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Noob question need some help!

199 Views 3 Replies 2 Participants Last post by bobknavs, Oct 18, 2019

vatzat

Discussion Starter · Oct 18, 2019

Hi all! I thought I would ask for some help on this possibly obvious answer to some but I am not completely sure about.

Here goes- I have 2 x 4 ohm speakers rated at 40w RMS. If I wore them in series I get an 8ohm load. Does this ALSO mean that the RMS for each speaker now changes from 40watts to somewhere around 20watts per speaker? Or does the speaker still handle 40 watts regardless of ohms?
Is it just the amount of watts the amplifier puts out that changes?

Thanks for the help/clarification!

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bobknavs

· #2 · Oct 18, 2019

vatzat said:
Hi all! I thought I would ask for some help on this possibly obvious answer to some but I am not completely sure about.

Here goes- I have 2 x 4 ohm speakers rated at 40w RMS. If I wore them in series I get an 8ohm load. Does this ALSO mean that the RMS for each speaker now changes from 40watts to somewhere around 20watts per speaker? Or does the speaker still handle 40 watts regardless of ohms?
Is it just the amount of watts the amplifier puts out that changes?

Thanks for the help/clarification!

Each speaker would still be rated at 40W, 80W for the pair.

The amplifier voltage would have to double to get there.

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vatzat

Discussion Starter · #3 · Oct 18, 2019

Thanks! So if my amp needs for example 10v 4ato hit 40watts a channel into 8 ohms, are you saying I would need to double my voltage to hit 80watts per channel to spread 40watts into each speaker?
Thanks

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bobknavs

· #4 · Oct 18, 2019

vatzat said:
Thanks! So if my amp needs for example 10v 4ato hit 40watts a channel into 8 ohms, are you saying I would need to double my voltage to hit 80watts per channel to spread 40watts into each speaker?
Thanks

No.

Power is proportional to voltage squared. Power is inversely proportional to resistance.

So, to get 40W from a 4 ohm load, you need 12.65V RMS. To get 80W (40W/speaker) with an 8 ohm load (two 40 Ohm speakers wired in series), you'd need 25.3V RMS.

If that language is meaningless to you, I don't know where to begin.

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