Ohms For Subs...?
Ohms For Subs...? Just curious...what is the difference between 2 & 4 Ohm and how do I know which is right for me? Does one or the other just make more power than the other?
Im looking at the Kicker Line of Subs. The Solobaric models in 10"
I listen to all kinds of music if that helps.
Im looking at the Kicker Line of Subs. The Solobaric models in 10"
I listen to all kinds of music if that helps.
Joined: Nov 2003
Posts: 11,328
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
2-ohm and 4-ohm refer to the impedance of the speaker. Impedance is the opposition to alternating current in much the same way as resistance is opposition to direct current flow.
Asking which is better is somewhat like asking if metric wrenches are better than SAE wrenches. Neither is better - you just use the one that fits properly. However, there are situations where you can use the "wrong" one and have it work fine - just like you can use a 13mm wrench when you don't have a 1/2" wrench available.
Using the Monsoon system as an example, the doors have 2-ohm woofers but most common aftermarket speakers are 4-ohm. You can use 4-ohm speakers in the doors although the higher impedance will tend to reduce the volume output. The reason that it doesn't is because of another measure of speakers - efficiency. Efficiency is a measure of how well a speaker converts the electrical energy from the stereo into sound waves. Almost all quality aftermarket 4-ohm speakers are far more efficient than the stock 2-ohm speakers. That means that even though their increased impedance reduces volume, their better efficiency compensates so that the net difference is very small.
Going back to the wrench analogy...I'd rather use a high quality 13mm (0.51") wrench on a 1/2" bolt than a really cheap 1/2" wrench that might be 0.52" or larger. Even though it wasn't the "correct" wrench, it would still work better.
Asking which is better is somewhat like asking if metric wrenches are better than SAE wrenches. Neither is better - you just use the one that fits properly. However, there are situations where you can use the "wrong" one and have it work fine - just like you can use a 13mm wrench when you don't have a 1/2" wrench available.
Using the Monsoon system as an example, the doors have 2-ohm woofers but most common aftermarket speakers are 4-ohm. You can use 4-ohm speakers in the doors although the higher impedance will tend to reduce the volume output. The reason that it doesn't is because of another measure of speakers - efficiency. Efficiency is a measure of how well a speaker converts the electrical energy from the stereo into sound waves. Almost all quality aftermarket 4-ohm speakers are far more efficient than the stock 2-ohm speakers. That means that even though their increased impedance reduces volume, their better efficiency compensates so that the net difference is very small.
Going back to the wrench analogy...I'd rather use a high quality 13mm (0.51") wrench on a 1/2" bolt than a really cheap 1/2" wrench that might be 0.52" or larger. Even though it wasn't the "correct" wrench, it would still work better.
Last edited by WhiteBird00; May 18, 2007 at 08:38 AM.
Staging Lane
Joined: Sep 2005
Posts: 54
Likes: 0
From: Lake Charles
It kindof depends on whether you get dual voice coil subs, # of subs and the ohm stability of your amp. 2 ohm stable amp get two 4 ohm subs wire in parallel, dual voice coil subs get two 2 ohm Subs, the voice coil on the subs in parallel, and the subs in series w/ one another. What kind of amp and power are you willing to pay for?
In door speakers I heard that the better more efficient 4 ohm speakers give you better sound quality but require more power. Whereas the 2 ohm speakers sound loud with less power but they tend to not be very clear and precise.
With subs the clarity and accuracy is really much less important whethr you use 2 ohm or 4 ohms. Its all about how you wire them and what type of amp you get and what type of voice coils you use etc.
Most try to get a 1 ohm stable amp thats single channel and then set up their subs to be wired for 1 ohm. Otherwise the other big bunch of people get a 2 channel amp and bridge it . then you wire of your subs for a 2 ohm load, then you will get good results.
With subs the clarity and accuracy is really much less important whethr you use 2 ohm or 4 ohms. Its all about how you wire them and what type of amp you get and what type of voice coils you use etc.
Most try to get a 1 ohm stable amp thats single channel and then set up their subs to be wired for 1 ohm. Otherwise the other big bunch of people get a 2 channel amp and bridge it . then you wire of your subs for a 2 ohm load, then you will get good results.
Joined: Nov 2003
Posts: 11,328
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
The impedance of a speaker has nothing to do with its sound quality. That's like saying a 100 watt bulb is better quality than a 60 watt bulb. Yes, it's brighter but that has nothing to do with quality. Picking an amp (or speakers) because you want a particular impedance is just plain dumb. 
You want to match the speaker impedance to the output of the amp. Every amp will be rated for watts of power into a specified impedance. Not all amps are stable (can safely run) at lower impedances such as 1-ohm or even less. So you have to get speakers that match the capabilities of your amp - connecting a 1-ohm sub to a 2-ohm stable amp is a good way to fry the amp.
