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amp watts @ 8ohms vs 4ohms

Posted: Thu Apr 14, 2011 1:04 pm
by lumisonic
Given the same distortion percentages:
Why does an amp rated at 280 watts into 8 ohms not produce 560 watts at 4 ohms?
Mine states 450 watts at 4 ohms.

Re: amp watts @ 8ohms vs 4ohms

Posted: Thu Apr 14, 2011 1:21 pm
by Gregory East
Good question. I'm guessing it distorts more with all the extra current so to keep to the stated distortion the peak voltage comes down a little.

Re: amp watts @ 8ohms vs 4ohms

Posted: Thu Apr 14, 2011 1:37 pm
by Bill Fitzmaurice
lumisonic wrote:Given the same distortion percentages:
Why does an amp rated at 280 watts into 8 ohms not produce 560 watts at 4 ohms?
Maximum amplifier output power is not linear with respect to impedance load, due to power supply sag.

Re: amp watts @ 8ohms vs 4ohms

Posted: Fri Apr 15, 2011 3:14 pm
by Israel
not only power but cone control goes to hell and distortion is commonly 10x at 4 ohms remember treat your amps as well as u like 2 b treated :bash:

Re: amp watts @ 8ohms vs 4ohms

Posted: Wed May 11, 2011 1:00 am
by NCcrashman
Bill Fitzmaurice wrote:
lumisonic wrote:Given the same distortion percentages:
Why does an amp rated at 280 watts into 8 ohms not produce 560 watts at 4 ohms?
Maximum amplifier output power is not linear with respect to impedance load, due to power supply sag.
So, THAT'S why amp makers have been working to change p/s technology so fast! That makes complete, perfect sense!! You are THE audio God Bill. Damn, your good!!
-Patrick-

Re: amp watts @ 8ohms vs 4ohms

Posted: Wed May 11, 2011 1:03 am
by NCcrashman
Sorry folks. Just had one of those "Oh, I get it now!!!"moments...hahahaha

Re: amp watts @ 8ohms vs 4ohms

Posted: Wed May 11, 2011 6:09 am
by Israel
yep there was a time (long long time ago) when you can squeeze juice from a good amplifier well long after passing its manufacturer specs this was the time for receiving now is the time for giving giving up power, giving up sound quality giving up too much money for a vital piece of equipment that hesitates to work even near it featured specifications. Upss discharge life is letting me fall so often recently hahahahaha

Re: amp watts @ 8ohms vs 4ohms

Posted: Wed May 11, 2011 6:38 pm
by NCcrashman
Israel wrote:yep there was a time (long long time ago) when you can squeeze juice from a good amplifier well long after passing its manufacturer specs this was the time for receiving now is the time for giving giving up power, giving up sound quality giving up too much money for a vital piece of equipment that hesitates to work even near it featured specifications. Upss discharge life is letting me fall so often recently hahahahaha
Well put and correct. That's the "time" I am from running live sound. We used amp's with VU meter's that were crazy heavy and we used lot's of them. Most bigger venue's had 240v service with lots of amperage available for pa's. I guess some still do, but bars now either have "house" pa's or just standard 120v service. What's nice about 240 service is the amperage is cut in half so you can run double power amp duty for the price of 1. In other words, you can run 2 amplifiers at the price of 1.

-Patrick-