Openai/6942bda8-3500-8009-863c-4337a422fc34

This conversation was exported from ChatGPT

gpt-5-2

User: what determines if BW stands for band width or butterworth in a EQ filter

what determines if BW stands for band width or butterworth in a EQ filter

Assistant: In EQ filters, BW can legitimately mean two different things, and what it stands for is determined by context: the type…

In EQ filters, BW can legitimately mean two different things, and what it stands for is determined by context: the type of filter being described and how the control behaves.

1. BW = Bandwidth

Most common in parametric EQs

What it means

Bandwidth describes how wide the affected frequency range is around the center frequency.

• Measured in octaves (e.g., 1.0 oct, 0.5 oct)
• Inversely related to Q - Wide BW = low Q - Narrow BW = high Q

How you can tell it’s Bandwidth

BW means Bandwidth when:

• The EQ is a bell / peaking filter
• You see controls like: - Freq / Gain / BW - or Freq / Gain / Q
• Changing BW makes the curve wider or narrower symmetrically

Example

BW = 1.0 octave

The EQ affects frequencies one octave wide centered on the selected frequency.

2. BW = Butterworth

Common in crossovers, HPF/LPF, and system processing

What it means

Butterworth refers to a filter alignment / response shape, not width.

Butterworth filters are:

• Maximally flat in the passband
• Smooth with no ripple
• Have a predictable phase response
• –3 dB at the cutoff frequency

How you can tell it’s Butterworth

BW means Butterworth when:

• The filter type is HPF or LPF
• You see options like: - BW, LR, BES, Cheby
• The slope is specified: - 12 dB/oct BW - 24 dB/oct BW

Example

24 dB/oct BW

This is a 4th-order Butterworth low-pass or high-pass filter.

3. How to tell which one it is (quick rule)

Ask these three questions:

| Question | If YES → | | ------------------------------------ | --------------------------------------- | | Is it a bell/peaking EQ? | BW = Bandwidth | | Is it HPF / LPF / crossover? | BW = Butterworth | | Does it change width or slope/shape? | Width = Bandwidth / Shape = Butterworth |

4. Digital mixer reality (like Behringer WING)

On mixers like the Behringer WING:

• Channel PEQ - BW = Bandwidth (bell filters)
• High-pass / Low-pass - Filter type is typically fixed (often Butterworth-style internally) - You usually don’t see “BW” labeled here unless choosing alignment

So if you see BW next to a bell EQ, it is Bandwidth, not Butterworth.

5. One-sentence takeaway

BW means Bandwidth when adjusting how wide an EQ bell is, and Butterworth when describing the response type of a high-pass or low-pass filter.

If you want, I can:

• Map this specifically to every EQ section on the WING
• Show BW vs Q mathematically
• Or provide training-course-ready wording for danatucker.com