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GlassWare Audio Design Software

TCJ Push-Pull Topologies

TCJ Push-Pull Calculator covers eight different push-pull output stage topologies:   

 

1.         Cathode-Follower Totem Pole Amplifier

2.         Grounded-Cathode Totem Pole Amplifier

3.         Mid-Referenced Totem Pole Amplifier

4.         Circlotron Amplifier (simple)

5.         Right-Grounded Circlotron Amplifier

6.         Grounded-Cathode Transformer-Coupled
    fixed bias) Amplifier  

7.         Grounded-Cathode Transformer (cathode        bias) Amplifier

8.         Cathode-Follower Transformer-Coupled

 

Although there are many more push-pull topologies, such as the Broskie and White cathode followers or the SRPP, these eight topologies are the most suitable power amplifier output stage topologies.

 Select a topology from the drop-down box. TCJ Push-Pull Calculator will then limit the variables to the chosen topology. The “Calculate” button must be pressed after each change in topology.

 
 Bold new output stage topologies cannot be rendered, but then bold new output stage topologies are rarer than bold new computer operating systems, political philosophies, or burgers at your favorite fast-food restaurant. (The old and unoriginal are simply jumbled and reconfigured into the seemingly new and bold more often than any advertising agency is likely to confess.) On the other hand, this limitation allows the program to tabulate useful  results readily. Although more flexible, SPICE is not as friendly nor as quick to use, being more like a spreadsheet than a calculator.  There are no input, phase splitter, or driver stages in TCJ Push-Pull Calculator, only the output stage. Why just the output stage? Two reasons: the output stage is the star of the amplifier, with the other stage playing only supporting roles (of course one bad player can ruin a show just as one bad part can ruin an amplifier, but without a star, you don't have much of a show: the audience didn't pay to hear only the backup band an Elvis Las Vegas show).

 

Second, my experience with many tube enthusiasts is that too many variables can only cause grief. For example, imagine an actual amplifier in use with one major problem: one of the resistors used in setting the negative bias has opened, turning the class-AB amplifier into a class-B amplifier. It sounds bad. Most of your audiophile friends recommend a different brand of coupling capacitors or a different type of resistors. Others insist that RCA tubes should never be used as input tubes, while others claim that replacing the coupling capacitor with an interstage transformer will solve all problems. If the amplifier consisted of only the output stage, at least we would cut down the amount of audio-advice noise by tenfold. This time a little more seriously, with either a tube (or solid-state) power amplifier, getting the output stage straight is primary (and difficult enough in itself); but once you do have it set straight, the next step is to record just what the output stage needs to function well, then find a way to give it what it needs. This means the next stage to be set straight is the driver stage, then the phase splitter, and finally, the input stage. Each step we move away from the output stage becomes easier to design, as less is demanded from it.