[sdiy] Serge and multiples

[Grant Richter]

> Also not modern opamp like the TL07/08series can handle that amount of
> current. They have also an "output short-circuit protection". For protecting
> the standard opamp, an output resistor NOT needed. It is used for preventing
> oscillating cause by the capacitive load. As everybody knows, shielded cable
> (used for patch cords with jacks) has a much higher cable cap as unshielded
> cable (banana cords).
> 

Another reason for the resistor is to limit the current of static discharge
going INTO the output. The inductance and resistance of the resistor will do
a lot to limit a static spark into an output.

Buchla and Serge use and output structure where the current limiting
resistor is inside the op-amp feedback loop. This eliminates the voltage
drop of the resistor, but make the outputs "fight" each other when shorted
together.