BJT Amplifiers

[Born2bwire]

So you're saying there's no rhyme or reason to audio engineering?

No, but people can get away with a lot in audio which is why there can be a lot of snake oil attached to it. It's also why a lot of poor designs can get out into the marketplace. I've seen my fair share with headphone amplifiers and cables. Some amplifier designs have bordered onto being outright dangerous and some cable designs I've seen have poor ideas about shielding. The same basics that apply to RF or microwave engineering apply to the ELF ranges as well. However, the consequences become greatly diminished due to the relative electrical sizes of these devices. So while it may not make a real difference, it would not be very good teaching if they did not try to enforce proper design rules.

Well, we got to ask the teacher a lot of questions about this project. He basically said. "It should just be in the ball park." In other words, as long as our input impedance was something less than 500 ohms and our output impedance was less than 80 ohms, we would be good. I was going to shoot for exact impedance matching, but I guess I don't have to anymore.

Thanks for the help so far guys, in some ways this is more educational than the class has been

Yes, for audio frequencies it really doesn't matter too much. It will matter when you start going into RF frequencies and above which is why I think it is a good idea that they still try to encourage you to impedence match.

 

[Howard]

No, but people can get away with a lot in audio which is why there can be a lot of snake oil attached to it. It's also why a lot of poor designs can get out into the marketplace. I've seen my fair share with headphone amplifiers and cables. Some amplifier designs have bordered onto being outright dangerous and some cable designs I've seen have poor ideas about shielding. The same basics that apply to RF or microwave engineering apply to the ELF ranges as well. However, the consequences become greatly diminished due to the relative electrical sizes of these devices. So while it may not make a real difference, it would not be very good teaching if they did not try to enforce proper design rules.

Yes, lots of garbage, but the same can be said for any commercial application of science.

Safety is not at stake here, but audio fidelity is, if you make maximum power transfer (in itself rarely required in audio) a goal. If your point is that audio fidelity is not at all a factor, then why mention audio in the problem in the first place? Lots of things besides line-level audio need amplification.

 

[esun]

No, but people can get away with a lot in audio which is why there can be a lot of snake oil attached to it. It's also why a lot of poor designs can get out into the marketplace. I've seen my fair share with headphone amplifiers and cables. Some amplifier designs have bordered onto being outright dangerous and some cable designs I've seen have poor ideas about shielding. The same basics that apply to RF or microwave engineering apply to the ELF ranges as well. However, the consequences become greatly diminished due to the relative electrical sizes of these devices. So while it may not make a real difference, it would not be very good teaching if they did not try to enforce proper design rules.



Yes, for audio frequencies it really doesn't matter too much. It will matter when you start going into RF frequencies and above which is why I think it is a good idea that they still try to encourage you to impedence match.

Proper design rules for audio are different than proper design rules for RF, and it would be not very good teaching to teach students to use RF design rules in audio systems.