually have a lessthanperfect phase inverter. Nov 19, 2015 figure 1631 shows a popular pushpull amplifier design that uses npn transistors for both output devices. The result is the fatboy 300b amp named as such because, like me, it is a tad overweight. Figure 1 shows several pushpull tube amplifiers only the power tubes and the output transformers primary winding. Class b amplifier and the classb transistor amplifier. In this arrangement, one transistor amplifies the positive half cycle whereas another. The devices should be biases so that each device conducts during its half of the cycle, plus. Tube amplifiers often fall out of stock if your favorite is available, i highly recommend snagging it. This guide discusses all relevant aspects for an integrated push pull vacuum tube amplifier design, including the power supply unit. When the anode voltages of the two vacuum tubes are given to the two ends of the output transformer, the peak of the voltage variation is therefore doubled, and the peak voltage seen by the transformer is 2225v450v. I used tango nc14 interstage and fx405 output transformers, which ive had around for a while.

Push pull amplifier circuit, operation, advantages and. Transformerless pushpull amplifiers electronics assignment. It discuss the design of the power stage, the phasesplit, and the input stage. Oddblocks classa pushpull kt88 tube amplifier 12sl7. The drive circuitry of the control grids is not shown i assume perfect. I built this amplifier so that i could be heard above the qrn and qrm on 40 meters in the evening. This project is related to the other tube amplifier projects i have posted. This book is a beginners guide that brings you, from the basic concepts of vacuum tubes, up to the design of a complete integrated push pull vacuum tube amplifier. This book first introduces the needed principles, to designing and understanding vacuum tube amplifiers. From this level up the tubes start to saturate, and the current through the control grids forces the polarization level more negatively, out from classab. A class a amplifier is defined as one in which the output device is conducting for the complete waveform cycle.