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-   -   oh my Ohms are tired (http://www.talkbass.com/forum/f15/oh-my-ohms-tired-1040053/)

 muddpuddle 12-22-2013 12:38 PM

oh my Ohms are tired

Can anybody help me understand amps and ohms

I have an old peavy head that's rated 210 amps at 2 ohms. What would be the result of playing through a single 8 ohm speaker

 B-string 12-22-2013 12:42 PM

I'm sure you meant 210 WATTS not amps. Being a SS amp, use of an 8 ohm speaker would just mean it will produce much less wattage from the amp.

The "Stickies" are chocked full of ohms/wattage info.

 beans-on-toast 12-22-2013 12:46 PM

Oh my is right! That would be 88,200 watts. I figure that you'd probably blow your speaker.

First step in answering your question is to know what model amp you have.

 swamp_bass 12-22-2013 12:50 PM

The general rule is that an amp's output will be half at double the speaker impedance. Many amps aren't quite linear that way, but it's a good general way to approximate.

So 210 Watts into 2 ohms becomes:
* 105 Watts into 4 ohms,
* 60 Watts into 8 ohms.

Many amps deviate from that general rule. Often amps that are "stable to 2 ohms" use active current limiting at 2 ohms that limits power to approximately the same output as 4 ohms. If that's the case, then your output into 8 ohms would be more like 100 watts.

So somewhere between 50 and 100 is the ballpark.

 nashvillebill 12-22-2013 02:15 PM

That series of Peavey power amps is rated:

210 watts into 2 ohms at 1% THD
140 watts into 4 ohms
80 watts into 8 ohms

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