Amp RMS!!

[TheNewbie]

Im watching videos on it but ill def read some as well. Thanks for your help.

[audiofanaticz]

Alright thanks man, i hope my dc 2k will have 1600 watts rms of clean power. Appreciate your guys's help thanks again.

A DC, Sundown, Cactus sounds, American Bass, Audio Que, Digital Designs, Crescendo to name a few will do rated power and then some extra in most cases.

Now something like a Crunch, Power Acoustiks, Kole, Boss, Sony (more less the cheaper brands) will not do rated power, and are often rated in Peak Power. Any amp that advertises PEAK POWER on the box or on the amp, with no RMS Power listings usually wont do rated power.

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Some amps are CEA 2006 compliant which means these amps are tested to do rated power at 14.4 volts (for these amps you would want to use 14.4 volts to multiply the fuse rating by), See below for calculations!

However if your car does not charge at that 14.4 volts you wont get that power out of that amp, so you will want to use your voltage your car charges at.

To get a rough estimate before buying a amp to see what its rated power is you need to multiply the Fuses by voltage (either your cars voltage, or CEA 2006 Voltage which is 14.4)

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Usually its combined Fuse(s) X Voltage X .7 = rms power.

You Multiply by .7 to determine the amps efficiency at 1 ohm, which are normally around 70% efficient

So lets say your amp has a fuse rating of 300amps (determined by the amps manufacture).

Also lets say your car charges at a strong 13.8 volts with no voltage drop.

300 X 13.8 = 4140 watts, not including the amps efficiency

Now take the 4140 X .7 = 2898 Watts RMS

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So as above your posted 25+25+25+25 does not equal 1000watts. Unless your voltage was a constant 10volts in your vehicle.

so 100amps of fusing..

For 14.4 volts:

100 X 14.4 = 1440 watts

100 X 14.4 X .7 = 1008 watts rms

For 13.8 volts:

100 X 13.8 = 1380 watts

100 X 13.8 X .7 = 966 watts rms

For 12 volts:

100 X 12 = 1200 watts

100 X 12 X .7 = 840 watts rms

And last we will do 10volts since you said 25+25+25+25 = 1000 watts

100 X 10 = 1000 watts

100 X 10 X .7 = 700 watts rms, not 1000 after efficiency is calculated in.

Notice how the lower the cars voltage is, the less power the amp puts out?

[TheNewbie]

Wow that helped a ton man i get it now, i should most likely buy a stinger volt meter to see what im at so i could times it by that. ALthought it won't stay constant, this should just be with it running without a sub and amp right? Then take the average voltage i get? Seeing how the voltage in my truck will fluxuate. Also, that crunch amp so if it truely was even 840 for 12v after very little power to the sub it would have the clipping light showing going from green to red, if i was to keep it green all the time, it would barely push the sub, i guess that just teachs me not to buy a cheap amp. But how would i tell i could see how to do the rated rms now of the amp, but that doesnt mean it will nessesarily be clean wattage right?

[TheNewbie]

Also it could be that i needed more power in my truck, seeing how hard it hit varried on day to day, possibly could have been because of voltage drop, once i drive and let my alternator charge my battery it seems to hit alot harder. But the clipping still persists.

[TheNewbie]

Alright thanks man, i hope my dc 2k will have 1600 watts rms of clean power. Appreciate your guys's help thanks again.

A DC, Sundown, Cactus sounds, American Bass, Audio Que, Digital Designs, Crescendo to name a few will do rated power and then some extra in most cases.

Now something like a Crunch, Power Acoustiks, Kole, Boss, Sony (more less the cheaper brands) will not do rated power, and are often rated in Peak Power. Any amp that advertises PEAK POWER on the box or on the amp, with no RMS Power listings usually wont do rated power.

___________________________________________________________________________________________________

Some amps are CEA 2006 compliant which means these amps are tested to do rated power at 14.4 volts (for these amps you would want to use 14.4 volts to multiply the fuse rating by), See below for calculations!

