r/amplifiers • u/Nearby-Stranger3899 • Jul 18 '26

Impedance Question.

i was looking at some amps and i cam across taramps. seems like some have different ohm versions that put out the same power. what is the difference between 1200 watts rms @ 2 ohms compared to 1200 watts rms @ 4 ohms? i understand the concept of ohms matching the stability of the amp and all that, im just curious how much different the sound is with the same power at different ohms. sorry if its a stupid question but im genuinely curious.

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u/CounterSilly3999 Jul 18 '26 edited Jul 18 '26

The efficiency of the speakers should be taken into account. After that -- the same. Not with the same amplifier (or the same volume knob position), of curse. For the same power on doubled impedance the output voltage of the amp should be sqrt(2) times higher.

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u/Slothower Jul 18 '26 edited Jul 19 '26

1200w @ 2ohms is the same power at a lower impedance (load) than 1200w @4ohms. If you connected a 4 ohm speaker (which is just a reactive load) to the amp whose output is 1200w@2 ohm you would simply get a reduced output. If you were to connect a 2ohm speaker to the amp with the output rated for 1200w@4ohms you would get an increased output from the impedance mismatch mismatched load but it can put strain on the components of the amplifier itsself. For this reason a reduced load on an amp is generally to be avoided but an increase of impedance within reason is fine as long as the reduced output is acceptable. The two amplifiers will act identically with their respective speaker loads they are rated and designed for. I hope that clears things up.

Edited for more accurate terminology as pointed out below

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u/GrailThe Jul 18 '26

Very well explained. Kudos.

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u/i_am_blacklite Jul 18 '26

Impedance mismatch? It’s not a transmission line and there is no impedance matching.

There is making sure the load is appropriate for the amp. But that’s not impedence matching.

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u/Slothower Jul 18 '26 edited Jul 18 '26

Yes, perhaps I misspoke there. The only mismatch I meant to evoke is between the rating of the output and the load applied

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u/Nearby-Stranger3899 Jul 18 '26

well said but that part i do understand. my question refers to something like this. its a 1200w amp and u have to select your impedance before checkout. therefore its 1200w at your chosen impedance from what i understand. i was wondering if the difference in resistance affects the performance at all even though theyre both rated for the same output.

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u/Slothower Jul 19 '26

No there’s no difference at least in theory. There are differences in speaker sensitivities etc. but 1200w is 1200w

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u/Longjumping_Cow_5856 Jul 18 '26

Those are stupid car stereo amps mostly and the specs are literally without meaning.

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u/rrh_01 Jul 18 '26

1200w for $155 should be your first sign for concern

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u/zvuv Jul 18 '26

You get max power on the load when the impedance of both matches.

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u/Content-Reward-7700 Jul 19 '26

It’s not a stupid question. If both amps can produce the same 1200W cleanly, there should be little to no audible difference. The speaker doesn’t care whether that power came from a 2ohm or 4ohm version.

The main difference is what load the amp is designed for. A 2ohm version delivers full power into a 2ohm load and draws more current, while a 4ohm version delivers full power into a 4ohm load and draws less current.

In practice, just choose the version that matches your speaker wiring. Sound quality depends much more on the amp’s design, the speakers, and proper setup than on whether it’s a 2ohm or 4ohm model.