Thread: I need to some basic information about amps

Originally Posted by Bust_A_Cap

Allright.....i'm new to this forum and pretty new to car audio systems in general. I am interested in putting in a computer in my van but I am also interested in just uprgrading the speakers first. The only problem is that i want to put new Xlpod 6 X 9 in but they require a minimum of 75-100 watts to run. The cd player i have right now outputs 50 watts for 4 channels <pretty normal from what i understand>. This leads to the fact that if i want to put new speakers in, the i will need to get a...or some amps to power the speakers.

So i started searching around on the internet for amps and what i was looking for was something like an amp that had like 150-200 watts on 4 channels <150-200 on each channel>. So I started searching the internet for something between a 600-800 watt amp. I kept finding that the amps would say 800 watt 4 channel amp, but then it would say something like 100 watts per channel, or 2 150 watt bridged channels, or something of that sort. This brings me to my question.....when it says how many watts are per channel, is that a minimum or is that all that it can output? What happened to the other 200-400 watts?

If my question isn't exactly clear then tell me so and i will try and clear it up a bit.
THANK YOU!!!

I wouldn't recommend the Xplod speakers.. They DON'T need 75-100W.. This is their peak wattage!!!! You can run them with your HU!!!

The 800W you read for the amp may be the peak power and not the RMS!!!

Generally stay away fromsony speakers!!

You can drive every speaker you want with your HU!!!
The question is, is it worth to have GOOD speakers driven by the HU??
NOPE!!!

Don't expect to have loud and CLEAR music with sony speakers!!!

It depends on what you want and your budget!!!

welcome to car audio! the most fun hobby I have picked up yet! By now, I assume youve discovered there are differences between RMS ratings, and peak ratings. RMS is a good standard to run by. fewer "junk" companies rate their amplifiers using RMS ratings, because lower numbers dont sell as well as bigger numbers. So, finding an amplifier thats rated for 100 watts per channel peak is often an indicator of a poorer brand than one that rates at say, 50 watts RMS per channel. This rule doesnt always apply, and some companies (earthquake is the only one I can think of) use peak ratings yet are quite reputable, indeed. The standard conversion is to double RMS to get peak levels. This also is a general rule. a great example of this would be those BOSS amplifiers that say 3000 watts on teh amp, then the fine print says 500 rms. 300 watts indeed! We like to say that its 3000 watts ISL. Its a joke, saying itll do 3000 watts If Struck by Lightning

That being said, the next issue, with power, is that there is no standard in the car audio market for measuring power. Thus, a company like clarion can rate their amplifiers using a 1000 Hz tone, where its very easy to make power, and rate their amplifiers at 50 watts into each of four channels. Compare that amplifier to a Zapco or an Arc audio 50 watt 4 channel amplifier, and you may be left wondering why the arc amps are so much louder! Well, if the company uses a more vigorus standard to rate power, then the amp might be much stronger than its even rated for! This practice is called "underrating" an amp. many many companies do this, like earthquake, Arc, TRU, old high end hifonics, etc.

Your radio is rated for 50 watts peak into four channels. read the fine print, it will be no more than 23 RMS. My pioneer is rated for 45 watts into four channels, the fine print states 19 RMS per channel. know your power production!

You say you found aan 800 watt amp, that says only 100 RMS into each of four channels. again, its the selling point. the amp is capable of producing 100 rms into a 4 ohm load in each of four channels. read the fine print, the amp is 2 ohm stable. thus, at 2 ohms, assuming the amplifier is unregulated, will put out 200 watts RMS into a 2 ohm load on each of four channels. add up all teh channels, thats 800 watts! many times, amplifier companies will name the amp "800.4" or "800/4", so you know its a four channel amp, capable of producing a maximum of 800 watts, distributed across four channels. if they follow this selling guide line, and the amplifier is 1 ohm stable while operating in stereo mode (not bridged) then youd expect the power ratings to say 50x4 at 4 ohms, 100x4 at 2 ohms, 200x4 at 1 ohm, 200x2 at 4 ohms, and 400x2 at 2 ohms (x2 means bridged, x4 means stereo) see how it doubles like that?

