Okay. I'm not new to any part of the automotive industry but to this day I do not understand the reason of using ohms in speakers and such. I know ohms is the measure of resistance. and i know the ohms law so on and so forth. but if ohms is the measure or resistance wouldnt you want less ohms like daul 2 ohms not daul 4 ohms? what does ohms signify in speakers? 2 ohms per voicecoild or what? how would you configure the ohms of the subs to match that of the amp?
You have to match the ohms of the subs to the amp. An amp is only rated to handle a certain amount of ohms because everytime you cut the amount of ohms in half the current that goes through the amp is doubled... until the point that it fries. A sub having that amount of resistance is the only thing that keeps the amp from frying itself, or switching into protect mode depending on the amp.
So to kinda answer your question. Lets say you have 2 chanel amp that will handle a 2ohm stereo load (which is what most do). That means you could get two dual 4 ohm subs and hook the voice coils on each sub in parralel to each channel on the amp, which would give it 2 ohms per chanel and it would be operating at the highest output it can safely. So the wiring would look like this picture:
Or lets say you wanted to hook two dual 4 ohm subs up to a mono amp that can handle 1 ohm (a lot of mono class d amps can handle 1 ohm loads safely anymore). It would look like this:
And again the reason you have to wire them like this is so the amp can handle it. I hope this answered your questions, if you have any more just ask.
Oh and sorry about posting again, I reread your original post and maybe you were referring to why do the voice coils on subs have to have resistance at all. Well it is the resistance that makes the cones move. The voice coil is an electromagnet inside the sub and as electricity goes through it the electromagnet turns either positive or negative and pushes it away from the outside magnet on the sub... kinda.
Check this out for a better explaination. Pretty much if they didn't create any resistance (ohms) then the electromagnet wouldn't work and the speaker wouldn't move.
thanks skyler LOTS of useful info. Still a little confussed. So it doesnt really matter what the ohms of the sub is as long as the the ohms of the sub is larger than the amp? why when you double the resistance using two subs does the ohm level drop on the amp?
Resistances in series R1 + R2 + R3 + R4........+Rn
Resistances in parallel R1 * R2 * R3 * R4......*Rn
. . . . . . . . . . . . R1 + R2 + R3 + R4......+Rn
RJ Miller wrote:thanks skyler LOTS of useful info. Still a little confussed. So it doesnt really matter what the ohms of the sub is as long as the the ohms of the sub is larger than the amp? why when you double the resistance using two subs does the ohm level drop on the amp?
Kind of. The final resistance of the sub (the load presented to the amp) matters because it has to be in range of the amp's capabilities. Let's simplify it even more. Say you have a mono sub amp (one channel) that is capable of loads down to two ohms and at 4 ohms it's rated at 400 watts. A 4 ohm single coil sub will get 400 watts. A dual coil 4 ohm sub wired in parallel will get 800 watts by bringing the amp to a 2 ohm load, thus doubling the output of the amp. But wire the same sub in series will present an 8 ohm load, thus cutting the power of the amp by half (200 watts). Now, if you have a dual 2 ohm sub, wiring the coils parallel will present a 1 ohm load which the amp is unable to handle, but wiring the coils on the same sub in series will present a 4 ohm load.
Now, remember, not all amps are capable of doubling the power when resistance is cut, but as a rule of thumb, every time the resistance is cut in half, the power is doubled. Let's again say it's an amp that's rated 400 watts at 4ohms: 4ohm-400 watts; 2ohm-800 watts; 1ohm-1600 watts; .5ohm-3200 watts. Same goes when doubling the resistance. Every time you double the resistance, the power gets cut in half (8ohms will get 200 watts, 16 ohms will get 100 watts, and so on).
"Wenn ich gehen lasse von, was ich ich bin, werden Sie, was ich bedeutet werde, um zu sein."
Lower overall resistance is also harder on the amp - which is the disadvantage to the extra power you get. Most amps have no problem with 2 ohms though.
Very true. But some amps are more stable at lower resistance. I ran Nexxus amps in my S-10 when I was competing in dB Drag and those babies didn't perform consistently unless you ran them at 2 ohms or less. Down to .5 ohms they'd run like a champ, just had to worry about power supply and heat. They took a lot of current to run right and they got hot pretty easily.
"Wenn ich gehen lasse von, was ich ich bin, werden Sie, was ich bedeutet werde, um zu sein."
not to mention that when you aplly a very small resistance...amperes go up. when amperes go up so does distortion exponentially. MEANING- all things being equall, 8 ohms will have half the distortion of 4. resistance is necessary to put less of a load on an amp. too little resistance, and youll burn it out. thats my explanation for why there is resistance at all. if youll note also...car speaks are 4ohm, and homespeaks are 8 ohm.......why, you say? well its like this, when you have lots of amperage, you need little voltage, and the opposite is true. in a house you have lots of voltage, but not much in the line of current. so if you double the voltage, you can cut the amperage in half. so now, in a house you have like 20 amps, as opposed to like 200. and in direct relation, from 120volts instead of 12. see a multiples of 10 thing there? thats what i mean by exponentially. ohms law explains that numerical relationship.
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