An LTP, or Long-tailed Pair, circuit is a type of circuit topology that can be used in amplifier designs. It can be used to convert a voltage feedback scheme into a current feedback scheme.
In a typical voltage feedback circuit, a small portion of the output voltage is fed back to the input and compared to the original input voltage. The difference between the two voltages is used to adjust the gain of the amplifier.
An LTP circuit uses a pair of transistors, with one transistor connected in a common-base configuration and the other in a common-emitter configuration. This circuit topology allows for a high input impedance and a low output impedance, which can be used to convert the voltage feedback to a current feedback.
The current flowing through the common-emitter transistor is proportional to the input voltage. By using the current flowing through the common-emitter transistor as a feedback signal, the circuit becomes a current feedback amplifier, which allows for a faster response time and better bandwidth than a traditional voltage feedback amplifier.
In a typical voltage feedback circuit, a small portion of the output voltage is fed back to the input and compared to the original input voltage. The difference between the two voltages is used to adjust the gain of the amplifier.
An LTP circuit uses a pair of transistors, with one transistor connected in a common-base configuration and the other in a common-emitter configuration. This circuit topology allows for a high input impedance and a low output impedance, which can be used to convert the voltage feedback to a current feedback.
The current flowing through the common-emitter transistor is proportional to the input voltage. By using the current flowing through the common-emitter transistor as a feedback signal, the circuit becomes a current feedback amplifier, which allows for a faster response time and better bandwidth than a traditional voltage feedback amplifier.
A Class-AB amplifier output stage can be implemented using several different circuit configurations, each with its own advantages and disadvantages. Here is a summary of the main circuit configurations and their key characteristics:
- Quasi-complementary output stage: Uses both NPN and PNP transistors, which can reduce the distortion caused by the crossover region where the transistors switch on and off. The circuit complexity and cost of the output stage is higher than the single transistor based circuit like emitter follower but it has less distortion.
- Emitter follower output stage: Uses a single NPN transistor, where the emitter terminal is connected to the load. It has low output impedance and high current drive capability, which makes it ideal for driving loads such as speakers. However, the emitter follower output stage has a higher distortion due to the crossover distortion of single transistor.
- Double or Triple emitter output stage : Similar to the emitter follower output stage, but uses multiple NPN transistors connected in parallel. It reduces the crossover distortion caused by a single emitter follower output stage, but it increases the complexity and cost of the output stage.
- FET output stage: Uses a Field-Effect Transistor (FET) as the output stage. It has high input impedance, low output impedance, and low distortion. However, it also has lower voltage and current handling capability, and higher distortion at high frequencies compared to BJT based output stages.
- Complementary Feedback Pair (CFP): Uses a combination of NPN and PNP transistors in a cascode configuration. The CFP output stage is known for its low distortion and high power output. It is more complex and costly than the other output stages, but it offers the best overall performance.
What does this have to do with ChatGPT? Are you using it to generate all your posts in this thread?
Designing a Class-AB amplifier that meets the specific requirements of having a "warm, dynamic, musical, deep sound stage and good instrument separation" is a complex task that involves several stages of design. Here is a general approach that could be used to design such an amplifier:
It is advisable to consult with experts in the field, and to test and adjust the design through prototypes before finalizing the design.
- Input stage: A common-base (CB) or common-emitter (CE) configuration can be used for the input stage. CB and CE configurations are known for their high input impedance and good input voltage noise rejection. For the purpose of a warm and musical sound, a common-base stage would be a good option.
- Voltage gain stage: A Class-A or Class-AB voltage gain stage can be used. Class-A amplifiers are known for their low distortion and good linearity, but they have lower efficiency compared to Class-AB amplifiers. Class-AB amplifiers have higher efficiency, but they have higher distortion in the crossover region. For a warm and musical sound, a Class-A voltage gain stage would be a good option.
- Output stage: A Class-AB quasi-complementary output stage can be used. Quasi-complementary output stages are known for their low distortion and good linearity in the crossover region.
- Supply voltage: A desirable supply voltage could be around +/- 45V. This supply voltage would provide enough headroom to allow the amplifier to drive larger loads such as speakers with higher power.
It is advisable to consult with experts in the field, and to test and adjust the design through prototypes before finalizing the design.
I was going to post about this but you beat me to it.
Chatgpt is now answering most of my questions. Like I ask it to generate a tone control circuit for 500Hz it will spit it out. Ask it to calculate capasitor values. It does it. Ask it to design a class A preamp its does it.
It spits out schematics though I haven't figured out how to read ascii schematics.
But one thing that bugs the hell out of my is my inability to understand the concept of differential amplifiers.
I seem to be obsessed about it ever since I noticed that my Akai amp works by using two ICs
IC STK-3042/3062/ 3082 / that is connected to a IC STK-2250
Since then I keep thinking about why I cant design a differential setup where an opamp sends a differential signal to a chip amp like a LM3886 or a TDA7294.
One guy asked me why bother none of your inputs are differential. But none of my inputs are differential on my akai amp either and it still works really well.
Can somebody help me past this hurdle. By explaining how to or why to design such an amp.
Even Chatgpt could not help me with this.
Chatgpt is now answering most of my questions. Like I ask it to generate a tone control circuit for 500Hz it will spit it out. Ask it to calculate capasitor values. It does it. Ask it to design a class A preamp its does it.
It spits out schematics though I haven't figured out how to read ascii schematics.
But one thing that bugs the hell out of my is my inability to understand the concept of differential amplifiers.
