# What sounds better, 2 or 4 Ohm?



## laserred97gt (Feb 26, 2010)

Hey guys,

I am getting one Sundown SA-8. I will be running it from an Infinity REF1600A amp. The sub is going in a 1.1cu/ft ported box tuned to 34Hz.

The Infinity puts out 400W RMS @ 4 ohm and 600W RMS @ 2 ohm. The SA8 is rated (probably conservatively) @ 400W RMS.

From a SQ standpoint, would it be better to get a Dual 2 ohm subwoofer and run the voice coils in series @ 4 ohm - 400W, or get a Dual 4 ohm and run them parallel at 2 ohm total - 600W? (more headroom?)

Thanks for any advice you can give.


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## Oliver (Jun 25, 2007)

If the alternator and battery = electrical system is up to a massive dumping of power { mono block for sub }, go with it !


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## basshead (Sep 12, 2008)

IMO

if the amp is not doing double the 4ohms wattage at 2 ohms it's probably bc it doesn't have a very strong DC to DC PS, so in your case i guess it would be better to run at 4ohms.

Personnaly I would find a Sundown 1000d for cheap to power this puppy


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## laserred97gt (Feb 26, 2010)

a$$hole said:


> If the alternator and battery = electrical system is up to a massive dumping of power { mono block for sub }, go with it !


Does that mean 2Ohm is better for SQ? 

The main question I have is... 

*"From a SQ standpoint, would it be better to get a Dual 2 ohm subwoofer and run the voice coils in series @ 4 ohm - 400W, or get a Dual 4 ohm and run them parallel at 2 ohm total - 600W? (more headroom?)"*


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## laserred97gt (Feb 26, 2010)

basshead said:


> IMO
> 
> if the amp is not doing double the 4ohms wattage at 2 ohms it's probably bc it doesn't have a very strong DC to DC PS, so in your case i guess it would be better to run at 4ohms.
> 
> Personnaly I would find a Sundown 1000d for cheap to power this puppy


 I think a 1000d might be a bit much, but then I'd have room for a MAJOR upgrade down the road! 

Jacob (@ Sundown) recommended a SAX-125.2 as a perfect completment to this 8" sub. It wasn't in the budget at the time, but may be down the road. :surprised:

I really wish my budget supported 2 more 8's and the 1000d.

Thank you for the thoughts. Is there any other thoughts, or did basshead hit the nail on the head?


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## Candisa (Sep 15, 2007)

basshead said:


> if the amp is not doing double the 4ohms wattage at 2 ohms it's probably bc it doesn't have a very strong DC to DC PS


Indeed, and the result --> less headroom on the power supply --> less dynamics at low impedance.

50% more power will only give you less than 2dB more output (if sensitivity in dB/W/m is the same), and only if the sub can handle the extra power.

A 4 ohm load will result in a more stable running power supply --> better dynamics.


After searching for specs of that SA-8, I came to the conclusion it is VERY inefficient and I can't find linear excursion of the thing. Personally, I wouldn't even use it if I got it for free after seeing those specs, or it would be for making a video about efficiency and compare it with a CSS Trio8 with only half the power on it (which doesn't have such a fantastic efficiency either, but it's a LOT better than the efficiency of that Sundown)...


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## rommelrommel (Apr 11, 2007)

Are we seriously talking about the essque of 2 vs 4 ohm with a frickin SA8?


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## laserred97gt (Feb 26, 2010)

Candisa said:


> Indeed, and the result --> less headroom on the power supply --> less dynamics at low impedance.
> 
> 50% more power will only give you less than 2dB more output (if sensitivity in dB/W/m is the same), and only if the sub can handle the extra power.
> 
> ...


Thanks for the excellent reply. I will run 4ohm

I am looking for a lot of bass in a small package, to fit my space constraints. the xMax is 19mm one direction from what I've read. I agree that the sub isn't the best SQ sub out there, but there is no harm in making it sound the best it can, right?


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## jel847 (Nov 8, 2007)

rommelrommel said:


> Are we seriously talking about the essque of 2 vs 4 ohm with a frickin SA8?


hahahaha...
yes we are!


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## benny (Apr 7, 2008)

moar ohms is moar essque


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## SQfreak (Feb 13, 2007)

ok this thread = FTL


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## Candisa (Sep 15, 2007)

laserred97gt said:


> Thanks for the excellent reply. I will run 4ohm
> 
> I am looking for a lot of bass in a small package, to fit my space constraints. the xMax is 19mm one direction from what I've read. I agree that the sub isn't the best SQ sub out there, but there is no harm in making it sound the best it can, right?


With that efficiency, you'll never reach 19mm of excursion without serious over-power.

If you want just 1 8" subwoofer, you have 2 options:
- get the maximum SPL level out of it, but only be able to play down to 35ish Hz if you don't want a HUGE box size and/or port length
- get it as low as possible by putting it in a sealed enclosure, but have less SPL output.


