/diy/ - Do It Yourself

>>1158295
Your circuit has pretty high output impedance (roughly Rc) and that together with various capacitances forms a low-pass filter, killing your gain at higher frequencies. Since the output is not matched, your cable can be a significant capacitive load, too.

Typical solutions are tuned output, much smaller resistors and using other circuit topologies not having the same problems. Pic related is a 27MHz amplifier using the first option.

You dimension the base voltage divider so that the base voltage is emitter voltage + 0.7V in idle. The current through the divider is usually set to 5 to 10 times the idle base current (so that the base current won't upset the divider too much).

>>1158516
He's right, though. You can think it this way: your battery with a center 6V tap (and speaker connected to it) would allow +/-6V across the speaker (12V-6V vs. 0V-6V). Using two amplifiers, each having an output voltage range of 0-12V would allow +/-12V across the speaker (12V-0V vs 0V-12V).
https://en.wikipedia.org/wiki/Bridge-tied_load