[CompDude]

OK I have this one question that's been wanting to be answered for a long time. If I or someone else wanted to put a new (and good) car stereo system into his/her car, how do you know if the amps will work with the speakers and/or subs. Like say you wanted to power a 1000W Sub, how much power (wattage) would the amp need. Or could someone explain this to me.

 

[CompDude]

anyone??

 

[d00dz]

For replacing the head unit in a car stereo, pretty much just replacing the stock one and putting in a new one with the same connectiong usually works...
Usually the car speakers are ratted more then what the stock head unit outputs.

Most better end head units come with 50w x 4 output, and that's more then enough for driving the stock speakers....you can then always replace the speakers for much better sound...

There aren't too many speaker resistance options in cars, they are usually rated I believe at 8 ohm, but i'm not 100% positive.

However usually the rated watts is more of a gimmic and sales pitch then real improvment over loudness. The most important consideration is just making sure that the head unit is compatable with the resistance of the speakers. (But like is said that is not difficult to do with car audio).

As with the subwoofer, the 1000w is usually Peak ratings and not RMS (to get RMS values just divide the peak by root 2). To power the sub you will need to get a seperate amplifier. There are sub amps that you can buy or stereo amps. The only difference is that the sub has a mono output, but you can usually bridge the stereo amp into mono output. These amps are usually 4 ohm as are most subwoofers.

So if you got a sub that's advertised 1000w, you can get a amplifier upto 1000w mono, or less. Just connect it from the "line-out/subwoofer out" from the head unit.

If you have more then one sub and connect them series you get 8 ohms and then you amp rating will not be 1000w any more as there is more resistance. But anybody hardly ever uses maximum rated values as at those volumes serious hearing damage is imminent.

You can save some cash and buy an amp in the 400w range and it will be more then enough.

Well i hope everything i said here was right, but don't quote me on it.

 

[Okkler]

All that wattage is going to totally blow up your headphones.

 

[llmobll]

I just wanted to add that the power ratings on most car stuff is bogus. They almost always list power ratings in Peak power. Unless it states RMS power you need to divide by 2 to get the RMS value. So when shopping for stuff, a quality amp will usually states its output in RMS values. Stuff you find on ebay "claiming" 1000w usually only 500w. This is a trick they use to lure inexperienced buyers to buy lower rated equipement.

 

[slipkid]

Hey Comp

Most car spealers are 4 ohm. Subs are a different story, they can get very complicated as far as ohms go. Same with the amp wattage for subs. Head units come in all prices and quality (sound & options), but as already posted, 50X4 is the max. As for your last question, there are just too many variables for a short answer or even a long one! Would be the same as asking "what's the best headphone rig setup for me?"
Try Elite Car Audio. They are set up much the same as this Head-Fi. Plenty of stickies and many friendly people to ask.
One word of caution, use the search before asking any questions! Most of the newbie questions and answers have been posted in a sticky!! or just wear a flame suit it you don't want to reaserch.

Slipkid

 

[slick]

just be careful with ratings is the main thing. you asked, how do you power a 1000watt sub. you need to know if that rating is the RMS or PEAK rating the sub can handle. some companies confuse consumers by advertising 1000watt capable subs, when its really 200watts RMS (the continuous power) and 1000watts PEAK (the amount of power it can handle if the wattage spiked for a couple seconds).
generally, speakers are 4 ohms. subs come in too many forms.
generalization is hard, if you have specifics, its easier to answer (and i bet you will understand better that way).

example. my subwoofer has an RMS rating of 1000watts and peak of 2000watts. its a dual 4 ohm voice coil sub, so it has two 4 ohm coils. i can wire it in parallel, which would be the amps + to voice coil #1 + to voice coil #2
+ and the amps - to voice coil #1 - to voice coil #2 -. that would decrease the impedance and yeild a 2 ohm load from the amp.
wiring it in series, amps + to voice coil #1 +, then voice coil #1 - to voice coil #2 +, then voice coil #2 - to amps -, will increase the impedance and yeild a 8 ohm load from the amp.
knowing that lets you know what kind of amp you should get. since its hard to find amps that make decent power at 8 ohms, i would look for an amp that made the power i need (roughly 1000watts RMS) at a 2 ohm load. my amp makes 800watts at 2 ohms, good enough.

if you thought that was confusing, try adding another sub to the equation

 

[CompDude]

so basically if i had/wanted a sub that was 2000W Peak and 750 W RMS and was 4ohm + 4 ohm (which i think is like ur dual 4 ohm voice coil sub) then i could/should get an amp that's rated at 750/800 W RMS at 2ohm's if i wanted it in parallel?

 

[scott916]

you're really in the wrong forum. you should go post at elitecaraudio or sounddomain before the mods just close the thread anyway.

 

[hypophysis]

You should never mind the nominal maximum power input for subwoofers.
If it is a lower end subwoofer, the number will be definitely fantasy (like those 2500W+ ghettoblasters). If it is a real good subwoofer it should be really heavy duty if it could take 1 KW of electric energy.
But this has no impact on your amp. If your amp can deliver 200 W of clean power without clipping, you should do fine and get deaf if you turn the volume to max. Most cars have a nice bass boost due to compression chamber characteristics (a car has a lot fewer cubic meters volume than a average living room).
I think headphone HiFi is one of the last resorts of consumer audio that has never taken part in the Watt madness. So don't let you be blended by all these numbers with car audio neither.

 

[Jam_Master_J]

Yeah, don't play the wattage game. Remember too, the difference between 100 watts and 400 watts is only 6dB so buying a lot of power for a car doesn't make sense.

As well, avoid those "PMPO" or "peak" ratings. They only state what an amp can deliver in transient response, not durations.

Heres what you want, assuiming you are running a 4-ohm sub, look for something with these specs(or better).
100 watts RMS(not peak) into 4ohms(if it is 2ohms, cut the power rating by two-unless your sub is 2 ohms), for 20Hz-200Hz(just make sure they don't say just one frequency like 1kHz, it means it might not have the same muscle in the frequencies that matter), with less than 1% THD.

Probably confusing I know, but an amp with above specs is most likely better than most of the "Super-duper-mega-bass 800 watt" amps out there.