What Is a Decibel? dBFS, dBV, dBu and dBSPL Explained in Simple Terms

 ELI5 Decibels (dB):

1. Origin and Scale

• The Bel is a unit named after Alexander Graham Bell, but it's too big for everyday use.

• So we use 1/10th of a Bel = 1 decibel (dB).

• Think of dB as a way to measure change — like a ruler for comparing sound or signal levels, not an absolute amount.

How does Sound Work? Energy, Frequency & Vibration 

🔁 It's All About Ratios

• Decibels always compare one level to another. They're not fixed values — they're relative.

• We add suffixes to clarify what we’re comparing:

  • dBFS = compared to Full Scale (digital max)

  • dBV = compared to 1 Volt

  • dBu = compared to 0.775 Volts

  • dBSPL = compared to the quietest sound humans can hear

The Cycle of Sound: 6 Ways to Measure Audio Waveforms

💡 Power vs. Voltage: Two dB Worlds

POWER (Watts, like amps or light bulbs)

• +3dB = double the power

• Ex: Going from 100W to 200W is a 3dB boost.

• Surprising fact: Doubling your sound system power only gives you 3dB more.

VOLTAGE (Signals, like audio levels)

• +6dB = double the voltage

• Ex: Going from 1 Volt to 2 Volts = +6dB

• Why? Because Power = Voltage², so doubling volts gives 4x the power (which = +6dB)

⭐️ Start by downloading all of my FREE Music Production Guides ⭐️ It took me years to learn this stuff!

🎛 What About Faders?

• A fader is a ratio tool — it controls how much of the input passes through.

• 0dB = no change

• -6dB = cuts signal to half the voltage

• -∞dB = total silence (no signal passes)

That’s why fader marks are often spaced in 6dB steps — it matches how our ears respond to volume changes.

🎧 Quick Summary: The dB Suffixes

🌀 Why dB Is Logarithmic (Not Linear)

• dB steps go: 1, 2, 4, 8, 16... (not 1, 2, 3, 4)

• This matches how our ears naturally hear — we’re better at detecting ratios than tiny differences.

• It also compresses massive differences into manageable numbers (e.g., 80dB = 10,000:1 ratio!)

⭐️ Download my FREE Home Studio Setup Guide ⭐️ 

Decibels (dB) – Simple Cheat Sheet 

What Is a Decibel (dB)?

- A decibel (dB) is a way to measure change or ratio, not an absolute number.

- It's 1/10th of a Bel, named after Alexander Graham Bell.

- Used to compare levels, like sound or voltage, with a reference point.

dB for Power vs Voltage

- Power (Watts): +3dB = double the power (e.g., 100W to 200W = +3dB)

- Voltage (or Pressure): +6dB = double the voltage (e.g., 1V to 2V = +6dB)

dB Suffixes & Their Meaning

- dBFS (Full Scale): max level in digital (0dBFS = clipping point)

- dBV: compared to 1 Volt (0dBV = 1V)

- dBu: compared to 0.775V (0dBu = 0.775V)

- dBSPL: compares sound to human hearing threshold

Why Use Decibels?

- The dB scale is logarithmic (1, 2, 4, 8...), not linear.

- It matches how humans perceive loudness.

- Lets us represent big differences with small numbers (e.g., 80dB = 10,000:1).

Faders and dB

- A fader shows the output-to-input ratio:

- 0dB = no change

- -6dB = half the voltage

- -∞ dB = no signal (silence)

⭐️ Download my Free Magic Compressor Settings Guide ⭐️ 

⭐️ Download my Free 10 Characteristic of a Sound Wave Guide ⭐️

#protools #daw #homestudio #recordingschool #recording #musicproduction 

Also read: 

How to Start Your Own Online Business Teaching Music
 

Hey, I'm Futch - Music Production Coach and Ableton Certified Trainer

Learn how to make your first song and beat in Ableton Live with my

FREE 90-minute Ableton Live course

I've been teaching audio engineering and music production for 35 years.⭐️ 

Check out my new online music production program: Music Production Ninja...