Some guy at Carvin just told me...
 

that wiring two 4 ohm speakers in series would not produce an 8 ohm cab/load.

Am I a moron?

TIA

No, you are not. Wiring them in series get you 8, and parallel gets you 2.

No. Of course it won't be 8 ohms when measured by a VOM across the terminals.

<edit> OK, maybe Carvin guy not so dumb.

Wired in series, any break in the wiring shuts them all down. That's why we usually wire in parallel.

I am going to guess he misunderstood what you were saying. I have had several conversations with those guys and they have always been at least up to par if not great. Again, it's just a guess, but I think there's some sort of communication gap there.

That's why we have solder. ;)

My suspicion is that the other guy was probably thinking about daisy chaining multiple cabs, which does in fact put the speakers in parallel.

That's also why we wire speakers in parallel... :eyebrow:

MM

Quite a few 4x10 and 4x12 cabs are wired in series/parallel configuration from the factory. I'd be more worried about getting struck by lightning.

How often have you seen a speaker cab's wiring fail, or melt a voice coil? Sure wouldn't keep me up at night.

Interesting. Anybody got a link for some reasonably priced 16 ohm 10 inch speakers?

Again, thanks for the help.

Also, because amplifier outputs are primarily voltage sources, the variations in impedance among series-wired loudspeaker drivers will affect the signal that the other driver(s) receive. And vice-versa.

Explain this, please. If I'm running a series 8ohm and a parallel 8 ohm cab into a 4 ohm amp would this create problems for the amp?

Measured DC resistance does not equal nominal impedance.

There! See? :p

MM

An ohm meter simply measures DC resistance, while the impedance rating of a speaker also includes AC impedance created by the voice coil's inductance.

Basically, a speaker's resistance should always read somewhat lower than its nominal impedance because of this.

All of the mechanical attributes of the loudspeaker system--moving mass/inertia, spring action of the suspension, air loading and its variations due to the enclosure, driver resonance, etc.--also become part of the impedance.

Fair enough. A speaker is a motor, after all. The impedance vs frequency curves certainly don't look much like a plain old inductor.

This - in fact, nearly all 410s are wired series/parallel, and it never seems to be a problem for them...


- georgestrings

Probably. If that's the case, you need a special cable to daisy chain two cabs in series. I've made a couple of them.

What he said. Usually, an 8-ohm speaker impedance will read somewhere between 5 and 6 ohms on a DC ohmmeter.

You need to explain "4 ohm amp". If it is a SS head that says "4 ohm minimum" then two 4 ohm or a 4 ohm and 8 ohm cab in parallel will exceed the minimum load (4 ohm and 4 ohm= 2 ohms, 4 and 8=2.667 ohms). 8 and 8 in parallel = 4 ohm load and you are good, run them in series and the load becomes 16 ohms still fine but less power will be available from the amp. If it is a tube amp you should match the speaker cabs closely to the amps needs if at all possible.