sain settings....rms or total?

[orphe 10+ year member]

I got a question about setting the gain on an amp. Since I don’t have an o-scope I wanna set my gains on my hifonics 1500. Im gonna use 2 12’ kicker L7’s (2006) & set them up for 1 ohm.

My problem is I don’t know weather to use the amps RMS or total wattage when I do the math. So which one do I use? I’m stuck //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

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[dkguitarist 5,000+ posts]

rms values. always. but usually amps are either overrated or underrated. i thought you could turn the gains up until the reading on the dmm won't go any higher then turn it back down a lil and you'll be set..??

 

[FoxPro5 5,000+ posts]

Take the square root of the total RMS x resistance (ohms). So if your amp is rated for 1500 x 1 at 1 ohm, then set the DMM to approximately 38.7 volts AC. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[squeak9798 5,000+ posts]

i thought you could turn the gains up until the reading on the dmm won't go any higher then turn it back down a lil and you'll be set..??

No. The measure of RMS power simply the continuous power output at a certain distortion level (normally 1% THD). However, the DMM will continue to read higher voltages all the way up until you are at the maximum rail voltage, or the peak (and probably extremely distorted and/or clipped) voltage output the amplifier can produce. Meaning, the DMM can measure voltage, but not distortion levels....which is extremely important, and the entire point behind properly setting the gain.

Anyways....if that's the slightly overrated BX1500D, I'd probably use 1200w instead of the rated 1500w power figure. You want to use the value that the amplifier can realistically output.

 

[nVRuckus 5,000+ posts]

I prefer insane settings myself

 

[dkguitarist 5,000+ posts]

No. The measure of RMS power simply the continuous power output at a certain distortion level (normally 1% THD). However, the DMM will continue to read higher voltages all the way up until you are at the maximum rail voltage, or the peak (and probably extremely distorted and/or clipped) voltage output the amplifier can produce. Meaning, the DMM can measure voltage, but not distortion levels....which is extremely important, and the entire point behind properly setting the gain.

Anyways....if that's the slightly overrated BX1500D, I'd probably use 1200w instead of the rated 1500w power figure. You want to use the value that the amplifier can realistically output.

thanks for clearing that up. so that's y an o-scope would be much better as you can see the clipping..

 

[squeak9798 5,000+ posts]

thanks for clearing that up. so that's y an o-scope would be much better as you can see the clipping..

Yup.

Also, my comment that "You want to use the value that the amplifier can realistically output" also applies to underrated amplifiers...such as the newer RF Power amps and older Pioneer PRS amps, which are underrated by 100%+. In both cases you want to use the amount of power that the amplifier can realistically output.

 

[dkguitarist 5,000+ posts]

Yup.
Also, my comment that "You want to use the value that the amplifier can realistically output" also applies to underrated amplifiers...such as the newer RF Power amps and older Pioneer PRS amps, which are underrated by 100%+. In both cases you want to use the amount of power that the amplifier can realistically output.

so in that case all you can realistically do is go by the birth sheet? and if you don't have one, then what do you do? just guess?