My curiosity has spiked about the application of the transistor in a SET amp.
I was wondering if the slew rate would be as fast in both directions, even under load.
I have been thinking of transistors like a muscle, that can pull in one direction, but only release in the other.
How can one transistor push equally as good as it pulls, ? or does it ??
I suspect that they do not, except at low power. (which most are)
I've looked at some schematics, and I am seeing a load resistor, as well as an output. - so I guess the resistor is there to help make sure the voltage
falls as fast as it needs to?
- to keep the speaker cone moving back as fast as the voltage is dropped especially at higher volumes.
- so the speaker isn't just coasting when the transistor is turning off, but downtracking, made to follow the signal, pulling it towards zero.
Please don't respond if you don't have a constructive reply.
I have years of experience repairing amps, and am not a novice.
I understand that I may not reach your vocabulary or speak your language.
So, a nice answer, or move on please, THANK YOU!
I was wondering if the slew rate would be as fast in both directions, even under load.
I have been thinking of transistors like a muscle, that can pull in one direction, but only release in the other.
How can one transistor push equally as good as it pulls, ? or does it ??
I suspect that they do not, except at low power. (which most are)
I've looked at some schematics, and I am seeing a load resistor, as well as an output. - so I guess the resistor is there to help make sure the voltage
falls as fast as it needs to?
- to keep the speaker cone moving back as fast as the voltage is dropped especially at higher volumes.
- so the speaker isn't just coasting when the transistor is turning off, but downtracking, made to follow the signal, pulling it towards zero.
Please don't respond if you don't have a constructive reply.
I have years of experience repairing amps, and am not a novice.
I understand that I may not reach your vocabulary or speak your language.
So, a nice answer, or move on please, THANK YOU!
You can have SE with two same sex transistors and output is in between. The two transistors can still push and pull. A Circlotron does this.
https://www.passdiy.com/pdf/Build The Amazing FET Circlotron.pdf
https://www.passdiy.com/pdf/Build The Amazing FET Circlotron.pdf
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Hi LiquidMids,
The reason why most of experienced people don't like to answer this kind of questions - why do they have to spend their time, providing basic education? It's pretty easy to read about the SE class A operation in many well-known books on audio amplifiers design.
SE class A cascades are used not only as an output stage. For example, there are lots of front-end topologies, utilising SE class A operation.
In a single-ended cascade, there is a driving transistor and there is a load. Driving transistor pulls the output to one side, the load pulls it to the other side.
The simplest load is a resistor. But not the best one. In order to reduce distortion, the dynamic load - a constant current source (CCS) is used. Having high output impedance, it pulls the output with practically constant current (which is the stage's quiescent current). In a well-designed SE cascade, the output signal rise and fall times will be practically equal.
A good example of a SE class A circuit is a classic "blameless" topology - a single-ended VAS with CCS as dynamic load.
Nelson Pass has designed a number of amplifiers with SE class A output stage - see more details on his web site.
Cheers,
Valery
The reason why most of experienced people don't like to answer this kind of questions - why do they have to spend their time, providing basic education? It's pretty easy to read about the SE class A operation in many well-known books on audio amplifiers design.
SE class A cascades are used not only as an output stage. For example, there are lots of front-end topologies, utilising SE class A operation.
In a single-ended cascade, there is a driving transistor and there is a load. Driving transistor pulls the output to one side, the load pulls it to the other side.
The simplest load is a resistor. But not the best one. In order to reduce distortion, the dynamic load - a constant current source (CCS) is used. Having high output impedance, it pulls the output with practically constant current (which is the stage's quiescent current). In a well-designed SE cascade, the output signal rise and fall times will be practically equal.
A good example of a SE class A circuit is a classic "blameless" topology - a single-ended VAS with CCS as dynamic load.
Nelson Pass has designed a number of amplifiers with SE class A output stage - see more details on his web site.
Cheers,
Valery
Your "muscle" analogy is wrong ... or at least quickly becomes inaccurate as soon as you go to too much along that path.
By the way, same happens with the "water in a pipe" electrical analogy, for basically the same reason: they are both "analogies"
To correct your example a little:
that muscle is not alone, but pulling a spring.
when muscle moves (pulls) a load (a certain weight) towards one side, it is also stretching said spring.
When muscle relaxes, the spring pulls the load (weight) the other way, with equal force.
The spring is the output transformer or load inductor.
Thanks for clearly explaining this, makes good sense.
I look forward to hearing this design! so few parts to match, I bet they are
really good sounding when set up right.
I look forward to hearing this design! so few parts to match, I bet they are
really good sounding when set up right.
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