When you’re building or buying speakers, you’ll often come across technical terms like frequency response, resonance (Fs), and impedance (Ohms).

If you’re new to audio, these can feel confusing — but once you understand the basics, choosing the right driver becomes much easier.

This guide breaks down frequency parameters and impedance parameters in a simple, practical way.

 

What is Frequency in Audio?

Frequency refers to how low or high a sound is, measured in Hertz (Hz).

• Low frequencies (20Hz – 200Hz) → Bass (deep sounds like drums)
• Mid frequencies (200Hz – 2kHz) → Vocals & instruments
• High frequencies (2kHz – 20kHz) → Treble (clarity, detail)
• Humans can hear roughly 20Hz to 20,000Hz (20kHz)

Frequency Parameters in Speaker Drivers

1. Frequency Response

This tells you the range of sound a speaker can reproduce.

Example:

• 50Hz – 20kHz → Covers bass to treble
• 80Hz – 5kHz → Midrange focused

✔️ Why it matters:
Wider range = more complete sound

2. Resonant Frequency (Fs)

Fs (Resonant Frequency) is the point where the speaker naturally vibrates the most.

• Lower Fs = better bass capability
• Higher Fs = suited for mids or highs

Example:

• Woofer: ~40Hz
• Tweeter: ~1,500Hz+

✔️ Tip:
For deep bass, always choose drivers with low Fs

3. Sensitivity (dB)

• Measured in dB (decibels)
• Shows how loud a speaker gets with 1 watt power

Example:

• 85dB → Needs more power
• 92dB → Louder with less power

✔️ Higher sensitivity = more efficient speaker

4. Crossover Frequency (Concept)

Different drivers handle different frequencies:

• Woofer → Bass
• Midrange → Vocals
• Tweeter → Highs

A crossover splits the signal so each driver plays what it’s best at.

What is Impedance?

Impedance is the resistance a speaker gives to the amplifier’s current.
It is measured in Ohms (Ω).

Common values:

• 4Ω
• 6Ω
• 8Ω

Key Things to Understand

1. Not a Fixed Value

A speaker is not always exactly 4Ω or 8Ω.
- Impedance changes with frequency, forming what’s called an impedance curve.

Series vs Parallel (Basic Idea)

When you connect multiple speakers or drivers together, the way you wire them - series or parallel - directly affects both impedance and output (sensitivity/loudness).

Series Connection

How it works:
Speakers are connected end-to-end (one after another).

Impedance in Series

• Impedance adds up

Example:

• Two 8Ω speakers → 16Ω total

Sensitivity (What Happens?)

• Power is divided between speakers
• Each speaker plays quieter

👉 Result:

• Combined output is almost similar to a single speaker, sometimes slightly higher (~+1 to +2 dB in real-world)

Example

• One speaker sensitivity = 88 dB (1W/1m)
• Two speakers in series:

👉 Total sensitivity ≈ 89–90 dB

✔️ Gain is small because each speaker gets less power

 

Parallel Connection

Connection: All positives together, all negatives together.

Impedance

• Decreases
• Example:
  • Two 8Ω speakers → 4Ω total

Sensitivity (What Happens?)

• Each speaker gets full voltage
• More total acoustic output

👉 Result:

• Noticeable increase in loudness

Example

• One speaker sensitivity = 88 dB (1W/1m)
• Two speakers in parallel:

👉 Total sensitivity ≈ 91 dB

✔️ Around +3 dB increase (doubling of acoustic output)

 

Key Insight (Important for Beginners)

• +3 dB = Double sound output (perceived improvement)
• Parallel wiring is commonly used when higher output is needed
• Series wiring is used when higher impedance is required