Even with limited space, I think you're better of with a high excursion 10" subwoofer. A single 8" driver will never be able to get low and loud enough at the same time to use as a subwoofer in a car.

I think something like a CSS SDX10 in a .7-1.0 cu.ft. sealed enclosure would be a much better option.


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## Oliver (Jun 25, 2007)

This will do what you are wanting 

JL Audio 8W7 - 8" Subwoofers - Sonic Electronix



> # 8" Single 3 Ohm W7 Subwoofer
> # Power Handling:
> 
> * Peak: 1000 watts
> ...


A Sundown or amp that dishes out 800 watts @ 4 Ohms will work


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## 89grand (Nov 23, 2006)

I run at 32 ohms for max essque. Granted, I'm only getting about 4 watts per channel, but it's worth it.


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## el_chupo_ (May 27, 2007)

89grand said:


> I run at 32 ohms for max essque. Granted, I'm only getting about 4 watts per channel, but it's worth it.


Zuki watts?


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## deesz (Feb 1, 2010)

long story short not really it doesnt matter at 2 or 4 ohms. when you look at the bigger picture it could but I don't think you me or half the other people would ever hear it. for us its just a way to match up power of the amp to power of the sub.
oh i have used that amp before it doesnt really like 2 ohms.


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## Candisa (Sep 15, 2007)

4W at 32 ohms is indeed VERY low power, even if you use amps that double power perfectly 
[email protected]
[email protected]
[email protected]
[email protected]

I think it's a very long time ago I've seen an install that has such a low power amplifier...


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## 14642 (May 19, 2008)

That amp is fine into 2 ohms and that's what you should use. All of this 4 ohms is more esq is ridiculous. Vented box and 2-ohms is the right thing.


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## MaskMan (Jan 27, 2010)

Candisa said:


> With that efficiency, you'll never reach 19mm of excursion without serious over-power.
> 
> If you want just 1 8" subwoofer, you have 2 options:
> - get the maximum SPL level out of it, but only be able to play down to 35ish Hz if you don't want a HUGE box size and/or port length
> ...


This I am agreeing with now. 
I had a plan to run a single 8" iD8v3D2 in my Tacoma and feel it is not enough. 

I have it in a .36cf sealed box with 350w and volume is rather lacking, of course it is also not a very efficient woofer with lots of excursion and low power handling. I figure with the small box it can take maybe 180-200w RMS.

I hit the limits fast (bottoms out, which could in part be poor damping factor on the Amp, not sure yet) and it is not loud enough or go low enough for me. 

I might build another box for a second one (it does sound very good) or just go with a 10" JL Stealth box. Not what I want but would work overall. Maybe change the driver at a later date to a better one. 

Technically with the efficiency on the iD at 85db and RMS at 150w the thing will only play up to 107db or so. But with the steep low-end roll-off it doesn't seem that loud and almost no low-end extension without massive bass boosting. I guess this is about 1.3 times as loud as 1w. I also agree, I do not think I am getting 17mm excursion at least not controlled...

On the other-hand, I built a car with 4 8" subs and 600w (with 2db headroom on that amp) that was very loud and low with tuning, but it used larger sealed boxes and more efficient subs.

Oh and Candisa: 
I run a SoundStream D60II that is only 30wpc 4ohm. I also have an Eclipse tweeter amp that is 10wpc 4ohm @.009THD (not in use now, but I think I will be using it in my other build). Not sure about running 32ohm tho


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## Candisa (Sep 15, 2007)

Mr. Wehmeyer: Look, I know you're a respected man in the audio scene, including this forum and I'm sure you know more about audio than 99.5% of the people on forums, but you really have to explain to me how pushing the power supply, buffer and output-mosfets to their limits by running in high-current can be a good thing for sound quality, especially if all that power is wasted on a <80dB/W/m efficient 8" subwoofer? 
I really don't get why running in 4 or even 8 ohms on a more efficient sub isn't a lot better, but maybe that's just me, since older (green) Infinity speakers sound a lot better to me than white ones too?


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## audiogodz1 (Jan 5, 2010)

I can hear the difference in smoothness at 8 ohm, but between 2 and 4 it only seems a tad more raw. between 4 and 1 I can tell a decent difference.


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## tanakasan (Sep 8, 2007)

el_chupo_ said:


> Zuki watts?


Must be!

