There's some 2-transistor buffers in that thread:
http://www.diyaudio.com/forums/solid-state/64617-single-bjt-buffer-schema-kindly-requested.html
Basic Buffers
The Transistor Amplifier
Opamp Alternatives
Rod Elliot discusses current source for emitter circuit (I guess that would be the second transistor?) but then skips over that in favor of a 3-transistor circuit.
http://www.diyaudio.com/forums/solid-state/64617-single-bjt-buffer-schema-kindly-requested.html
Basic Buffers
The Transistor Amplifier
Opamp Alternatives
Rod Elliot discusses current source for emitter circuit (I guess that would be the second transistor?) but then skips over that in favor of a 3-transistor circuit.
And here's more 3 transistor buffer:
Building a buffered Gainclone chip amp.
Nick has much interesting experiments and comments on the discrete buffers.
It is interesting to note that instead of changing the transistor to get a different HFE, it should be possible to change a resistor value to have much the same effect, without changing the model of transistor at all. I don't know the details on that. I believe that because of current, the resistors must be recalculated to fit your target power supply voltage. I don't know how to do the recalculation. I also can't find a simulator file for 1, 2, or 3 transistor buffer. So, although the prospect certainly isn't doable to me, if your maths are a lot better, then you could probably do it.
Building a buffered Gainclone chip amp.
Nick has much interesting experiments and comments on the discrete buffers.
It is interesting to note that instead of changing the transistor to get a different HFE, it should be possible to change a resistor value to have much the same effect, without changing the model of transistor at all. I don't know the details on that. I believe that because of current, the resistors must be recalculated to fit your target power supply voltage. I don't know how to do the recalculation. I also can't find a simulator file for 1, 2, or 3 transistor buffer. So, although the prospect certainly isn't doable to me, if your maths are a lot better, then you could probably do it.
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Or, try a different model of car chip. Given a different internal topology, your input caps might not fight. That should probably be tested.
Some other options may include: TDA7292, TDA7265B, TDA7265, TDA7269, TDA7576, TDA1521Q, TDA1554Q, TDA8561Q, TDA1560Q, TDA1562Q, TDA1554, TDA1554q, TDA1557, TDA1557Q, TDA7386_07, TDA8563AQ, TDA7377, TDA7560_05, TDA1563Q, TDA1516BQ, TDA7389, TDA8564Q, TDA7375A, PA7375, NTE7163, LA4625, LA4628, LA47202P, LA4905, TDA2009
Some other options may include: TDA7292, TDA7265B, TDA7265, TDA7269, TDA7576, TDA1521Q, TDA1554Q, TDA8561Q, TDA1560Q, TDA1562Q, TDA1554, TDA1554q, TDA1557, TDA1557Q, TDA7386_07, TDA8563AQ, TDA7377, TDA7560_05, TDA1563Q, TDA1516BQ, TDA7389, TDA8564Q, TDA7375A, PA7375, NTE7163, LA4625, LA4628, LA47202P, LA4905, TDA2009
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Hello Daniel,
Thank you very much for your great support, I'm testing the On Semiconductor/Sanyo LA4450 and I'm impressed very good, it has a very good sound quality for an IC, and seems to don't have problems with the TDA2822M, and it's mounted on a breadboard and without any input buffer, it's input has very high impedance and it's ground referenced.
PS: How the V+/2 offset is set at the output off the LA4450 IC, thru the feedback resistors using a current source like in the TDA2822M? Do you still working on TDA7297 buffer?
Best regards,
Daniel Almeida
Thank you very much for your great support, I'm testing the On Semiconductor/Sanyo LA4450 and I'm impressed very good, it has a very good sound quality for an IC, and seems to don't have problems with the TDA2822M, and it's mounted on a breadboard and without any input buffer, it's input has very high impedance and it's ground referenced.
PS: How the V+/2 offset is set at the output off the LA4450 IC, thru the feedback resistors using a current source like in the TDA2822M? Do you still working on TDA7297 buffer?
Best regards,
Daniel Almeida
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