Capsule polarization resistor/capacitor values.
- Thread starter vmanj
- Start date
Help Support GroupDIY Audio Forum:
I think I have had a misconception somewhere. I always thought that you did not want a capacitor after the bias voltage resistor, and you wanted that resistor as large a value as practical because the large value of the resistor was what simulated the "constant charge" part of the approximations that allowed a condenser microphone to work (V=Q/C, so dv=Q/dC, with the assumption that Q is nearly constant in the frequency range of interest).
Although now that I think about it a little, I think you could have a low impedance connection to one side of the capacitor (i.e. capsule) as long as the other side was high impedance. Maybe even preferred so that you don't have both sides of a single diaphragm capsule swinging in opposite directions.
But that would apply for the diaphragm bias resistor for a dual diaphragm, would it not? You would want a low impedance to the backplate, but high impedance feeding charge to each diaphragm, and high impedance at the buffer that the diaphragms feed. I think, but maybe I'm missing something there.
There are two basic connections for bias, one is applying the bias to one electrode whilst the other is connected to the high-Z head amp, the other is to apply bias via a very high resistance to an electrode, the same electrode being connected via a capacitor to the head amp.
Of course the latter is a less quiet solution, since it limits the actual resistive load; however it is often favoured on SDC because of practical reasons, essentially mechanical.
Of course the latter is a less quiet solution, since it limits the actual resistive load; however it is often favoured on SDC because of practical reasons, essentially mechanical.
