Mathematically, this becomes: Current in amperes equals voltage in volts divided by impedance in ohms. So increasing the voltage increased the current. If the voltage decreases back to 10 volts, the current will decrease back to 1. Now, if our amplifier with 10 volts output is connected to a 4 ohm speaker, the lower impedance will allow more current to flow.
Finally, if we can measure or in some other way determine the amount of current being drawn from the amplifier, we can calculate the value of the load impedance using Ohm's Law. We will use this shortly to figure out what happens when we connect several speakers to the output of an amplifier. The formula for this is: Impedance in ohms equals Voltage in volts divided by Current in amperes. Also connect the black terminal of the amp to the black or '-' terminal of the speaker.
If you feed a pure tone through the amp so that it delivers 10 volts to the speaker, the current flow through the speaker as we saw above should be 1.
The first thing to understand is that the voltage output from the amplifier does not change. In reality, it might drop just a hair, but for this discussion let's assume a perfect amplifier. So it's still 10 volts AC. And since each speaker is connected directly to the amp's output terminals, each speaker will receive 10 volts from the amplifier.
As we saw earlier, if 10 volts is applied to an 8 ohm speaker, it will draw a current of 1. And if each speaker needs 1. If you add a third speaker, it will also draw another 1. If you keep adding speakers, at some point the speakers will demand more current than the amplifier can deliver, and it gives up its smoke and dies. Too many loads is an overload. See importance 1, above.
Now, we are ready for impedance. As we said earlier, if you know the voltage and can figure the total current, you can calculate the total impedance of all the speakers together by dividing the voltage by the total current. A single speaker is simple: 10 volts divided by 1.
Remember that two 8 ohm speakers would draw a total of 2. So 10 volts divided by 2. What about 3 speakers that draw 3. Four speakers that draw 5 amperes from a 10 volt source have a total impedance of 10 volts divided by 5 amperes which equals 2 ohms.
As more speakers are added, each one draws additional current from the 10 volt source, so there must be less total restriction of current.
Well, what if the speakers have different impedances? Like an 8 ohm cabinet and a 4 ohm cabinet? The same method can be used. To make it simpler, remember that impedance was a physical property that doesn't depend on the voltage. The speaker has the same impedance whether the source is 10 volts or 1 volt.
So let's use 1 volt to make it simpler. Both together draw 0. Notice that the total is less than the lowest value speaker. While the calculations may seem complicated, examination of the results above reveals some patterns that make things much easier.
First, if all speakers or cabinets have the same impedance ratings, the total impedance can be found by using the impedance value of one speaker and dividing that by the total number of speakers.
If you go back to our example of 8 ohm speakers, we found that a single speaker had a total impedance of 8 ohms duh Your security and privacy are ensured. Our advisors cannot see anything that is on your computer. They only have the ability to "serve" a page from our site and put items in your cart.
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Cancel my request. It's your turn. See bio. We will be calling you. We're sorry. We have encountered a problem. Sorry, the call-back feature is currently unavailable. How wiring affects your sub's output. Meet Buck Pomerantz Close. More about Buck Started at Crutchfield in Completed our thorough in-house Advisor training, learning about the ins and outs of our various products Stays up-to-date by attending vendor training sessions for new products Earned MECP Mobile Electronics Certified Professional certification Designed and organized Crutchfield's subwoofer wiring diagrams Authored dozens of Crutchfield articles and hundreds of product presentations, primarily focused on car audio amplifiers and pro audio gear Answers the many customer questions posted in the comments on his articles Semi-retired soundman with decades of experience making other people sound good From to , also worked as a sidelines video camera grip for University of Virginia football and basketball games.
Comments Read comments. Jake, If you're asking will a watts RMS rated amplifier work with two watts RMS rated subs, the answer is no - the amp will probably blow them to smithereens.
But without knowing precisely what amp and subs you're referring to, we can't help you with accurate advice. If you want a question answered about a system, you must identify the gear by brand names and model numbers so we can get the right information to you. Anthony, It sounds like you need to talk to an Advisor about what you have, want, and what's possible for your sound system.
To start with, sending watts to a speaker rated for will kill it. So there's no reason to describe how to wire them together. Also, tweeters don't off-set power, they play different frequency ranges at the same power level as their matching woofers. Plus, without knowing precisely what amp and speakers you're referring to, we can't help you with advice. Aaron, Yes, two SVC 4-ohm subs can get wired together to form a 2-ohm load.
However, you should be aware that that amplifier is capable of putting out watts RMS at 2-ohms, which is enough to blow those two watts RMS, watts RMS together, rated subs. We recommend getting a less powerful amp for those subs. Give us a call, so an Advisor can help you pick out the perfect gear for your system.
Darwin, The output of most amplifiers will react differently to different impedance loads. Theoretically, an amplifier will put out four times the power through a 2-ohm load as it would through an 8-ohm load. In the practical real amplifier world, the results will vary. Those subs are rated for watts RMS each, so that amp will work well with them wired like this.
Raymon, The impedance of a component sub inside a powered subwoofer assembly is irrelevant to any other system consideration and won't affect any other component.
Aaron, That amp is powerful enough to fry your rear speakers and subwoofer. But you should be alright as long as you set the amp gain low enough to never allow distortion to play. Josh, That'll depend on how your present subs are wired. Two DVC 4-ohm subs can be wired as a 1-ohm, a 4-ohm, or an 8-ohm load. If yours are set up as a 1-ohm load, two DVC 1-ohm subs can also be wired as a 1-ohm, so the sound quality and power handling will remain the same.
Shop our selection. The easiest way to shop car audio online Find what Fits your vehicle Remove. Checking fit Related products. Kicker 44DCWC In stock. Pioneer GM-A I guess my concern is weather or not the person who added the extra jack might not have known what they were doing and somehow the amp isn't 4ohms any longer. Can you see what I'm saying?
I guess the only way to tell would be to open it up and see how it's wired. I don't have a clue what to look for. Is it worth even worrying about? The amp works fine and sounds great. Maybe I should just let it go. Now I can play with peace of mind.
Some times I wish I took a different path in the 70s. Output transformers don't have an "impedance rating" per se. The transformer itself has no idea whether it's a "4 Ohm", "8 Ohm", "16 Ohm", whatever. What it DOES have is an "impedance ratio".
Impedance ratio determines what load impedance will be reflected to the primary side with a given load impedance connected to the secondary side. It is calculated by first finding the voltage ratio which is equal to the turns ratio , then squaring that figure i.
In order to find the voltage ratio, you would have to feed a known AC voltage into the primary, then measure the unloaded voltage out at the secondary. You would then divide the primary voltage by the measured secondary voltage. You then multiply that figure by itself to get the impedance ratio. Once you know the impedance ratio, you can multiply the impedance ratio by the known impedance of a load to calculate the impedance that will be reflected to the primary side.
An output transformer is nothing more than a power transformer that operates at audio frequencies. You could even use wall voltage as your "primary test voltage" on it, then measure the secondary output to get your voltage ratio. Wilder Amplification , Mar 13, Last edited: Mar 14, I will also add that the amp must be off, power valves removed and no speaker connected to the speaker jack prior to connecting wall voltage to the primary of an output transformer.
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