Ohms / watts question

RDT · #1 03-22-2010, 10:29 AM

I have a 5.34 ohm cabinet (6 x 175watt-8ohm speakers wired series/parallel) rated at 1050 watts.

If my amp output is 1200 watts @ 4ohms, or 600 watts @ 8ohms; what would the output be going into 5.34ohms?

I know I'm not getting the max output, of course. I'm just curious what the wattage output is given the resistance.

ericw · #2 03-22-2010, 10:51 AM

I think you can just interpolate that... 999 watts. Someone correct me.

billfitzmaurice · #3 03-22-2010, 11:54 AM

Quote:

Originally Posted by RDT

If my amp output is 1200 watts @ 4ohms, or 600 watts @ 8ohms; what would the output be going into 5.34ohms?

It would be moot, as your 175 watt speakers probably can't take more than 100 watts each best case before farting out anyway.

RDT · #4 03-22-2010, 12:08 PM

Quote:

Originally Posted by billfitzmaurice

It would be moot, as your 175 watt speakers probably can't take more than 100 watts each best case before farting out anyway.

???????

So, you're telling me that my 6x10 cab won't handle anything more than 1/12th the power of a 1200watt head!!!!

Rick Auricchio · #5 03-22-2010, 12:35 PM

No, six speakers at 100 watts each is 600 watts. When it farts out, that's the practical limit of the cabinet.

Most cabs fart out long before reaching max power.

scottbass · #6 03-22-2010, 01:04 PM

Theoretically, your amp would put out 900 watts at 5.33 ohms, assuming Ohm's Law relationship of DC output to DC resistance (not impedance), etc. But in reality, it's what Bill & Rick said: the speakers will handle whatever they will handle, not what they are rated. The rest of the amp's (theoretical) output is what we enthusiastically refer to as "headroom"! But your amp probably won't put out 900 watts of usable power, anyway, depending on what frequency & THD% was used to come up with its rating.

The real truth: don't clip the amp & don't fart the speakers and you will be OK as long as the heat buildup doesn't get you. If you can't get enough volume without clipping the amp, you need a bigger amp. If you can't get enough volume without farting the speakers, you need speakers that will handle more power - or more speakers.

Calaverasgrande · #7 03-22-2010, 01:30 PM

Its also gonna depend on how you wired it.
When you have speakers wired in parallel (for example 8&8 for four ohms) they share the watts evenly, so you get a higher power handling. When you wire the same speakers in series (8 & 8 for 16 ohms) each speaker carries all the current, so you get only as much power handling as the individual speaker has. think of it like plumbing. Two 1 inch pipes in parallel carry more water (watter?) at any point along the line than two 1 inch pipes end to end.
So if you wired it as 3 sets of 2 speakers in series, than put those 3 sets in parallel you would only have the watt handling of 3 speakers added together.
There is also that your multimeter will read DC resistance as opposed to AC impedance, which is higher. So if you are getting 5.34 ohms from math its probably about right, if you are getting 5.34 from a meter you probably are closer to 6 ohms or 8 ohms.

RDT · #8 03-22-2010, 04:14 PM

Here is how my speakers are wired. And here is where I got my info.

After wiring my speakers this way, my volt/ohm meter reads a touch over 5 (I have an analog meter).

I just ordered a Genz Benz ShuttleMax 12.0 and want to ensure, if nothing else in my own mind, I'm not gonna smoke or blow either.

http://www.colomar.com/Shavano/spkr_wiring.html

States:

2 sets of 3 speakers in parallel, with those 2 sets in series:

* For 4 ohm speakers, you get a 2.67 ohm load.
WARNING:Power amp must be able to drive a 2 ohm load

* For 6 ohm speakers, you get an 4 ohm load.

* For 8 ohm speakers, you get a 5.34 ohm load.

* For 16 ohm speakers, you get a 10.66 ohm load.