Speaker wattage and load

[RW James]

This is very confusing to me - so I probably won't explain it well. But I'm wondering how the power handling capabilities of speakers change when you change the load.

For instance, say you have two speakers 8 ohms and 50 watts - wired in series they become 16 ohms and ??? watts -- in parallel: 4 ohms and ??? watts.

I've seen 4x12 cabs with 30 watt speakers. I have to believe they can handle more than 30 watts, or even 60 watts - more likely 120 watts. How is this done?

And what happens if you have two speakers rated at 16 ohms each, but one rated at 75 watts and the second at 50 watts - wired in parallel they are 8 ohms, but how much power can they handle. I've always believed 50 watts. But if that were the case, then the 4x12 cab I described above could only handle 30 watts.

So-o-o... is there a rule similar to the one for calculating ohms that can be used for calculating speaker power handling capabilities?

 

[Christobevii3]

Re: Speaker wattage and load

30 watts x 4 = 120watts

You add the speaker power handling together to get the total. Also speakers that are built well can usually handle a little more power than they are rated for plus the enclosure they are in can help in handeling the mechanical movement ability.

Say you have 50 watts @ 8ohms
The amplifier will usually only put 25watts @ 16ohms
And at 4ohms will put out 100 watts

 

[muttonchopsrule]

Re: Speaker wattage and load

AFAIK, it's more the amp's output power that changes under different loads than it is the speaker's power handling, as he said above ^^^^.

if you've got different types of speakers with different power ratings being used together, then you should treat it as if you're using 2 (or 4, or however many) speakers that all have a power rating equal to the lowest one in there. for example, with your idea of using one 50 watt speaker and one 75 watt speaker, you should treat it like two 50 watt speakers, giving you a power handling of 100 watts. or if the speakers were 25 watts and 75 watts, you'd want to treat it like 50 watts.

 

[RW James]

Re: Speaker wattage and load

Thanks - that really helps a lot. So it really doesn't matter if the speakers are in series or parallel... interesting

 

[devastone]

Re: Speaker wattage and load

Say you have 50 watts @ 8ohms
The amplifier will usually only put 25watts @ 16ohms
And at 4ohms will put out 100 watts

This is true for SS amps, but for tube amps, that's what the impedance selector is for. It taps the output transformer at different points for different loads to keep the output consistent, meaning your 100W amp is putting out 100W into 4, 8, or 16 ohms provided the impedance selector is set to match the load.

Thanks - that really helps a lot. So it really doesn't matter if the speakers are in series or parallel... interesting

Nope, the power is equally dispersed either way.

 

[muttonchopsrule]

Re: Speaker wattage and load

no problem.

i remember hearing somewhere that the power is delivered equally between each speaker when more than one speaker is being used. so whether they're wired in series or parallel doesn't really affect it in that regard.

with that said, mixing different speakers can be a wonderful thing, such as the infamous vintage30/G12H30 combo :fing2: :fing2: :fing2:

 

[ErikH]

Re: Speaker wattage and load

Irregardless of using speakers of different wattage, such as the V30 and G12H30, the impedence of both should be the same. Don't use one that is 8 ohms and one that is 16 ohms.

In a 4x12, it is most common to wire up 4 X 16 ohm speakers in series/parallel. This will keep the impedance at 16 ohms for the entire cabinet.