4 Ohm vs 8 Ohm Speakers

Why impedance matters

Impedance is the load a speaker presents to the amplifier. It decides how much current the amplifier must deliver for a given power: a 4 ohm load draws roughly twice the current of an 8 ohm load at the same voltage. Neither is "better" — they suit different systems.

4 ohm: the car audio standard

Vehicle electrical systems run at low voltage, so car audio standardised on 4 ohm speakers to draw useful power from head-unit and amplifier outputs. Nearly every specified model in the GRANVOZ car audio families is a 4 ohm design — the TSP-166 tweeter, the MD-65S23-06 midrange and the MC-80S23-03 coaxial all publish a 4 ohm nominal impedance. Dual voice coil subwoofers in the catalogue publish configurations such as 4+4 ohm and 2+2 ohm, which let the installer wire the two coils in series or parallel to present the load the amplifier prefers.

8 ohm: the PA and home standard

PA and installed systems run longer cable lengths and often parallel several speakers on one amplifier channel, so 8 ohm is the working standard — the PA models in this catalogue, such as the PA-0718 woofer (8 ohm in its published description), follow it. Some midrange models in the catalogue publish a choice — the MD-10S30-04 and MD-65S23-05 tables list 4/6/8 ohm nominal impedance — which means the model is produced in impedance variants: ask the sales team to confirm the variant you are ordering, because the variant is part of the order specification, not a setting.

The rules that keep systems safe

• Never present an amplifier with a load below its rated minimum — parallel wiring divides impedance fast.
• Two 8 ohm speakers in parallel make a 4 ohm load; two 4 ohm speakers make 2 ohm, which many amplifiers cannot drive.
• Series wiring adds impedances and shares power; dual voice coil models exist precisely to give these options on one cone.
• Match the speaker's impedance variant at order time — it is printed in the model's published specification where one exists.