Quality of amplifier most definitely can have an effect on sound! just how much, I will get into after talking a bit about speakers. Depending on your situation, thelong and the short of it is you can have any experience from not being able to tell the difference between that BOSS 3000 watt amp and an Audison HR100, all teh way to being able to easily distingush an audison from a TRU amp. details later.

Now that we know there are different standards for measuring amplifiers, we can see why people here dont reccommend feeding 75 RMS into those sony speakers! again, feed it 1000 Hz tone, itll take 75 rms all day. now try feeding it a 100 Hz bass note at 75 rms, and see how fast you can cook it! likewise, youll find companies that underrate their speakers, knowing their customers will overdrive them. JL is a perfect example of this. take a look at any of the V1 subwoofers, they are rated to handle about half of what they can take, and the box reccommendations are half teh voluem the speaker needs to sound ideal. its all because they know kids are gonna feed them more power than they are rated for, then cry JL sucks when they blow. underrate them, and the kids wont feed them as much power to the destruction point. neat trick, eh?

so why do people not reccommend sony, after all this? heres a neat trick you can do at home. go grab the bassiest CD you own, and go out to a department store with sony 6x9's on a demo board. play them and turn up the bass like you assume all the kids do in their cars, and watch the speakers actual motion through their wide open grills. specifically, watch the red cone. see the waves in the cone? We call that "cone flex." you should also notice at this time, the speakers will sound like junk on the bass hits. most 6x9's will have this issue, with some rare exceptions (of course, not one car audio rule is absolute). the solution is to use a highpass filter for the speakers. the most basic ones are called "bass blockers", and are jsut capacitors that filter out bass frequencies. But if you use them, you lose all the bass that 6x9's are "supposed" to be able to play due to their large cone size.

My reccommendation is to go with a solid pair of 6.5's, once that you can see have no clone flex, that you know can play as low or lower than the 6x9's at a higher sound quality. you can cut a piece of wood in teh shape of a 6x9 and cut a 6.5 inch hole in that for your 6.5's; its not an issue of round versus oval, its an issue of cone flex. I cant think of ONe person who actually desires cone flex in their car!

Ever hear people complain that when they upgraded their car speakers, they lost all their bass? they wonder why their stock speakers had so much more bass than their aftermarkets? cone flex!

Someone above suggested a radio or amplifier didnt do much in their car, but when they changed the speakers, they noticed a HUGE difference. this is the case in almost every car out there. The fact is, your speaekrs define your sound. period. There is no such thing as an amplifier that will make a pair of crappy sounding speakers sound good. if you have crappy sound, and adding an amp made them good, it was because you had a crappy amp making a pair of good speakers sound crappy, not the other way around. speakers are going to be ALL of your sound. dont skimp here!

As to teh argument that a radio will never have a quality output for a set of good speakers, my girlfriend runs a pair of koda components up front, a pair of tangband 6.5's in teh back, all run off deck power of a sony radio. If anybody would like to know, PM me after August 7th, I'll let you know how she did at Sound Quality competition. My prediction is she doesnt take last place. Or you can talk to my buddy who opted to keep the 6 disc in dash changer in his WRX (wise decision) but added aftermarket amplifiers, speakers, subwoofer, etc. it sounds *****in!