However if your car does not charge at that 14.4 volts you wont get that power out of that amp, so you will want to use your voltage your car charges at.

To get a rough estimate before buying a amp to see what its rated power is you need to multiply the Fuses by voltage (either your cars voltage, or CEA 2006 Voltage which is 14.4)

___________________________________________________________________________________________________

Usually its combined Fuse(s) X Voltage X .7 = rms power.

You Multiply by .7 to determine the amps efficiency at 1 ohm, which are normally around 70% efficient

So lets say your amp has a fuse rating of 300amps (determined by the amps manufacture).

Also lets say your car charges at a strong 13.8 volts with no voltage drop.

300 X 13.8 = 4140 watts, not including the amps efficiency

Now take the 4140 X .7 = 2898 Watts RMS

___________________________________________________________________________________________________

So as above your posted 25+25+25+25 does not equal 1000watts. Unless your voltage was a constant 10volts in your vehicle.

so 100amps of fusing..

For 14.4 volts:

100 X 14.4 = 1440 watts

100 X 14.4 X .7 = 1008 watts rms

For 13.8 volts:

100 X 13.8 = 1380 watts

100 X 13.8 X .7 = 966 watts rms

For 12 volts:

100 X 12 = 1200 watts

100 X 12 X .7 = 840 watts rms

And last we will do 10volts since you said 25+25+25+25 = 1000 watts

100 X 10 = 1000 watts

100 X 10 X .7 = 700 watts rms, not 1000 after efficiency is calculated in.

Notice how the lower the cars voltage is, the less power the amp puts out?

Btw man thanks for the long reply, it really helped me understand exactly how everything is calculated. Very much appreciated man

[TheyDontWantMusic]

my 1500watt monoblock blew its 160amps worth of internal fusing, playing tones wired at 0.5ohm

amplifier is fine, just needs new fuses

fuses will handle significantly more than their rated current for short periods.

[audiofanaticz]

First off, voltage is almost never consistant, you will have voltage drop no matter what amp, the more power it makes the more voltage drop, which means you need stronger batteries or a high output alternator, big 3 wiring (info can be found in the electrical subforum how to do that -> http://www.stevemeadedesigns.com/board/topic/13280-how-to-do-the-big-3-tutorial/ )

As for the clip lights on an amp or a bass knob. They are never accurate. I think Steve Meade put it best by saying most people are idiots and ignore the actual meaning of the light and just think you got some cool light that blinks to the music.

To set your gains decently, but not properly you need a Digital Multi Meter (you can get cheap ones at wal-mart for 10-15 bucks), other wise you can get nicer brand name ones from Fluke, Extech, Craftsman.

***You will need one of these to test your vehicles voltage to set up your stinger volt meter properly if you buy one.***

with the multimeter you can use this chart below to find out how many A/C Volts you need to do said power at your ohm load:

The next best way to set the gain and you dont need a Digital Multimeter for is using an Oscilloscope:

This model here is a Oscilloscope with a Digital Multimeter (2 tools in 1) http://www.mobilesolutions-usa.com/smartparts/handhelddigital_1.htm

The Best way or as being said is using Steve Meades new device called the Distortion Detector DD-1

They are on PreSale right not for around $140 each. I know a few people have tried them, they look cool, but I cant honestly say if its as good as everyone claims until being able to use one myself. And you would still need to have a separate Digital multimeter for your other car audio needs.

http://www.stevemeadedesigns.com/board/topic/96947-new-product-distortion-detectornew-pics-page-22-video-update-page-26/

So in my own opinion for a person starting out needing tools it would be cheaper off buying the Oscope/multimeter for 250-350$ (depending where you buy).

