Ohmic Audio

9.1 Reading and Interpreting Audio Graphs

Tiny version

A graph is a picture of where the system gets too loud, too quiet, or too late.

Builder version

Use this page when you need to tell the difference between a real bass hump, a cancellation dip, a harmless slope, and a graph that only looks scary because of scale.

Deep version

The later sections keep the more technical graphs, but the first job is to learn the shapes before the jargon.

The frequency-response graph is the most useful picture in tuning because it turns "something sounds off" into something you can point at. The goal is not a perfectly pretty line. The goal is knowing which shape matters enough to fix.

Annotated frequency response graph showing a bass peak, crossover dip, and treble rolloff on a labeled frequency axis.
This is the beginner version of graph reading: find the obvious bump, find the obvious hole, and notice whether the top end falls away gently or sharply.

Translation box

  • Bump means too much level in one area.
  • Hole means something is cancelling or handing off badly.
  • Rolloff means the system fades away at one end.
  • Tilt means the whole line leans brighter or darker.

Common mistake

People often chase every tiny wiggle. Start with the big shapes first: the obvious hump, the obvious dip, or the obvious overall tilt.

One-minute checklist

  • Check the graph scale first.
  • Find the biggest bump.
  • Find the deepest dip.
  • Look for overall treble or bass tilt.

Why Scale Matters

The same curve can look calm or terrifying depending on the vertical range. That is why the first question is not "is this flat?" It is "what scale am I looking at?"

±30 dB scale Looks tame ±10 dB scale Looks meaningful ±5 dB scale Looks dramatic

Shape Words That Actually Help

Shape word What it looks like What it usually means
Bump Upward hill Too much energy in that range, often resonance or an over-strong target
Hole Sharp dip Cancellation, phase mismatch, or a bad crossover handoff
Rolloff Line falls away Natural limit of the driver or a filter doing its job
Ripple Repeated little waves Interference or reflections
Smooth zone Mostly even line A region that probably does not need heroic fixing

Practice Exercise

Look at the first graph again and answer these in order:

  1. Point to the bass hump.
  2. Point to the crossover dip.
  3. Point to the top-end rolloff.
  4. Decide which one looks big enough to fix first.

Worked example: if the graph shows a wide hump around 70 to 90 Hz and the sub sounds thick or trunk-heavy, start by checking sub level, crossover overlap, and placement before throwing EQ at every narrow wiggle.

Beyond Frequency Response

Other graph types still matter, but they are easier once the basic shape reading is clear.

Impedance Curves

Use impedance graphs to find resonance, enclosure tuning clues, and odd load behavior.

Waterfall / CSD Plots

Use waterfall plots to spot energy that hangs on too long after the main signal should have stopped.

Phase Response Graphs

Use phase graphs when the crossover handoff looks wrong even though the levels look close.

Group Delay Graphs

Use group delay when the bass feels slow or disconnected and you need to see whether timing smear is part of the story.