# Benefit of running a sub at 4 ohms vs. 2?



## Lance_S

I see subs that are 4 ohm rated and some that are 2 ohm rated. Just wondering if you are going to run a single sub, what is the benefit of running a sub in 2 ohm vs. 4 ohm.

My understanding is that when you drop to 2 ohm you double the power (or close to it, depending on the amp). But isn't it wise to take into consideration the power handling capacity of the sub? Is more always better?

My thought is that I have a sub amp that at 4 ohms will output 500 watts continuous. If I were to purchase a morel ultimo SC which handles 600 continuously wouldn't I be better off running it at 4 ohms?

If I bought the 2 ohms version, the amp will output around 800 watts. Then I will also double my distortion and over power the sub. Now I know they put some fluff into the sub continuous handling numbers to protect the sub, but the goal is for SQ, not spl. Besides, I can't image that with 500 Watts of really clean A/B power going to it that it won't thump pretty hard.

Just wanted to get your thoughts. 

Thanks,

Lance


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## minbari

this is going to start ****storm, but here goes.

4ohms is WAY better than 2 or 1ohm for a few reasons. easiest one is tolerances. if you have a D2 sub and wire it for 1 ohm you have to consider the other losses in the system. connectors, wire, tolerance in the sub, etc. 

so for the sake of argument, lets say that you have an additional 1/4 ohm of resistance from all those sources. so now you have 1 1/4 ohms on the amplifier. let say that your amplifier is 1000watts @ 1ohm. At 1 1/4 ohm you will have 800 watts. that is a 20% loss.

so lets take the same scenario and instead make it 4 ohms. so 1000watt amplifier @ 4ohms and a D2 sub wired to 4ohm with an extra 1/4 ohms in connects, etc. with 4 1/4 ohms you will have 941 watts.  that is only a 6% loss.

add to the fact that most amplifiers run much more efficient at higher ohm loads since they have higher voltage and lower current, its a win win.


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## kyheng

There's no benefit actually.... Since running 4ohm the number are small compare to running at 2ohm....
But there's lots of benefits of running 1 or 2ohm, you can fry an egg or boil some water on your amp's heatsink... Not to mention disco lights effect on your headlight.....


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## MarkZ

minbari said:


> this is going to start ****storm, but here goes.
> 
> 4ohms is WAY better than 2 or 1ohm for a few reasons. easiest one is tolerances. if you have a D2 sub and wire it for 1 ohm you have to consider the other losses in the system. connectors, wire, tolerance in the sub, etc.
> 
> so for the sake of argument, lets say that you have an additional 1/4 ohm of resistance from all those sources. so now you have 1 1/4 ohms on the amplifier. let say that your amplifier is 1000watts @ 1ohm. At 1 1/4 ohm you will have 800 watts. that is a 20% loss.
> 
> so lets take the same scenario and instead make it 4 ohms. so 1000watt amplifier @ 4ohms and a D2 sub wired to 4ohm with an extra 1/4 ohms in connects, etc. with 4 1/4 ohms you will have 941 watts. that is only a 6% loss.
> 
> add to the fact that most amplifiers run much more efficient at higher ohm loads since they have higher voltage and lower current, its a win win.


Efficiency is usually better, yes. But as we've learned from some of the other threads around here lately, lots of people place a premium on eeking out every last watt out of their amplifiers. In that case, the lower impedance is better for most amps.


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## minbari

MarkZ said:


> Efficiency is usually better, yes. But as we've learned from some of the other threads around here lately, lots of people place a premium on eeking out every last watt out of their amplifiers. In that case, the lower impedance is better for most amps.


I dont mean to use the same amplifier. I mean 1 amplifier is 1000watts @ 1ohm and the other is 1000watts @ 4ohms. the 4ohm systems will have advantages over the 1ohm system.

if you ran a 1ohm stable amplifier @ 4ohms, then yes, you will suffer from only having 1/4 the power.


BTW, WTF is up with the new quote view? looks like crap


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## bmiller1

minbari said:


> BTW, WTF is up with the new quote view? looks like crap


Agreed


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## MarkZ

VBA strikes again.


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## spl152db

minbari said:


> I dont mean to use the same amplifier. I mean 1 amplifier is 1000watts @ 1ohm and the other is 1000watts @ 4ohms. the 4ohm systems will have advantages over the 1ohm system.
> 
> if you ran a 1ohm stable amplifier @ 4ohms, then yes, you will suffer from only having 1/4 the power.
> 
> 
> BTW, WTF is up with the new quote view? looks like crap


I thought it was just me. I say everyone who pays, cancel now until its fixed. or deal with it. 

oh and as far as the losses, yes thats possible, but not likely. since you have to consider the resistance will not be measured the way you presented it. 1ohm and .25 equals .2 ohms. 4ohms and .25 equals .235. I wouldn't want either of those values. 

you're talking straight up loss. loss will be a percentage not a resistance. like 2% loss and with power the same, loss the same.


