I know this question was answered in another thread but thought it needed its own place here for future discussion.

Thanks to Jeff24 for asking the question.

Jeff24:
“Barry: can the PreAmp Boost have the Tight/All Frequencies mod done? Typically I’d be looking for a 10n or 220n capacitor; what needs to be modded, or does it let all frequencies through?”

Barry:
“You would need to reduce R1 to 10M (down from 22M) for all suggestions below:

Preamp Boost assuming (R1 ≈ 10 MΩ) – C1 High-Pass Options

Treble-focused – 47 nF (159 Hz)
Strong bass roll-off; tightens low-E strings, very bright tone.

Tight lows – 100 nF (150 Hz)
Noticeable bass reduction; low-E fundamental trimmed.

Moderate trim – 220 nF (73 Hz)
Slightly tighter low end; low-E lightly affected.

Subtle trim – 470 nF (34 Hz)
Minimal low-frequency reduction; almost full guitar lows pass.

Notes:

Use film-type capacitors (polypropylene or polyester) for best tone.

Smaller capacitance → higher cutoff → more low-frequency roll-off.

Larger capacitance → lower cutoff → fuller bass response.”