Now, assuming that the amp is stable down to the level you want, using a lower impedance speaker will mean more power output while having no effect on sound quality. For example, a two channel amp rated at 160 watts RMS per channel at 4-ohms could run about 240 watts RMS per channel at 2-ohms and maybe 480 watts RMS when bridged into one channel at 4-ohms. This particular amp is not 2-ohm stable when the channels are bridged so your choice would be to run two 2-ohm speakers at 240 watts each or one 4-ohm speaker at 480 watts. Same total output, different configurations. In other words, pick the amp first and then worry about what speakers will work with it.
You want to match the speaker impedance to the output of the amp. Every amp will be rated for watts of power into a specified impedance. Not all amps are stable (can safely run) at lower impedances such as 1-ohm or even less. So you have to get speakers that match the capabilities of your amp - connecting a 1-ohm sub to a 2-ohm stable amp is a good way to fry the amp.
Now, assuming that the amp is stable down to the level you want, using a lower impedance speaker will mean more power output while having no effect on sound quality. For example, a two channel amp rated at 160 watts RMS per channel at 4-ohms could run about 240 watts RMS per channel at 2-ohms and maybe 480 watts RMS when bridged into one channel at 4-ohms. This particular amp is not 2-ohm stable when the channels are bridged so your choice would be to run two 2-ohm speakers at 240 watts each or one 4-ohm speaker at 480 watts. Same total output, different configurations. In other words, pick the amp first and then worry about what speakers will work with it.
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thanks whitebird00, i was banging my head against the wall with the other responses.
all the ohms are is the resistance in the voice coil. you want to maximize the power by choosing the subwoofer impedence correctly.
now on a side note, any amplifier will run warmer with a lower impedence, and so efficiency will go down, but as long as you stay within the factory specs, you should be fine.
all the ohms are is the resistance in the voice coil. you want to maximize the power by choosing the subwoofer impedence correctly.
now on a side note, any amplifier will run warmer with a lower impedence, and so efficiency will go down, but as long as you stay within the factory specs, you should be fine.
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Originally Posted by WhiteBird00
Now, assuming that the amp is stable down to the level you want, using a lower impedance speaker will mean more power output while having no effect on sound quality. For example, a two channel amp rated at 160 watts RMS per channel at 4-ohms could run about 240 watts RMS per channel at 2-ohms and maybe 480 watts RMS when bridged into one channel at 4-ohms. This particular amp is not 2-ohm stable when the channels are bridged so your choice would be to run two 2-ohm speakers at 240 watts each or one 4-ohm speaker at 480 watts. Same total output, different configurations. In other words, pick the amp first and then worry about what speakers will work with it.
I do believe you want the highest ohm load possible though. It is much easier on the amplifiers. Decreasing a speakers impedance also decreases sensitivity. So even though it will draw more power from the amp, it doesn't mean it will be louder.
With everything else being equal, a 4 ohm driver being power with 100 watts will be just as loud as a 2 ohm driver being powered with 200 watts.
the real question is what amp do you plan on using? when we know that we can determin where at what load your amp best performs. then we can tell you which subs to you use whether 2 or 4ohm or dvc or not.
Joined: Nov 2003
Posts: 11,328
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
Originally Posted by 95bat
With everything else being equal, a 4 ohm driver being power with 100 watts will be just as loud as a 2 ohm driver being powered with 200 watts.
However, that last statement is simply outlandish. Efficiency is not a linear value - a speaker is no where near twice as efficient at twice the impedance. Doubling the power to a speaker will noticeably increase the volume (it won't double it - that takes ten times the power) regardless of the impedance or the efficiency of the speaker (within reasonable limits of course). Any speaker running 200 watts of power will be about one third louder than the equivalent speaker at 100 watts even if the impedance is different.
LOL I used to think the same way 
Here is some reading for you:
http://www.diymobileaudio.com/forum/showthread.php?t=31
It is kind of confusing at first, but after you read about it, it makes sense.
Here is some reading for you:
http://www.diymobileaudio.com/forum/showthread.php?t=31
It is kind of confusing at first, but after you read about it, it makes sense.
Joined: Nov 2003
Posts: 11,328
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
Originally Posted by 95bat
LOL I used to think the same way
Here is some reading for you:
http://www.diymobileaudio.com/forum/showthread.php?t=31
It is kind of confusing at first, but after you read about it, it makes sense.
Here is some reading for you:
http://www.diymobileaudio.com/forum/showthread.php?t=31
It is kind of confusing at first, but after you read about it, it makes sense.
But, in any case, you are right and I shouldn't have jumped on your statement like I did. I think we agree that speaker impedance shouldn't be the first or only deciding factor for equipment purchases. Find the equipment you want...then match the impedance.
Originally Posted by WhiteBird00
I think we agree that speaker impedance shouldn't be the first or only deciding factor for equipment purchases. Find the equipment you want...then match the impedance.
I do think this is the reason why most component sets are 4 ohm though
Grants them a high efficiency and nowadays they have awesome power handling as well! Makes for very loud component systems hehe.