aight thanks!

 

To produce 400 Watts output @ 12V and the amp is 50% eifficient, 66.7 amps would be needed. If this same amp was in someone's system and they were listening to music (or whatever you kids think is music today) and the person was an abusive listener the average demand would be 32 amps.
A normal listener would drive the system to draw 13.4 amps.

The difference between the two profiles is the amount of clipping the listener will drive the system to. Abusive listeners will use 50% of the amplifier power with music average over time. A normal listener will use 20% of the amplifier power over time with music. Amplifiers which are 50% efficient need to draw twice the power rating to produce the rated power output, the rest is wasted as heat.

The formula is Power / Voltage = Current.

 

OK, I just did my math wrong..haha..

shouldn't it be
(watts/voltage)/effeciency = amperes? I think I did (watts*effeciency)/voltage=amperes....

BTW:
Class a/b amps are typically 50-60% effecient
Class D amps are typically 70-80% effecient

that's just a generality though... some could be lower, some higher

 

Class D amplifiers are generally used in subwoofer applications. Although their design offers greater efficiency than A/B amplifiers, they are also driven into higher levels of clipping than other amps due to our lack of sensitivity to low frequency. Even "golden eared" audiophiles will commonly drive their subwoofer amplifiers to 10 - 15% distortion. Obviously, by using Class D you're still ahead in the efficiency game, but it real life Class D is on par with A/B amps in efficency. If you were using an A/B amp on your subwoofers the efficiency would be far worse, but you would have higher damping factor generally speaking. With few exceptions, Class D offers higher efficiency than A/B, but almost no control due to the switching design.

 

That's why it's good to use an o-scope to find the max unclipped gain level, then set it to your likings under that setting...

 

There is a couple other things here to. Alot of the issues that people run into also is that they will run there amp wide open. (gain all the way up). Alot of people think the gain is a volume ****. The problem with that is the gain is to level match the headunits output and the amps input. When the gain is wide open and you are already running a high output deck you are clipping your amp before you ever really get started on the output. This causes the amp to work harder and causes more distortion. Therefore pulling more current from the electrical system.
Another issue is people running there amp at a lower ohm load then what is recommded cause it "makes more power that way". That is not true. 90% of the time you are not making more power, you are just increasing the distortion rate of the amp. The speakers are now taking all the abuse. Your speakers wont like it, your amp wont like it, the charging system wont like it.

The key to any system is the charging system. The system can only do what it can with the right backing. Putting a cap or anything like that in a lacking charging system will usually only put more of a strain on the system. They are more like a band aid. They will help in some situations, but wont fix a bad cut. LOL.

 

Using an O scope to set gains is not a bad idea at all assuming you own one and know how to use one. For the other 99% of the human race that listens to music in their cars this practice would have no impact.
Also, using the Oscope to set gains has nothing to do with what the end user will do with it. I don't know anyone who would be happy with the output of a zero-clipped system. Everyone drives their system into clipping (even you), some more than others. Clipping is a way of life today as many recordings have such a low crest factor that they are clipped before the CD (or itunes downloaded) is even played.
Using and O scope or multimeter to set gains is a great way to manage clipping but you want to allow for some overlap to allow for moderate clipping (what all humans do) and avoid severe clipping where things start burning.
A great method to set gains if you don't have an Oscope is illustrated here: http://mobile.jlaudio.com/support_pages.php?page_id=143

 

Look for MEAN GREEN alternators...they make bad a** off road ones that last forever

 

I need help... My stock stereo is hooked up to my 2 10" JBL subs with 1200wat amp. all installed by cartoys. When am sitting it sounds fine and when i start moving the bass gets a lot louder and doesnt sound too good. but if am sitting and hit the gas in park or neutral the bass doesnt change so i thought it might be a power problem but am not sure now. I need help on what is going on. Does Scion stock stereo have a road noise inside the stereo or is it the battery, alternator, not enough power or what???? Someone help....

 

hey man, which year is your car? cuz i know for 06' have a diff radio that has an ASL level. its pretty much used in the way so that the volume goes up as the car moves to compensate for "wind" noise on the highway and such. if ur car is an 06' and up, turn off your ASL, and you should be good.

 

Same thing happen to me yesterday, car completly shut down in the middle of the road. i had subwoofers turned off thou but i was driving in traffic with the ac on. I couldnt get my car to turn on for an hour figuring out wtf happen. First i thought it was main fuse blown, but it was fine. I took a look at it today to see wut went wrong with my multimeter.

The problem wouldnt repeat but i turned of ALL my accories including ac and lights. Car wanted to stall a few times and got this low voltage reading I also heard the altinator making clicks. After a few seconds voltage went up to normal sorry i dont have AMP clamps for the multimeter for more testing.
What should i do?? buy used eom alternator or buy a higher amp alternator? I have a lot of leds/neons everywhere, navi, subs, gauges, radar, etc.