Ohmic Audio

🔰 BEGINNER LEVEL: Frequency Response Basics

What is Frequency Response?

Frequency response shows how loud a system plays each frequency.

Labeled frequency response graph comparing a smooth target curve to a peaky real-world response across bass, midrange, and treble
A frequency-response graph is just a map of loudness versus frequency. Smoother curves tend to sound more balanced, while big peaks and dips usually translate into obvious tonal problems.

Ideal response: Flat line (all frequencies equal volume) Real systems: Have peaks and dips

Why flat response matters: - Music sounds balanced - Natural tonality - No frequency emphasis/missing - What artist intended

Reading frequency response graphs:

X-axis: Frequency (Hz) - logarithmic scale - 20 Hz (deep bass) to 20,000 Hz (high treble)

Y-axis: Level (dB) - 0 dB = reference - +6 dB = twice as loud - -6 dB = half as loud

Common problems visible: - Peak at 50 Hz: Too much bass - Dip at 3 kHz: Vocals sound recessed - Rolloff above 10 kHz: Lacks sparkle

What Are Crossovers?

Crossover = Filter that sends specific frequencies to specific speakers.

Why needed:

Tweeters can't play bass - they'll break! Subwoofers can't play highs - they're too slow!

Simple signal-split diagram showing a full-range input dividing into low frequencies for a subwoofer, mid frequencies for a woofer or midbass, and high frequencies for a tweeter, with basic crossover regions labeled.
A crossover is just routing. It keeps bass away from tweeters, keeps treble away from the subwoofer, and lets each driver work in the band it can reproduce cleanly.

Types of crossovers:

High-pass filter (HPF): - Passes high frequencies - Blocks low frequencies - Used for tweeters and midrange

Low-pass filter (LPF): - Passes low frequencies - Blocks high frequencies - Used for subwoofers

Band-pass filter: - Passes middle frequencies - Blocks highs and lows - Used for dedicated midrange

Crossover Points

Where to cross over?

Rule of thumb: - Subwoofer: 80 Hz (typical for music) - Midbass to midrange: 250-500 Hz - Midrange to tweeter: 2,500-4,000 Hz

Too low crossover: - Speaker tries to play below its range - Distortion - Possible damage

Too high crossover: - Gap in frequency coverage - Thin, unnatural sound

Start with manufacturer recommendations!

Crossover Slope

Slope = How quickly filter attenuates

Comparison chart showing 6, 12, 24, and 36 dB per octave crossover slopes so the difference between gentle and steep rolloff is easy to see at a glance.
Slope changes how fast the filter moves out of the way. Gentle slopes let more overlap through, while steep slopes separate drivers faster and protect them more aggressively.

Common slopes: - 6 dB/octave: Gentle, smooth transition - 12 dB/octave: Most common, good balance - 24 dB/octave: Steep, clean separation - 36 dB/octave: Very steep, maximum protection

Steeper slope: - Better speaker protection - Cleaner separation - Less overlap - But can cause phase issues

Gentler slope: - More natural sound - Better integration - More overlap (power handling concern)