Back to the speakers/radio/amplifier for YOUR van issue. (if you are still reading at this point) You want something reasonably loud, but not for 3 grand. totally understandable! the fact is, running a set of efficient speakers off the radio will give you all the volume you could want underneath the "extremely loud" category. the key words are efficient! Someone else here mentioned eficiency. You also may have noticed a speaker rating called "efficiency" (measured in dB) reading the fine print on a speaker. Bull****, bull****, bull****, its all lies. its as meaninless as the 75 watt rating on those sony 6x9's, its as phony as the 3000 watt power rating on that boss amp! true efficiency from a powerhandling perspective is achieved through real world testing, not through ratings of power. perfect example: the adire shiva (its a 12 inch subwoofer) has an efficiency rating of 87 dB. the audiobahn Q 12" subwoofer has anefficiency rating of 96 dB. (I should mention that a driver is a driver, whether its 6.5 inches, 6x9, 1", or 15") the rating is "with one watt of power from a distance of one meter." thus, if you feed each subwoofer the same power, say, 100 rms, the audiobahn should be 9 dB (roughly twice as loud sounding) louder than the shiva, right? except the AB gets its *** handed to it by the shiva. why? efficiency! the shiva is just better at taking power and turning that into audible sound. We hear mroe of it, since that power is going into teh sound, and not into making the cone move! thus we have efficiency!

You can find many awesomely loud speakers out there. adire kodas come to mind, as do earthquake focus, polk (whatever that $400 set is) Digital designs w6's, tangbands, there are too many to list, these I just pulled out the top of my head. They all have one thing in common. they probably wont be as loud as those sony 6x9's if you play them off deck power. why? they need that 75 rms to get SUPER loud, to break into the realm of "extremely loud"! feed them both 75 rms, and the EQ focus will wipe the floor with the sonies. off deck power? well, its gets a bit more questionable. from a volume standpoint, of course. So what speakers are efficient? which can you run off deck power and expect to get almost as loud as they can get? look at your infinity reference series speakers, your rockford fosgate fanatic P series, your JL VR (borderline) speakers. these will all give you a quality sound without *requiring* the use of an amplifier to get the most out of the speaker. the sonies, pioneers, alpines, JL tr series, earthquake cheapies, clarion speakers, etc, will have a difficult time keeping up in the sound quality department to these others. But they can get every bit as loud. you'll just have a bit more mud in the sound, thats all. and even then, only at high volumes.

So which is the best speaker? well, thats impossible to say the infinities have no midbass. the rockfords have tons of midbass, but the tweeters scream. so do infinity kappas. so do EQ's. JL VR are smooth, but they are borderline best with an amp, and expensive. What is the conclusion? speakers dont sound "better" or "worse", they sound different. the best thing to do is to go out to a demo board and lsiten for yourself. Focus not on the sound, but on teh differences in sound between speakers. everyone will tell you they sound different in teh board than in yrou car. well, if you switch back between the rockfords adn teh infinities, and hear teh rockfords have more midbass, you can expect mroe midbass in yrou car. stuff like that.

So now youve picked a set of speakers for your van. will teh amp make a difference in quality of sound? Well, if you went with a sony or a pioneer, you probbaly wont get a difference in sound with an amp. itll get a heck of alot louder, thats for sure! but a quality difference? thats alot harder to prove! When you start to get into yoru adire kodas, your focal polyglass, polykev, your cdt eurosport speakers, you can suddenly hear teh nuances between smplifiers a bit better.

Go encode some MP3's. get a pair of songs and encode them both at 64 bitrate. dont the cymbals all sound the same? now listen to the cd quality recordings (you ahve to do this on hi-fi speakers, or headphones). can you hear the cymbal differences now? a higher quality recording lets you hear the nuances of the music more. And so it is with audio equipment. Ever wonder why people drop $30,000 on a set of tower speaekrs for the home? they like to be able to hear the difference between a good recording, and bad and like that, a set of speaekrs like JL VR will better be able to hear a quality difference between a clarion or earthquake amp and a TRU versus those sony speakers. which, I hazard a prediction, would sound the same (with identical tuning, of course.)

Well, if you are still reading at this point, im sure you are bored as hell. I know you asked for teh time, and I basically told you how to build a watch, but for what its worth, there you go.

I jsut realized I forgot to go into resistances, and why lower ohm ratings are not more efficient than higher ones. do you guys actually care? I realize its a windy post..... (and I dont guarantee its 100% perfection, everyone feel free to take it apart and amend it....)

10,000 character limit my butt! thats weak!