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## minbari

spl152db said:


> I thought it was just me. I say everyone who pays, cancel now until its fixed. or deal with it.
> 
> oh and as far as the losses, yes thats possible, but not likely. since you have to consider the resistance will not be measured the way you presented it. 1ohm and .25 equals .2 ohms. 4ohms and .25 equals .235. I wouldn't want either of those values.


not talking parallel resistance. a 2ohm sub with a series 1/4 ohm in resistive losses would be 2 1/4 ohms.


> you're talking straight up loss. loss will be a percentage not a resistance. like 2% loss and with power the same, loss the same.


ahh, but it isnt. if you had 2% across the board I would agree. but with the same 1/4 ohm loss in connectors and wire, then your 1ohm sub vs 4ohm sub becomes the variable. 1 1/4 ohm with 1/4ohm in series resistance vs 4 1/4 ohm with only 1/4 ohm in series resistance.. 1/4 ohm for a 1ohm sub is a MUCH higher percent than it is for the 4ohm sub.


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## Lance_S

lol, thanks guys. Don't want to start a Sstorm! I remember reading NPDANG's article on running 8 ohm speakers on a 4 ohm car amp. Thought process was similar in effeciency. I don't like to abuse my equipment and never thought that I needed the extra power. The sub I have currently is pretty efficient. If i stepped up to one that was less efficient I guess I will cross that bridge when I come to it. But currently, I don't run any of my amps under a 4 ohm load although they are fully capable of it. Thanks!


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## Catman

I'd be running 8 or 16 ohm if possible for the increase in damping factor and SQ. I have ran 0.5 ohm with no problems with lights dimming or overheating ....SQ suffered though.

>^..^<


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## The A Train

For those who are dropping the load resistance to squeeze every last watt out of their amp will not have an amp very long.


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## minbari

The A Train said:


> For those who are dropping the load resistance to squeeze every last watt out of their amp will not have an amp very long.


Depends on the amplifier. I ran 4 hifonics amps in the 90s to their potential for years. They were well built.

Sent from my Motorola Electrify using Tapatalk


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## Catman

The A Train said:


> For those who are dropping the load resistance to squeeze every last watt out of their amp will not have an amp very long.


The amp I mentioned above was stable to 0.25 ohm. It was an old school Orion HCCA.

>^..^<


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## ZAKOH

Make take is that you should not worry too much about subwoofer impedance. Yes, if I could afford to buy a mono block amplifier that can provide the sufficient wattage at 4ohm for the subwoofer, I'd do that. It will run more efficiently. But if I already had a 2ohm sub or an amplifier that doesn't provide much power at 4ohm, I'd run at 2ohm. Right now I am powering a 4ohm sub with two bridged channels, so I end up running the amplifier channels in 2ohm effectively.


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## minbari

Catman said:


> The amp I mentioned above was stable to 0.25 ohm. It was an old school Orion HCCA.
> 
> >^..^ <


those were only 1/2 ohm stable


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## skdooley

The main difference is efficiency of the amp (how much current is drawn from the electrical to create its rated power) and dampening (control) over the sub(s) being played. Higher the ohm load, the better the efficiency of the amp and the greater control you have over the subs. The difference between the two really isn't that great, you would have to go from 4 ohm to 1 ohm for a more noticeable difference, IMO. The greater factor here as far as sound quality over your subs is going to be up to the enclosure they're in and the subs being ran. Install has the greatest effect on output. Efficiency is efficiency though. A lower ohm load is normally "cheaper" to run a given amount of power, but it will simply take more power to make that power.


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## lopezel

I've never run anything lower than 4ohms even if my amps/speakers have the capacity. I don't see the need to put an extra strain on my electrical system, cause any more distortion, etc.


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## fish

I had an Alpine PDX1.1000 which puts out 1k @ 2-4 ohms. It was a night & day difference switching from 2 to 4 ohms. That amp never even felt like it was on when @ 4 ohms. Two ohms is the lowest impedance I'll go, though not preferred.


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## pat_smith1969

assuming an amp that is stable at 2 ohms and 4 ohms...it is slightly better to run it at 4 ohms. That allows the amp to run cooler and maybe live longer (depending on the amps and stuff though). So if you are able run it at 4 ohms..

by far the bigger concern here is to put the right power on the speaker. Being able to run an amp at either 4 or 2 ohms allows you to output two different wattages and this allows you to chose different subs (or if you have the sub it allows you to select different amps). 

if able, I go 4 ohms, but if I must go 2ohms I don't worry about it too much. And the change in SQ really doesn't come into play too much with a sub.. at these ohms.


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