speaker wiring vs. handling capacity

[PeteMcK]

a series string of resistance drops voltage in proportion to the resistances....it doesn't matter whether it's the first resistance or the 100th...
so, if you have 4 equal resistances, you get equal voltage drop across, hence equal current., hence equal power...
400/4 = 100, sreten is right

"the first speaker would fry
when it sees a 400 watt RMS signal coming from the amp"
...it doesn't see the whole 400 watts.

Pete McK

[Crowe_Audio]

what happens at the limits though?

Imagine you got 100 little 5 watt speakers and wired them all in series. And cranked your 500 watt amp through them. I have a feeling the current would be way too much for each one, and it would be a fantastic sound+light show (and smell)....of course all it would take is for the first one to blow.

In parallel...the voltage would maybe be high enough to cause sparking?


Does someone have a 100 5 watt speakers kicking around?!

Trevor

[johninCR]

The answer is 400 watts either way. Each speaker is able to use 100 watts, which is the power used. In series you have to apply more pressure (voltage) to push the current through, but they all have the same amount of current run through them whether it's one driver or four in series for each to get 100 watts. The voltage drop across each driver times the current (amps) gives you the power (watts) used by each driver. Whether series or parallel, each driver needs the same amount of current to flow through it to get to 100 watts used, because the voltage drop across each is a constant at a given impedance.

The difference is what the amplifier will have to do. In parallel, it has to supply 4 times the current. That's where the light show will be, in the amp with 100 five watt drivers in parallel. In series the amp has to deliver 4 times the voltage.

It is my understanding that the voice coil of each driver will create some degree of phase shift in the signal passing through it. In addition, the voice coil inductance of each driver is multiplied by the number of drivers in a series configuration and divided by the number in parallel. I believe this makes parallel wiring more favorable without considering any amplifier issues, which may also be important.

Here's a question for the experts. Let's assume you have a line array and you need a specific combination of series and parallel. Does it make any difference how you do your series/parallel wiring and which order you connect the series wired drivers if there is phase shift created by each driver?

[barth2102]

Alain DuPont is the only fellow to agree with me on this so far. Perhaps I can ask him to elaborate on his reasoning.

I'm gonna prepare another cup of premium green tea now. Maybe I should spike it with some alcohol.

[pinkmouse]

Originally posted by Crowe_Audio
Imagine you got 100 little 5 watt speakers and wired them all in series. And cranked your 500 watt amp through them. I have a feeling the current would be way too much for each one, and it would be a fantastic sound+light show

Hmm. Have you never used series wired christmas lights?

edit: BTW, I'm with Sreten and his gang on this, if it wasn't obvious!

[dnsey]

There seems to be a lot of confusion here between the power which can be handled by a speaker and the current through the voicecoil.

I agree with Tweeker - each speaker can take the same amount of power as originally.
The first speaker in the series chain (whichever that is with an AC signal..!) will not be overloaded, as the (unipolar average) current through the entire chain is constant, and each unit will drop the same EMF across its coil. Hence the power input is evenly distributed beween all the drivers, so each can be driven to its maximum rating.

Until recent years, PA columns were often wired in a series-parallel arrangement, not only to achieve the desired acoustic characteristics, but so that sufficient power handling could be achieved using relatively 'low powered' drivers.

[sreten]

Originally posted by barth2102
Max, the question is more theory at this point. Let us assume that we have a nice PA amp that can deliver 400 watts RMS into a
32 ohm load with no problem. It can also deliver 400 watts RMS
into a 2 ohm load no problem. The question is not about amps or how much power it will take to drive either speaker wiring configuration. The question is regarding how much power the series wiring configuration will handle. We all know that 4 identical resistors wired in parallel will have 25% of the rated impedence of one resistor and a wattage handling capacity of 4 times the amount of one resistor. Everyone agrees with me here,
YES ?

4 - 8 ohm 100 watt resistors wired in parallel will have a 2 ohm load and handle 400 watts, correct ?

Now for the series configuration.

4 - 8 ohm 100 watt resistors wired in SERIES ( not series parallel ) will result in a 32 ohm load. But will it handle 400 watts?

As I mentioned before, I am old school. I built all my guitar cabinets when JBL used real ALNICO for their magnets. The wiring theory I obtained from JBL manuals of yesteryear. I still think that in the series configuration, the first speaker would fry
when it sees a 400 watt RMS signal coming from the amp, cause that speaker is rated for only 100 watts RMS.

So I agree with the Alain, the first reply to my post. Come on fellows , let's hear from you on this. It is not a difficult question, correct ?

Hi barth,

no its not a difficult question and you've recieved the
answer many times in various forms in this thread.

The simple answer to "4 - 8 ohm 100 watt resistors wired
in SERIES ( not series parallel ) will result in a 32 ohm load.
But will it handle 400 watts?" is YES.

The fact is you seem to have difficulty understanding this.
I suggest a book on basic electrical theory starting with ohms law.

V=I/R. Power (watts) = VxI or IxIxR or VxV/R.

The first speaker in the series chain sees the same current as the others.
Each speaker in the chain drops a 1/4 of the voltage, VxI =100watts.

Meanwhile the amplifier provides the current and all the voltage = 400w.

Carry on agreeing with Alain by all means, but this only means
that you are more interested in believing you are correct than
the actual facts of the matter - so why ask in the first place ?

/sreten.

[BWRX]

Perhaps it's easier to see if you break it down step by step.

One 8ohm driver can handle 100W. Power dissipation equals current squared multiplied by impedance, so P=I*I*R. This shows that the max. current the driver can handle is I=sqrt(P/R)=sqrt(100/8)=3.54A.

Four 8ohm drivers in parallel: each driver can handle 3.54A max so that means the amplifier would have to deliver 4*3.54A=14.14A of current. You can also view the four drivers in parallel as a 2ohm load, so P=I*I*R=14.14*14.14*2=400W.

Four 8ohm drivers in series: each driver can still handle 3.54A max, but they're all in series so the amplifier only has to deliver 3.54A of current. The four drivers in series gives you a 32ohm load, so P=I*I*R=3.54*3.54*32=400W.

Hopefully it's now very clear that both wiring configurations can handle 400W if the amplifier is capable enough!

[barth2102]

I submit that I think my primitive brain understands a bit more now. I think I see the light. I don't think Alain Dupont can come up with a reasonable explanation as he has not replied again. I am jumping ship and now agree that all wiring configurations will handle the same amount of power. Perhaps I'm just a salty old dog that doesn't want to change his ways.

The most recent post cleared things up better for my simple mind.

Thanks all my audio fanatic fellow. Sorry if I offended anybody.

Life is a learning experience and I hope to learn more. I actually do have some decent knowledge building speaker cabinets for guitar and know a bit about hi fi speaker building.

When I get back to the USA my next project will be transmission
line enclosures crossed over at 160 HZ to a 5" aluminum magnesium cone midrange crossed over to a ribbon tweeter ( yet
to be named ) at about 3K.

I'll be sure to read all the threads about TL theory and design, but I'm sure I'll have some questions for Mr. King and his tables.
I have actually built two pair of TL hifi cabinets way back in 1980.
They were classic design tapered line.

Thanks again.