amp impedances

[StickMe4myPaper 10+ year member]

maybe this is an obvious question i just dont know.. say an amp is 500w at 4 ohms 750 at 2 ohms, etc. is that amp putting out power at say 8 ohms? if so how much, around 250?

reason being is that i have crappy subs right now at about 100w a piece and i wanna upgrade my amp first. i wanna get one that will work great when i get better subs (600-800w) and wanna still be able to use that amp until then. Thanks!

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[BlactimusCrime 10+ year member]

yeah, thats true sometimes, but if you use a dmm to set gains you can dial in the wanted power pretty well even if you only need 300w at 4 ohms when the amp does 500 at 4

 

[Fiendstolemyamp 10+ year member]

is that amp putting out power at say 8 ohms? if so how much, around 250?

Yes & Yes

 

[BlactimusCrime 10+ year member]

Yes & Maybe

fix'd

 

[Moble Enclosurs 10+ year member]

yeah, thats true sometimes, but if you use a dmm to set gains you can dial in the wanted power pretty well even if you only need 300w at 4 ohms when the amp does 500 at 4

Yes, and along with that, it would be easier when using the DMM to convert to voltage. So, if you take the power formula, which is V^2/r. And work it backwards from power to voltage. So, a base at 500 W@4ohms. Take power(500)*4, which is 2000. Then take the recirical of a square which is a square root of 2000. This will give you volts. Which is 44.72 volts. Then you can dial in from there to figure for 8ohms power, by taking voltage^2/8, instead of 4. You will get your confirmed 250 watts. And the voltage would be converted from there again to tune to voltage with the DMM as voltage and power are not parallel in calculations. You should get a voltage of the same as with 4 ohms. Just at a different resistance level, to obtain the actual 250watts. If it does not reach the same voltage level, then the amplifier is not as efficient at 8 ohms as it is at 4.

 

[StickMe4myPaper 10+ year member]

alright thanks a lot guys

 

[Moble Enclosurs 10+ year member]

Your welcome! Good luck man