Input Impedances - Make them Your Own

A project log for Muffsy Phono Preamp PP-2

An Improved AudioKarma CNC Phono Stage

skrodahlskrodahl 03/27/2015 at 14:440 Comments

Rest assured, my phono stage build is coming along nicely. There'll be more about that in future log entries. For now, let's play around with the circuit a bit.

The Muffsy Phono Preamp comes with a set of preselectable input impedances. There is nothing stopping you from changing them, but what to?

To help you decide the best set of resistors, use this Excel impedance calculator. Simply fill in different resistor values and see the impedances change.

NOTE: The industry standard input impedance is 47 kOhm. I would recommend that at least one of your settings matches that, or has a value that's reasonably close to 47 kOhm.

You may notice that there are a few more values in this table (which uses the default Muffsy PP-2 values) than what I have presented earlier. That's because I chose to ignore some of the impedances that are almost equal.

Here they are again, for your reference:

You may also wonder why these values still differ a bit. Well, you see, I did some rounding to make them look nice. Yup, I took that liberty...