## Bass Boost Calculator

This page has a few calculators that will help you to pick optimal
component values for the PPA’s bass boost circuit.

These calculators are based on the formulas derived in this
Head-Fi thread.

### Definitions

**ƒc** — The frequency at which the boost is +3 dB;
the corner frequency of the filter. Below this frequency, the PPA
bass boost increases by 6 dB each time you divide the frequency
in half, up to the point where the shelving action kicks in.

**ƒs** — The frequency at which the boost curve is
3 dB below the maximum boost value; the shelving frequency of
the filter.

**ƒo** — Frequency where the gain is half the total
boost. Used when boost is 6 dB or less, since ƒc and ƒs
cross each other at this point.

### I Know What Resistor Values I Will Use, What C7 Will Give
Me the ƒc I Want?

This calculator will help you pick a C7 value given the ƒc and the
R3, R4 and R7 values. The answer will not be rounded off to a standard
value, since different capacitor lines have different standard values.

You may use power notation for the resistors: 120K, 1.0M, etc. The
power suffix can be uppercase or lowercase.

The formula for this is:

### Given All the Component Values, What Filter
Characteristics Will I Get?

The formulæ for this are: