Well class take your seats it's time for another lesson. Today were going to learn about car audio and the terms associated with it, and what they mean.
Let's begin!
Ohm's
Okay ohms or Ohm's law is the rule of resistance that something has. Most of you probably think about things like rubber and all having high resistance and that is correct. But in car audio we use ohms for what a speaker's resistance is at. For example if you have a sub that has a 4 ohm single voice coil. Than that sub can be wired up to an amp with the resistance of 4 ohms.
The next part of Ohms is power. If you look at any amp's specs you will see that is has something like 100 watts RMS x 4 at 4 ohms (150 watts RMS x 4 at 2 ohms) 300 watts RMS x 2 bridged output at 4 ohms (4-ohm stable in bridged mode) so lets look at the first one. This one states that is can run 100 watts per channel "or speaker" as long as each speakers has a resistance or Ohm's of 4. The second one states that as long as all the speakers are at 2 ohms the amp can put out 150 per channel. The last one shows that it will put out to 2 channels 300 watts a channel if there ohms are 4 ohms. "you will also notice that is says 4 ohm stable at bridged mode." This states that the amp was built for the load of 4 ohms and is able to be bridged.
The thing with ohm's is that the higher the ohms the more resistance. So when you go with a lower ohms rating it can have much more power to run that speaker. You may be asking well can I wire different ohm rated speakers to two different sets output on an amp? You can ONLY do this if the amp is setup for it. If you want to get relay technical about Ohms law just google it and click on any of the first few links that come up. Or just simply ask.
RMS
Now you may have notice in the previous section when watts were being explained it said RMS. Something like 100 X4 at 4 ohms RMS. This is very important when choosing an amp. RMS stands for root mean square. In normal terms this means what an amp can continue to produce for long periods of time none stop. You may bee seeing things like 1200 watts MAX. In a few simple words this is a gimmick the amps will never produce this power and no matter how hard you try there just not going to make it. You always look at RMS when shopping for an amp. You will even see it on head units saying 50 X 4 max it is rely putting out around 12-15 watts RMS.
Amp Settings and Gains
So great you got your new amp and are wondering what in the world are all these knobs and switches on it for? Well here is your answer. Gain or volume. Some even say it differently than that but the deal with this is, think of it as a adjustment to insure your not clipping the signal. When you are all done installing your system is it time to put a test disk in of a normal song or a test tone of 80HRZ go to your amp and turn the gain all the way down than go back to the head unit and turn the volume 1/4 to full volume. Now you go back to your amp and slowly start turning up your gain until you hear distortion than turn it back just a hair. This will insure that your speakers are not going to distort or clip.
Now those Low pass and High pass knobs and all. Well a normal setup consists of your fronts being components. "speakers with separate tweeters" So the crossover will take care of the filtering of all that so your front should stay on Full. If you are going with rear speakers I would turn on the High pass filter and dial it to around 80 or maybe a bit higher. What these filter do are basically insure that the speaker will not get frequency's that it can not reproduce. The Low pass filter is fro when running a sub woofer your cut off should be around 60 for your sub.
Crossovers
So you know that little box that comes with your component speakers and some coaxial speakers. There things are called crossovers. Basically what they do it take the unfiltered signal that your amp sends it and sends the frequency's to the tweeter and the proper frequency's to the woofer. Some people like to turn there high pass on there amp to around 100HRZ so that way it takes more strain off the crossovers. It is a personal thing I prefer to let the crossovers to there thing.
Sub Wiring
This and this alone is the trickiest to master of everything in car audio. There are so many was to wire subs that it is very hard to explain, but I am going to try my best. There are 4 kinds of subs which included there Ohm's and all. There is a SVC "single voice coil" 4 ohm and a 8 ohm formats. Than there is a DVC "dual voice coil" 4 ohm and 2 ohm formats. The SVC are pretty easy. You can hook up a 4 ohm coil as a 4 ohm or if you have 2 you can wire them as 4 or 2 ohms. If you have a SVC 8 ohm sub than you can hook it up as 8 ohms. If you have 2 of them you can hook them up as a 4 ohm load. You can not wire different ohm rated subs or speakers together this will damage the sub and or the amp.
Which brings me to DVC subs. Honestly there are so many ways to wire them that I would hope that you IM me or consult this guide to help you wire them properly.
Subwoofer Wiring Diagrams
As always if you have any questions or comments let me know.
Next lesson will be on rely's, power wire, fuse ratings, and how much current until you have to upgrade your alt, and all. ENJOY!