A Bit Of Info About Max Power Amp Ratings

[jaxx]

Put simply RMS is 'usable power' and is the exact figure on what your amp produces/sub requires to work at the optimum.

The peak power figure is true but also total crap!

It works like this.

Max Power of an amp is the amount of power that and amp will produce under perfect conditions AND with an unlimited power supply, i wont go into unlimited power as its a form of Quantum Physics!

In standard knowledged and rule of thumb it is taken into account that an amplifier is 50% efficient. THERE IS NO SUCH THING AS AN EFFICIENT AMPLIFIER! And 50% is the general figure taken for efficiency for amps. The other 50% is lost through heat and the components working to amp the signal.

So for aruments sake we have an amp rated at 600watts max output power.

So if the amp has an efficiency of 50% this must mean that another 50% is to count for the losses.

Theoretically the amp actually produces 1200watts! (600w max power, 600w for losses)

Now some simple maths:-

Current = Power/Voltage

Lets say our car is running and the alternator is running at a perfect and constant 14.4volts.

Add this to the equation and you get

Current = 1200/14.4 = which is 83.3 Amps

Now look at the fuse in the side of the amp. For example it will be 40 amps.

So theres somat not right there! As that would have blown up long ago!

So reverse the equation to

Power = Voltage x Current

So:-

Power = 14.4 x 40 = 576 Watts

Now take into account the efficiency

so 50% of 576 = 288watts

Your 600watt amp actually produces 228watts!

at 12 volts (engine off) it only produces 240watts!

(these are all example figures)

[Nizan]

you da man rob

I just happern to be in the market for this sort of stuff at the moment.

Cheers for the post mate

Niz

[Chyownster]

Yeah, it is important for people to know this so people dont have barbacues in their boot!

[n00bie]

Yeh he's right :

So how many Watts have you got in your car ?

LOL What you have 1000W MAN? ...

I mean I have a pure amp indoors dedicated to driving 2 subs.

Amp is rated at 150W per channel and I can only ever get it to 5 mark(say 75W per channel) on the dial.

At "6" Doors and windows shake more violently, things start getting scarey and to top it the next door neighbours loft conversion starts rattlin' (Hmmmm I thinks me had better rig it up again ;)

This wattage nonesense is just to sell some gear.

Always read the RMS @ the specificied resistance me says.

n b

[jaxx]

EXACTLY noobie thats a very good point!

companys will slap 10MILLION WATTS MAX POWER on an amp cos bumcases will think its mega powerful and buy it!

not true!

ive made you guys a present!

download the excel file and tap your own amp ratings into the red bits, the green bits will show the actual!

[jaxx]

whoop hang on did somat wrong!

[knightrider]

where is it man? lol jk

[Moffmo]

yeah where is it lol!

Good point Noobie - iv seen amps that are 1500w Peak! i was like

Then i saw the rms - a WHOPPING 150w RMS!

Woot??

Cheers

[jaxx]

hold on lads workin on it!

excel at work seems nacked! ill do it at home!

[vmail]

what if you have 3 fuses

1 x 60 Amp on the cable

2 x 20 Amp on the Amp

[Moffmo]

jaxx gimme formulas and ill make it for impatient ones!

[jaxx]

the fuse on the power cable means naff all

the two fuses on the amp make a total of 40amps

moffmo, just make up the spreadsheet from the formulas on the first post, its only simple stuff

[Moffmo]

ok working on it....

What do i use for power?

[vmail]

cheers, so if I use 2 x 30 Amps, will I bugger the Amp?

[jaxx]

yes you will vmail

fuse ratings are there for a reason

[Moffmo]

jaxx - answer above post please! :)

Cheers

matt

[jaxx]

oh

err.................you need the complete power for both actual and losses

[jaxx]

well........

the user can input max power then use formuals to double it

[Moffmo]

DONE, Where shall i email it to??

[jaxx]

me

[Moffmo]

i have to be gold... However iv just noticed something...My formula doesnt use the max power....

It is totally depandant on fuse!

Cheers

Matt

[jaxx]

doh

no worries mate ill sort it later

[Moffmo]

ok... its just you work out 83.3 current - and then you dont even use it becuase of fuse so whats the pont in working it out?

Cheers

matt

[jaxx]

its to demonstrate that the amp wont produce 1200watts on the cars system, thats all. unless you had 83amps and being as the amp is only rated at 40 then you reverse engineer it

i think ive missed somat aswell??

will have to review it later

[Moffmo]

i think you have m8! LOL

You dont use anything with 83.3 figure, due to fuse limiting it at 40...

But fuses blow when 83.3 is going through a 40 fuse so you must have to work out where it goes down

ie. 83.3 / 2 to not blow fuse lol...