VS

Buying the DD-1 Distortion Detector for $140, and then buying a quality Multimeter for 125-200$ for a combined total of 265-340$

[audiofanaticz]

my 1500watt monoblock blew its 160amps worth of internal fusing, playing tones wired at 0.5ohm

amplifier is fine, just needs new fuses

fuses will handle significantly more than their rated current for short periods.

thats because the amps are fused for their lowest impedance loud they are rated at.

if your amp needs 160amps of fusing to play at 1 ohm, its safe to say it will easily draw 220+ amps at .5 ohms if not more, as well as lowering its effiencey rating to around 40%-60% all depending on the amp of coarse.

However ATC style fuses normally dont handle too much more then what they are rated for compared to an anl fuse.

Also depending on company, some fuses (no matter what style) will last longer then another manufactures fuse of the same type.

So if your a MECA competitor trying to lower your fusing to get into a lower meca class, you may want to think of trying a few different brands of fuses, because you may be able to get more power and longer thru the same size fuse compared to another brand.

[TheNewbie]

Is there a way i vote you best answer of the year? Haha, really man i appreciate it greatly, one more question. Then most likely i'll know what is needed. Is there a way to tell the amount of Clean wattage an amp will push out without buying it just by it's specs. I know as you stated above you can use a smd dd1 or oscope but then you have to buy the amp first? I would think that the post before about the voltage ect is a way to find the rms you said, but then you still have clipping. So could the rms of the amp that i bought have still been dirty power. If so how can you tell if the rms that your calculating is clean or dirty power without buying the amp first. Im thinking you just have to go with the more known names DC sundown ect SO that you for sure get the rated wattage it says it pushs? Thanks for any other info you give me man really appreciate it.

[audiofanaticz]

There is no way to tell if the amp will be clean power at said voltages unless you buy it and test it with an oscope. A oscope will check for clipping. The SMD DD-1 not only checks for clipping but harmonic distortion which usually appears way before clipping, so the DD-1 has its advantages vs a oscope.

Generally speaking tho, amps power should be realitivly clean using the math formula above to get an estimate on their power.

Most quality amps are tested for Total Harmonic Distortion (THD) <0.1% @ 4 ohms.

However as you drop the impedance this distortion rate goes higher.

If you go ahead and look at the Crescendo 3kwp http://www.crescendoaudio.com/product.php?productid=17515

You will notice that at different impedance they have more THD.

You will also notice that they are have a much higher THD then many other quality amps at the same impedance, and some of these amps are all built at the same factory..

4 ohm power @ 13.8V @ .3% THD 855w

2 ohm power @ 13.8V @ .3% THD 1650w

1 ohm power @ 13.8V @ .3% THD 3,370w

.5 ohm power @ 13.8V @ .5% THD 4,030w

Efficiency @ 4 ohms 87% @ 60hz

So of coarse you can get much more power out of an amp if you crank the gain a tad higher then you should, but you result in having more distortion and clipping.

So for instance lets look at the old Sundown SAZ-3000 which is now discontinued, its the same PC-Board, built by the same Korean company called Zenon. However the Sundown amp had a headsink that has been revised many times for better cooling, and built with stronger parts (which is why this amp costed more then the Crescendo 3kwp, which is just the standard run of the mill type amp, with a generic heatsink).

http://sundownaudio.com/index.php/products/item/saz-3000d.html?category_id=12

So sundown rates their amp at:

4 ohm power @ 14.4V @ .1% THD 800w

Efficiency @ 4 ohms 86% @ 100hz

so with a bit of extra gain and a higher thd they get 55more watts from an amp.

But the thing to remember is, these amps are tested on a bench, usually with big power supplies to keep the voltage consistent. with a dummy load impedance that sees no impedance rise like a subwoofer would have.

So your results will have many more variables then what you read off the companies specs.

And most the mainstream companies that say they are CEA 2006 Compliant means the amp will make the claimed power you read on the box, but this is a out dated testing standard imo, but good for a novice guy buying a amp if he is smart enough to do the research before he buys.