Speaker Ohms

Paul Norman · From: Washington, North Carolina, USA

If I replace an 8 ohm speaker with a 4 ohm
speaker will I need a resistor.
Will the amp be too strong for the speaker?
Or will it increase the watt power of the
amp. It is a 65Watt with a 12- 8 Ohm.

Jim Sliff · From: Lawndale California, USA

A resistor will not help you, unless it's HUGE - has to be to handle the power. Plus a resistor does not react like a speaker coil. It's a no-go.

Using a 4-ohm speaker depends on the amp. Many tube amps can handle a 100% mismatch in impedance, but with a loss of power (yes - even lowering the impedance *decreases* power in this case) and sometimes a negative affect on tone. Others can't take it at all. Solid state amps also vary - many are made to adapt to different impedances; others are "locked in".

It completely depends on the amp you have - but based on the power level, my guess is it's solid state and not adaptable to different impedances, or a tube amp that will prbably not sound as good with the mismatch. I'd normally suggest not doing it.

Also, the impedance has zero to do with the amp being "to strong" for the speaker. Impedance and power handling are unrelated. Speakers are rated for maximum power levels, a factor that has nothing to do with the impedance - many manufacturers make the same speaker - say one that handles 75 watts - in 4, 8 and 16 ohm versions. They do that to allow them to be used in different amps.

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