[sdiy] Simple discrete Unity-Gain Follower ?

[Michael Buchstaller]

>That one will not really cut it for linear purposes, since there will a gray
>zone where the input is between the points where either of the upper and lower
>transistors is really biased.

Yes, i thought that this ultra-simple approach would not work as intended.

>Then naturally, you can always toss a feedback-loop onto it, but that brings
>a whole new realm of problems.

I do not want an output that easily overshoots or oscillates, or behaves
strange. So feedback shall be avoided, if possible.

>However, a properly designed amplifier may very well be op-amp free,
>no problems!

I never wanted to say that one could not design a very good amplifier without the
use of Opamps. But without diving too deep in theory, using OP´s makes life much
easier...
But i do not really like the idea of an all-transistor discrete circuit just to have
an Opamp follower at the output.

>The emitter-follower isn't that bad either, it have done marvels in the
>computer field (CDC 6600, 7600, 8600 and then the Cray-1 to mention a few).

Yes, but for audio i would prefer something else. Especially when i think about the low
load resistance that will be required to give low enough output impedance - i do not want
to hear this output stage over the power connections everywhere in my synth !


-Michael Buchstaller