Design of an integrated push pull tube amplifier made easy

Push-Pull Amplifier is a power amplifier which is used to supply high power to the load. One transistor pushes the output on positive half cycle and other pulls on negative half cycle, this is why it is known as Push-Pull Amplifier.

The advantage of Push-Pull amplifier is that there is no power dissipated in output transistor when signal is not present. Class A configuration is the most common power amplifier configuration. It consists of only one switching transistor which is set to remain ON always. It produces minimum distortion and maximum amplitude of output signal. The stages of the Class A amplifier allows same amount of load current to flow through it even when there is not input signal connected, therefore large heatsinks are needed for the output transistors.

The circuit diagram for Class A amplifier is given below:. Class B amplifier is the actual Push-Pull Amplifier.

Review! The Muzishare X7 Tube Integrated Amplifier

The Class B amplifier circuit is biased in such a way that each transistor will work on one half cycle of the input waveform. Therefore, the conduction angle of this type of amplifier circuit is Degree. Circuit diagram for Class B amplifier is given below:. Class B generally suffers from an effect known as Crossover Distortion in which signal get distorted at 0V. We know that, a transistor requires 0.

So when AC input voltage is applied to push-pull amplifier, it starts increasing from 0 and until it reaches to 0. To overcome this problem, diodes are used for biasing, and then the amplifier is known as Class AB Amplifier. A common method to remove that crossover distortion in Class B amplifier is to bias both the transistor at a point slightly above then the cut-off point of transistor.

design of an integrated push pull tube amplifier made easy

Then this circuit is known as Class AB amplifier circuit. Crossover distortion is later explained in this article. By adding the diode, transistors are biased in slightly conducting state even when no signal is present at base terminal, thus removing the crossover distortion problem. When the input signal is positive Q1 starts conducting and produce a replica of the positive input at the output. At this moment Q2 remains in off condition. Similarly, when input signal is negative Q1 turns off and Q2 starts conducting and produce a replica of the negative input at the output.

Now why the crossover distortion is happening when V IN reaches to zero? Let me show you rough characteristics diagram and output wave form of Push-Pull Amplifier Circuit.

If V IN is equal to zero then Vout must also be equal to zero. Recommended Posts.I can build virtually any custom amplifier you desire. I have experience with many types of tubes and circuits, and can discuss specifics and offer advice based on your needs.

I can use transformers you supply, or attempt to procure vintage transformers as needed. Please spend a little time looking over the pictures and reading the descriptions of a few of the amplifiers I have built. These tubes were the last gasp of vacuum tubes and were developed almost solely for military applications. They are used in missile guidance systems and portable radios. They are used in combination with transistors in many commercial radios.

They are also used in a variety of other commercial applications, such as hearing aids. Early versions of these tubes operated with plate voltages of about volts, but later versions used as little as 22 volts for the plates. Some recent applications for these tubes have been for preamplifiers for condenser microphones, headphone amps and effects boxes for guitars.

There are several examples of amplifiers I have built. Mono Blocks SE with separate high voltage power supply. Stereo Amplifier SE with outboard high voltage power supply. Stereo Amplifier SE with 12 volt power. The chassis and front panel were in very bad shape and the original output tubes used are obsolete and very difficult to find.

The 6AQ5 tubes are the miniature version of the 6V6. They are relatively inexpensive and easy to find. This amplifier puts out about 10 watts per channel and is perfect for an office or a bedroom.

Reading Tube Amp Schematics

It featured two input selections for use with a tuner and MP3 player. This was built on a stainless steel chassis very difficult to machine and utilizes a pair of Dynaco SCA 35 outputs and an Edcor power transformer. This amplifier was designed by Bruce Heron and operates in pure Class A mode. It uses constant current devices on the output cathodes that keep the outputs in Class A mode. This amplifier also uses an SPRP driver circuit.

It works great with Russian tubes. They have heavier glass and a larger envelope and are very rugged.In our previous article, we have introduced you to amplifiers and its types. Here in this article, we are going to explore about Push-Pull Amplifierits circuit, operation, advantages, and disadvantages in detail.

A push-pull amplifier is a type of amplifier that can drive current in either direction through the load. In this arrangement, one transistor amplifies the positive half cycle whereas another transistor amplifies the negative half cycle of the signal i. All audio power amplifiers used in the record player, transistor radio receivers, tape recorders etc make use of push-pull arrangement because these systems are usually operated by batteries where efficiency is the primary factor.

Both the transistors are operated in class B operation i. Through a driver transformer, the input signal is given to the circuit from the driver stage. The secondary of driver transformer is center tapped which supplies equal and opposite voltages to the base circuits of the two transistors. Cente tap primary of the output transformer is connected to the collector circuit and at the secondary side, the load is connected. To get maximum output from the load, a suitable impedance matching is obtained by designing proper turn ratio of the output transformer.

In a push-pull ampthe input signal appears across the secondary AB of the driver transformer. By this, the base-emitter junction of the transistor T1 becomes forward biased and T2 becomes reverse biased.

This further allows the current conduction across the transistor T1 and makes the transistor T2 in the cut-off state.

