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What impedance do you wind up when you run a 4 ohm & 8 ohm speaker, in series and/or parallel? Does it make any difference which one is first in line?

I get confused about that stuff.


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Originally Posted by picker
What impedance do you wind up when you run a 4 ohm & 8 ohm speaker, in series and/or parallel? Does it make any difference which one is first in line?

I get confused about that stuff.

No difference in the order. If they are in series they simply add up, so it would be 12 Ohms. Parallel is some high order math, but I believe the easy version is to add the two & divide by two. So, around 6 Ohms in parallel. But it's been about 45 years since my electronics studies, so take the parallel portion of this with some amount of skepticism.


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Scott, this is where I get confused. I thought if you ran two 8 ohm speakers in series, you lowered the impedance to 4 ohm. Have I got that wrong?


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@ Picker, This article may be helpful. Considering the amp you are using will make a difference as well:

https://electrowebs.com/speaker-impedance-4-ohms-vs-8-ohms/

cool


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Here, this will make your brain hurt...

https://geoffthegreygeek.com/calculator-speakers-in-parallel/

Easiest way I know is to hook them up and put a meter on the leads.
In general, the output transformer on a tube amp is not as picky as a solid state amp can be. If the impedance is too low for a solid state amp it runs the risk of letting too much current flow and overheating.

At moderate volumes it should work fine on tube or solid state amps.


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Originally Posted by picker
Scott, this is where I get confused. I thought if you ran two 8 ohm speakers in series, you lowered the impedance to 4 ohm. Have I got that wrong?

Yeah, in series they add together. It's parallel where the math gets involved.


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Originally Posted by KuruPrionz
Easiest way I know is to hook them up and put a meter on the leads.

That gets you within the ballpark, maybe plus or minus 20%. An ohmmeter is just reading resistance. Impedance combines resistance, capacitance & inductance, but it turns out that impedance is sort of close to the resistance. Thing is, it changes with frequency. But, yeah, an ohmmeter will get you kind of close to the impedance of a speaker.


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Originally Posted by Scott Fraser
Originally Posted by KuruPrionz
Easiest way I know is to hook them up and put a meter on the leads.

That gets you within the ballpark, maybe plus or minus 20%. An ohmmeter is just reading resistance. Impedance combines resistance, capacitance & inductance, but it turns out that impedance is sort of close to the resistance. Thing is, it changes with frequency. But, yeah, an ohmmeter will get you kind of close to the impedance of a speaker.

Yep, completely true. If they are being consistent then impedance would be measured at 1000 hz. I don't know if that is true or not. In my experience, resistance is usually a bit lower than impedance.
As you say, it will get you in the ballpark. Usually that is good enough. Anything below 2 ohms or above 32 ohms could be questionable although there are amplifiers/transformers that can handle those loads too.
Most amps that can deal with 2 ohms will be for sound reinforcement or maybe for bass guitar. I can't think of the model but there is at least one vintage Fender tube amp that has a 32 ohm output on the transformer. Since their amps were copied so often there could be others.


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Most solid-state power amplifiers state a minimum impedance value, so if that value is 4 Ohms, your 8-Ohm speakers are above the minimum.

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C'mon, fellas. 2.667 ohms. 1/a + 1/b = 1/c
a and b are individual speaker impedence. c is total impedence.
Bet a dollar that it's not in series, as that would require soldering skills; almost nobody has that cable in their milk crate of cables. Picker might. But that's it. Series connect would be 12 ohms.


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