# Will very high speaker resistance ruin my amp?



## Dvic (Apr 17, 2013)

I am working on a project where 60 small 8 Ohm 0.1W speakers will be playing music from a live DJ. The majority of the sound will come from the pair of JBL 15" loudspeakers but i would like some of the sound to come through the small speakers. My concern is that if i run the amp with only a small group of speakers run in series the wattage from the amp will fry the speakers, and if i run the amp with too much resistance it will fry the amp. To achieve the 0.1 Watt amp output i would need 4000 Ohms of resistance on one channel. What to do? I have a 4 channel amp that puts out 50W at 8 Ohms per channel. Thanks for any comments/advice!


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## hjones4841 (Jan 21, 2009)

A series-parallel combination of the small speakers is your best bet. Not sure if you can wire it that way, tho.

You can find formulas for series and parallel connections on the web, but here is how it works:

Put two 8 ohm speakers in series = 16 ohms. Then put another pair in parallel with the first pair, and you are back at 8 ohms. Keep doing this series-parallel combo until all are wired that way.

BTW, the amp won't be "fried" with all in series, nor will the speakers be damaged. The problem is that your amp won't put out much power with that high of a load connected. It could be enough to drive the speakers, however, since you are not looking for much power to each anyway with their 0.1 watt rating.
But, don't put all in parallel since that would result in a very low combined impedance that your amp will have trouble driving - it could shutdown from overheating.


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## RBTO (Jan 27, 2010)

Is that 60 speakers per channel (left and right)?

You didn't mention how the 15 inch speakers would be wired. Assuming they are separate from the 60 small speakers, will they be fed from a separate output on the amp? If you plan on connecting them in parallel with the 60 speaker string on a single output, that also would bring your net amp load down below 8 Ohms which could be an issue for your amp.

The actual wattage to each of your small speakers depends on the volume adjustment of your music and the voltage at the amp output (assuming they are series-parallel connected as described previously). If you feed the entire string of 60 speakers let's say, 1 Watt, that will be evenly divided between the speakers so each will receive 1/60th of a watt. Your volume adjustment to the amp just needs to be set so the 0.1 Watt rating isn't exceeded by the loudest music and you're ok, but that means _all_ the small speakers will be contributing 6 Watts of sound (on peaks).


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