Therefore, the first half cycle of the signal is amplified by the transistor T1 and appears in the upper half of the primary of the output transformer. So now, the base-emitter junction of the transistor T2 is forward biased and T1 is reverse biased which allow the current conduction across the transistor T2 and make the transistor T1 in the cut-off state.

Therefore, the first half cycle of the signal is amplified by the transistor T2 and appears in the lower half of the primary of the output transformer. Complete sine wave output in the secondary is obtained when the center tapped primary of the output transformer combines the two halves of the cycle. By proper impedance matching, maximum power can be transferred to the load.

DIY and Hi-Fi Audio Schematics

As we know, due to the nonlinearity of the transistor, even if the input is sinusoidal, the output current contains harmonics.

The output i. In this amplifier, the voltage induced in the secondary of the output transformer is proportional to the difference between the two collector currents i. Note: In push-pull amplifiers, all even harmonics get canceled. Push Pull Amplifier Advantages:. Push Pull Amplifier Disadvantages:. Hope you all like this article. For any suggestions please comment below. We always appreciate your suggestions. Rate the article below. Thanks Sahil, If you want to know about any topic related to this blog, shoot your question in comments.

Plz help Is operation means working of push pull Also is there any difference between class B amplifier and push pull amplifier. Hi Shah Burhan, Thanks for commenting. Yes, operation means working of a push-pull amplifier. There can be a class A push-pull too. Not reserved for class B only. The plain Class B is able to amplify either positive or negative half cycle of the full signal waveform. So, obviously, we need two class B stages connected as push pull to have the full cycle of the input signal amplified.One thing about DIY audio is that it is a journey, not a destination, it never ends.

One project leads to another. The only limits are time and money. DIY audio is a lot about perfection.

design of an integrated push pull tube amplifier made easy

While I was quite happy with my previous tube amplifier projects, I felt there was room to improve here comes the journey again. I like to be involved in the music. If anything sticks out, it will degrade the experience.

So I tend to like smooth response, lots of detail, wide soundstage and full spectrum of sound.

How To Build a Tube Amplifier

These amps deliver all that in quantity. Regardless of what tubes I used for outputs, the sound is "silky" and refined. All Rights Reserved. I initially used KT77 tubes as I was familiar with the sound and it would be a good starting point.

I tried the amp with Electro-Harmonix KT88 tubes. Using the EH KT88 tubes has been a mixed situation. Additionally they don't behave well in this particular amp. I suspect the reason is related to thermal problems and the use of common joint cathode bias. The circuit allows for adjustment of the bias the 25 ohm variable resistor but the EH tubes do not stay in sync.

One or the other tube not predictable which one will start to conduct more than its fair share of the current. With current balance being an important consideration of the design this is not good. It is possible that this is a situation with just the one brand of KT88s. I have since then acquired a set of new production Gold Lion KT88 tubes and they behave perfectly.

I will not further speculate why the one brand works and the other doesn't. It is just the way things are. An alternative driver for 9 pin application is the type This tube will directly substitute for the octal 12SL7 in this circuit. Contact with the voltages at various points in this circuit can be fatal.Build an inexpensive yet authentic Single-Ended Triode Amplifier.

This venerable circuit topology, essentially the simplest possible tube amplifier, has reached almost cult status in today's audiophile circles. What is it about this circuit that commands such a loyal following? Here is your opportunity to explore the possible answers for yourself, at very reasonable cost. This project is recommended for beginning vacuum-tube do-it-yourselfers.

However, some previous experience with building vacuum tube circuits is highly recommended. A very basic electronics knowledge is assumed, as are the soldering and mechanical skills required to assemble and wire the project. The information provided here is believed to be correct, but the author and Dogstar Music assume no liability for damages incurred through use or misuse of the information provided herein.

With the disclaimer out of the way, I can only add that this is the ideal project for exploring the mystique of the single-ended triode amplifer. If you like the sound of the SET topology, you just might find yourself using the MiniBlok as a warmup for a larger project. If not, you haven't invested much, and might still find MiniBlok useful as a "center-channel" fill-in amplifier to add some depth and colour to your stereo system.

All rights reserved. This site may be freely linked, but none of the contents may be posted anywhere else without express permission of the copyright holder. The information presented here may be used for personal, non-commercial use only. Any commercial applications of this design or any part thereof requires previous licensing arrangements with the author and copyright holder, Fred Nachbaur.

Contact : You may contact me regarding this project at fnachbaur netscape. While I'm not keen on answering questions covered in the article, I'd be happy to help out with any concerns not adequately addressed on this site. To find out what other kinds of trouble I get into, check out my sites listed below:.The sooner you learn to read amplifier schematics the sooner you'll be able to analyze classic amp circuits and learn how the masters of amp design voiced their amps.

It's much easier to analyze an amp circuit by studying its schematic than looking at its layout diagram. The key to learning to read amp schematics is to start small with the Fender 5F1 Champ amplifier schematic and focus on one component at a time to keep from being overwhelmed. Once you can read the simple Champ schematic you'll be able to figure out more complicated amp schematics.

