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RE: I have some questions

A resistive attenuator with an input impedance of 10K has a worst case scenario output impedance of 2.5k ohm.

This is simple math.

With a 10K ohm attenuator adjusted so that the series resistance is 5k ohms and the shunt resistance is 5k ohms, the attenuation level is -6db and there are two paths to ground from the output point.

One path back through the series resistor to the source (with a low source impedance we can go ahead and call this ground and the math will not be off by very much at all)

The second path is across the shunt resistor to ground.

These paths are in parallel.

5k ohms in parallel with 5k ohms is 2500 ohm and that is the output impedance of the attenuator.

If the attenuator is re-adjusted in either direction the output impedance will go down.

Let's say the volume is turned down a little so the series resistance goes up and the shunt resistance goes down.

6k ohms for the series resistor and 4k ohms for the shunt.

6k in parallel with 4K = 2400 ohms.

Here's the equation for parallel resistors =(R1*R2)/(R1+R2)

So if we turn the volume up so the attenuation is less than -6db and our series resistance is 4 k ohm and the shunt resistance 6k ohm the output impedance is 2400 ohm.

Now let's make the resistors 2k and 8k (it doesn't matter which is series and which is shunt) 2k ohm in parallel with 8k ohm is 1600 ohms.

No magic, just simple math.

Tre'


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