I seem to be obsessed about it ever since I noticed that my Akai amp works by using two ICs
IC STK-3042/3062/ 3082 / that is connected to a IC STK-2250
Since then I keep thinking about why I cant design a differential setup where an opamp sends a differential signal to a chip amp like a LM3886 or a TDA7294.
One guy asked me why bother none of your inputs are differential. But none of my inputs are differential on my akai amp either and it still works really well.
Can somebody help me past this hurdle. By explaining how to or why to design such an amp.
Even Chatgpt could not help me with this.
For a Class-AB amplifier that is warm, dynamic, musical, has deep sound stage and good instrument separation, a bias servo circuit that incorporates a combination of features can be preferable.
One option would be to use a feedback control loop that compares the quiescent current in the output stage transistors to a reference current, this way you can ensure that the bias point remains stable over time.
Additionally, incorporating a temperature compensation feature in the bias servo circuit can help to maintain a stable bias point over a wide temperature range which can improve the linearity and distortion of the amplifier. This can be achieved by using a thermistor or a temperature-sensitive resistor in the bias servo circuit.
Using a low noise circuit in the bias servo circuit is also beneficial in order to minimize noise and interference in the audio signal, this can be achieved by using low-noise operational amplifiers or voltage regulators.
Furthermore, a high-gain circuit in the bias servo circuit allows for more precise control of the bias point, which can improve the linearity and distortion of the amplifier.
In summary, for a Class-AB amplifier that is warm, dynamic, musical, has deep sound stage, and good instrument separation, a bias servo circuit that incorporates a feedback control loop, temperature compensation, low noise circuit, and high-gain circuit can be a good option to consider. However, it is important to note that the final performance of the bias servo depends on the specific design, the choice of components and their specific implementation.
One option would be to use a feedback control loop that compares the quiescent current in the output stage transistors to a reference current, this way you can ensure that the bias point remains stable over time.
Additionally, incorporating a temperature compensation feature in the bias servo circuit can help to maintain a stable bias point over a wide temperature range which can improve the linearity and distortion of the amplifier. This can be achieved by using a thermistor or a temperature-sensitive resistor in the bias servo circuit.
Using a low noise circuit in the bias servo circuit is also beneficial in order to minimize noise and interference in the audio signal, this can be achieved by using low-noise operational amplifiers or voltage regulators.
Furthermore, a high-gain circuit in the bias servo circuit allows for more precise control of the bias point, which can improve the linearity and distortion of the amplifier.
In summary, for a Class-AB amplifier that is warm, dynamic, musical, has deep sound stage, and good instrument separation, a bias servo circuit that incorporates a feedback control loop, temperature compensation, low noise circuit, and high-gain circuit can be a good option to consider. However, it is important to note that the final performance of the bias servo depends on the specific design, the choice of components and their specific implementation.
When it doesnt know it doesnt know, it needs to feed more, will try coax it for you
GPT stands for "Generative Pre-training Transformer". It is the name of a large-scale language model developed by OpenAI. The model is trained using unsupervised learning techniques on a massive amount of text data and is capable of generating human-like text. The GPT models are trained to predict the next word in a sentence, based on the context of the previous words. This allows the model to generate text that is coherent and grammatically correct. GPT-3 is the latest version of GPT model, which is considered to be the most powerful language model till now.
STK (Sanyo Thermal Hybrid) chip amplifiers are a popular choice for audio applications because they are relatively inexpensive and easy to use. The STK series of amplifiers use a Darlington VBE multiplier circuit to generate a stable bias voltage for the base-emitter junction of the output stage transistors.
There are several reasons why the STK chip amplifiers use a Darlington VBE multiplier circuit:
There are several reasons why the STK chip amplifiers use a Darlington VBE multiplier circuit:
- High current gain: The Darlington pair in the VBE multiplier circuit can provide a high current gain, which can improve the precision of the bias point and reduce distortion.
- Temperature stability: Darlington VBE multiplier circuit can provide a stable bias point over a wide temperature range which can help to improve the linearity and distortion of the amplifier.
- Low noise: Darlington VBE multiplier circuit has a high input impedance and good input voltage noise rejection which makes it a good option for the input stage of an audio amplifier.
- Simplicity: Darlington VBE multiplier circuit is relatively simple to design and implement, which can help to reduce the cost of the amplifier.
Beware of ChatGPT shortcomings/mistakes.
I extensively tried it in several fields of scientific research of my daytime job where it fails in many areas outside of simple definitions.
Relevant to this forum: it failed big time at suggesting replacement latfets 👎👎👎
On the other hand it is quite good at generating programming code.
I extensively tried it in several fields of scientific research of my daytime job where it fails in many areas outside of simple definitions.
Relevant to this forum: it failed big time at suggesting replacement latfets 👎👎👎
On the other hand it is quite good at generating programming code.
You can't expect it to be perfect right now, it's recent. The outputs will be very dependent on the amount and quality of texts it has been fed. In addition, you sometimes need to nudge it in the right direction by repeatedly prompting it with more questions - code generation for a VST guitar distortion plugin was such an example.
OnAudio - you should use quote marks around text that you did not compose yourself.
This will be more important in the future obviously - source description. Always!!!!!
One should not have to ask as above! Grrr!
//
This will be more important in the future obviously - source description. Always!!!!!
One should not have to ask as above! Grrr!
//
Last edited:
Such software does not generate code, rather it searches and copies existing code.
You'd be surprised how many so-called 'Web Engineers' and other humans today do precisely that in commercial settings, so what's the point?
I am well aware of that. However, we should not attribute creativity to the software when it just copies,
or to humans either.
or to humans either.
A bit more than that. It can create working examples for user-specified routines and data with some variations if you repeat the question.