Ohm

[ModedLS]

hey guys, might be a dumb question, but im new to the whole science of audio here. i was wondering what the difference was between 2, 4, and 8 ohms. when a deck or amp says it is a certain ohm. thanks

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[alphakenny1 10+ year member]

http://www.bcae1.com/

 

[thch 10+ year member]

ohm is a measure of electrical resistance. it relates to ohms law -- V = I*R, and power law P = I*V.

if you want to make an amp for a high impedance speaker, you'd have to design around high voltages and low current. for a low impedance speaker, you need high currents and low voltages. there are a set of advantages and disadvantages to each.

in a car, you've got 12V. so low impedance speakers make sense. and aftermarket amps follow suite (as they need to work with the existing 4ohm speakers).

in other applications you've got easy access to higher voltages, and could choose a higher impedance speaker.

common misconceptions:

'ohms' is a measure of resistance or impedance. it is a property of the speaker, not the amp. the amp will (usually) be able to power different impedances with a different amount of power. if you try to attach too low of an impedance (to get more power then advertised) you run the risk of damaging the amp.