Checking the rms on an amp

[daveyboy1977]

Is there any way of checking how much rms the amp is doing without blowing my subs? It has 2 * 25A fuses in it. It says it puts out 350rms per channel, its a 4 channel amp, McHammer Mystic 4-Channel Car Hifi Amplifier 2700W System. I was wondering cause my speakers are 125rms and my subs are 200 rms, and I dont want to blow them.

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[phemps 10+ year member]

you would need an ammeter as well as a multimeter. With both of these its simple ohms law calculations to get your rms power

 

[jolly_26 10+ year member]

2 x 25A fuse = 50A max input current

50A x 15V(likely to be less than 15V) = 750 watts input, at the very most, before it blows it's fuses.

350 watts RMS x 4 Channels = 1400 watts RMS output

So with the manufacturers claims it is able to run at an efficiency rating of 187%.

It can't do that.

Assuming it happens to be a very efficient amp (lets say, 90%), which I guarantee it isn't, and that your electrical is giving it a constant 15V, which I also highly doubt, then it would output a maximum of 168 watts rms per channel. In the real world, I doubt it can dish out even that 125 watts rms that would blow your speakers to be honest.

What you should do instead of checking the rms is learn all about setting your gains, and read up on clipping to try and ensure that your amp isn't doing it; don't push your amp beyond what it can really do; you may need to borrow/buy an o scope.

Also, buy a better amp //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[daveyboy1977]

Thanks for the info, much appreciatted //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif. Will have a look at how to setup my gains. So my speakers and subs should be ok to put them into their own channel, cool //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif! Phemps, how would you check it with both of them?

 

[SourDeez 10+ year member]

Amps x volts = watts

 

[bigdwiz 10+ year member]

I recently added an SMD DD-1 to keep distortion measurements under 1%, but here is my video from a few months back with the other components...

Using a "Clamp" meter is good for a ballpark estimate, but the method I display is MUCH more accurate (also more involved, but you get what you pay for //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif )