What can you substitute a logarithmic potmeter with?

I would simply suggest taking a linear potmeter of approx a value 700% higher. Then connect a resistor of the original value +20% (approx) across linear pot middle and either side. This makes it working almost like the original logaritmic potmeter. If you want reverse log or dual log, then just connect the resistor to the other leg from middle, or halve the resistor value and connect both from the middle and to each side.

If you are unsure how it works, then a spreadsheet provides you with abilities to simulate how it will work.

Example of a "Linear Log Pot":

A project I started on needed a reverse log taper of 10 K.

This was nowhere to be found and I thought, lets cheat.

I started with spreadsheet and put in a few formulas for parallell connection of resistors.

I found that a 68K linear and a 12K resistor in parallell would give much the same performance curve as a logaritmic taper.

It gives approx the same resistance and approx the same voltage (if used as a voltage divider) as a Log and reverse log taper.