If you have not been trained to work with high voltage then have an amp technician service your amp. 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. Use just one hand when working on a powered amp. See more tube amplifier safety info here. We'll start with learning pretty much all the schematic symbols you'll need for tube amps in this little schematic legend:. Common amp component symbols.

You can right-click this graphic and select "Open image in new tab" or "Save image as" to make it easier to access while looking at the schematics below. Lets start by looking at the simple standard tube amplification circuit that you will see again and again as you study tube amp schematics.

Guitar signal shown in pink enters the tube on the left at "AC Signal In. The Grid Leak resistor bleeds off unwanted captured electrons grid current to keep the grid at zero volts DC. The optional Grid Stopper resistor filters high frequencies above human hearing. The Cathode resistor generates the bias voltage between the cathode and grid. The optional Bypass capacitor boosts gain by acting as an electron reservoir. The tube's Cathode is the source of electrons.

The Grid is the "valve" that controls the flow of electrons through the tube. The Plate is charged with high voltage DC to pull electrons from the cathode, through the grid to the Plate.

The Load resistor transforms the circuit from a current amplifier to a voltage amplifier. The Coupling cap keeps the Plate's high voltage DC from flowing downstream but allows the guitar AC signal voltage to pass. This tube is a 'triode' which means it has three electrodes: the grid, plate and cathode. Only 26 electronic components are needed to make a great sounding amplifier. Every component's function is listed. The signal flow in red starts at Input Jack 1 at the far left.

V1A is one half of tube V1, V1B is the other half. The component numbers match the layout below so you can compare the layout and schematic.

Click the image for the full size schematic.Ever wanted to build a highly dangerous, inefficient, yet awesomely retro piece of electronics? Well, I have. That's pretty much what a tube amp is. Vacuum tubes are old electronic components that act like transistors, controlling a lot of current with a little current. You usually hear about tubes being used in guitar amplifiers, because they distort in a way that suits guitar playing.

However, tubes can also be used to amplify a stereo signal from another audio source such as a CD or MP3 player. Tube amps, unfortunately, aren't the most practical things in the world; they consume a great deal of power, get very hot, and are big. That being said, they look damn cool, and some people seem to think they sound pretty nice, too. You can learn a lot about electricity and electronics from a project such as this.

Going through the process of purchasing parts, planning, and executing is a useful experience for any maker. Keep in mind that I am just a dude on the internet - take everything I say with a grain of salt.

Except, of course, for these next few sentences. This project is dangerous in a very serious way. It involves high voltages and a lot of current that can make you feel decidedly unpleasant or even decidedly dead. If you decide to work on it with the power on, be careful. Some of the capacitors in this amp will hold onto a charge for a long while after the power has been switched off.

Discharge all capacitors through a resistor connected to ground, preferably with a voltmeter across it to be absolutely sure the cap has completely discharged. When testing the amp out for the first time, use something like a twelve volt power brick instead of plugging directly into the wall, just to be safe, as well as to prevent things from exploding or melting.

An old trick is to keep your left hand in your back pocket all the time, so if you do get shocked, it hopefully won't reach your heart. Did you use this instructable in your classroom?

Add a Teacher Note to share how you incorporated it into your lesson. Parts The guy who originally designed this amp, Poindexter of Audiotropichas a wealth of information on his site about the parts he used. His device, called the Musical Machine, is made up of some very nice, but very expensive audiophile-type components high quality specialty hookup wire, extra fancy solder. So, for that reason, I have built the same circuit as Poindexter, but with cheaper and more available parts.

What You'll Need The amp consists of two sections, the audio circuit and the power supply. Let's look at the parts in both. Enclosure You're going to need something to put your amp in, and there are definitely certain considerations to be taken when picking an enclosure. Transformers and especially the tubes themselves can get very hot, and so need to be in a well ventilated kind of area, preferably jutting out the top of the case.

Unfortunately, in my case, I foolishly chose an enclosure purely for its looks, which ended up being a bit of headache. I picked an old wooden cutlery case, which just happened to have rather thick panels, making it painful to mount components that were designed to be mounted on circuit boards or thin metal project boxes.

So, unless you want to spend the time making that kind of case work, I'd say go with something more conventional. Transformers What to Buy You'll be making the audio circuit twice over since this is a stereo amp, after all, and so you'll need two output transformers.

design of an integrated push pull tube amplifier made easy

Poindexter uses very fancy special order transformers that are way out of my price range, so I settled for a Hammond D, which, as far as I can tell, works fine. There are four transformers in the power supply, one for the heating filaments in the tubes Hammond N6one for the main positive supplies Hammond Gone for the negative supplies an Amveco toroidand a 'choke' transformer Hammond Q. A choke isn't really a transformer but an inductor.

Basically, the function of a choke is similar to that of a capacitor in parallel, it resists sudden changes in current, and so acts as a filter.

Where to Buy It I got these transformers from Angela Instruments which has a ton of old high quality audio components. Another good place is Parts Connexion. The Amveco toroid I ordered from Digi-Key part no. For the preamp tubes, we have two tubes which are double triodes, meaning each tube actually contains two triodes.

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