jgorman01 wrote:

>  Just a quick example. In order to achieve a flat passband of 3 kHz
>  you may really need an amplifier whose bandwidth is 10 or even 20
>  kHz. To achieve this, you probably can't use just one single stage of
>  audio amplification with a simple emitter bypass electrolytic
>  capacitor, you'll need several stages of Class A (both DC and AC bias
>  stabilized) thereby raising the costs significantly. Precision
>  components will be used rather than run of the mill 10% tolerance. It
>  all adds up both in cost and performance.
>
>  Jim WA0LYK


I am afraid we are aiming at different solutions.

I wouldn't use bipolars, I would use op amps. Well used, you would incur 
in less than
0.1 % distortion,  and I am afraid it is much more than what it would 
deliver. I have
achieved in practice distortions in the order of 0.05% or less for pro 
audio designs.

With op amps, you just decide the corner frequencies, and the gain you 
want. Of course,
you must consider the open loop gain and the unity gain frequency. The 
rest is choosing
the right resistor values. The rest of the engineering needed is already 
included inside
the chip.

And unless you are working with balanced, matched amplifiers, a fraction 
of a dB goes
nowhere. So, 10% resistors are perfectly adequate.

I would avoid aluminum foil electrolytics. Those are the quickest aging 
and most prone
to fail components in a properly done design.


73 de Jose, CO2JA

















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