Robert


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## Andy Slater (Oct 21, 2009)

IMO 4 ohm sounds better. Distortion from amp goes up with lower impedance. Some of the new 2ohm stuff still sounds good. The Image Dynamics 2ohm stuff is nice, Theres some other stuff out there that is nice also, I prefer go 4 ohm and get a bigger amp. ( I'm just sayin)


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## Candisa (Sep 15, 2007)

There's only 1 reason why there are so many 2ohm/DVC drivers available in the car audio scene: you can push more Wattzzzzz out of an amp with them. That's important for the local 18 year old that drives an old Civic with 5 Civic's worth of bodykit on it and a Sony explode (I know it's not written like that!) "sound system", but that same 18 year old does not know what Sensitivity or Efficiency means and doesn't know that rating this in "dB" is meaningless and doesn't know what the difference is between "dB/W/m" and "dB/2.83V/m". That same 18 year old probably is known to "know a lot about tuning and audio" and only thinks that ported boxes are not only louder but also always better than sealed enclosures "because the pressure can come out of it".

Amps are not power amplifiers but voltage amplifiers and they only give more power at lower impedance because current goes up. The only reason why amps are built to handle that extra current is because people could build arrays that are more efficient by wiring the drivers in parallel to eachother and to handle impedance dips that some speaker systems might have.

Most amps that are "2ohms stable" do not double their power output at 2 ohms compared to with a 4ohms load. This means when output current goes up, stable output voltage goes down at lower impedance loads. That kind of amps are NOT 2ohms stable and should be rated as "won't die of a 2ohms load". BIG difference!

Pushing an amp so hard that it's maximum stable output voltage goes down can NEVER be good for it, and that's exactly why amps go dead if you lower the impedance load too much, why they run hotter and less efficient at lower impedance loads, and why THD goes up at lower impedance loads.

I do NOT say people should always buy the highest-impedance version of a driver available and I'm definately not saying that people shouldn't wire voice-coils/drivers in parallel, but I DO say pushing amps to their limits is not the way to obtain good sound quality and must be avoided.

I said it before and I say it again: it has it's reasons why we have 230V at home here in Europe (where you can't go to court to obtain a money-claim from the electic company with "My dog licked an electric socket in the wall and dropped dead")...

greetings,
Isabelle


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## kyheng (Jan 31, 2007)

^Some(more) power turns into heat when running lower impedence. But nowadays, people like to see big number rather than small numbers.


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## lil goat (Oct 16, 2009)

This thread is funny, assuming the amp and driver are matched correctly the impedance of the speaker has ZERO effect on the sound. In most situations it is better to run 4 ohms if you can just so the amp runs cooler, just because an amp supposedly will run at 2 ohms, doesn't mean you should run it at 2 ohms, many amps are marginal at best at 2 ohms, but the marketing department won't let them put "this amp sucks ass at 2 ohms, but it won't blow up" in the spec sheet. Take the time to spend your money wisely, if you can afford to do it right, my suggestion is to wait until you can, you will be much happier in the long run.


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## 14642 (May 19, 2008)

The point is that the amplifier is designed to make some particular voltage and has a maximum current delivery capability. We build amps for 2 ohms and use the real 4-ohm rating. As Candisa has clearly stated, amplifiers don't "current limit" they power limit. When the current demands exceed the capability, the voltage falls to reduce the current delivery. That causes distortion, but it's no more distortion than a clipped signal into a 4-ohm speaker. 

If you don't get enough bass from your system, then there are several things you can do. 

1. If you use a sealed box, rebuild it as a vented box. That'll give you more bass at the expense of space. 

2. Reduce the impedance to get more power from the amp. This won't add many decibels because amps don't make double the power into half the impedance as a matter of practice. 

3. Add more speakers.

4. Use a more efficient driver.

If you hear distortion that sounds like bottoming, it coud, in fact, be bottoming in the speaker or it couldbe odd-order distortion caused by a clipping amp. It has nothing to do with circuit damping or damping factor because those are meaningless. It means you need more power or more woofer. A single 8" in a sealed box isn't a giant bass machine.


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## Candisa (Sep 15, 2007)

Now that's an explination I can live with, but I would put the solutions to get more output in another order 

First step: raise the efficiency of the system by using (a) more efficient driver(s)
Second step: Raise the efficiency further by using a ported box, but know that it requires a huge box or costly passive radiators to reach a low tuning frequency
Third step: increase maximum SPL by adding more speakers
Fourth step: increase power, but I would prefer using a more powerfull amplifier instead of running at lower impedance to push more out of the same amp.

In my own car, I use an oldskool Crunch 600 amplifier with 2 4ohm subs series-bridged. This way, I have enough power (because it's a very powerful amplifier) and maintain a 4ohms per channel load.

There are only 2 reasons to get the power you want by using low-impedance drivers:
- Because you have a low budget (600W @ 8ohms is more expensive than 600W @ 2ohms) --> Get a used amp instead of a new one, much better solution for a budget problem
- Because space is limited ([email protected] will be more compact than [email protected]) --> First make the system as efficient as possible, a 2ohms system won't get any louder than a 2dB/W/m more efficient 4ohm system on the same amp and requires less current from the cars power system!

greetings,
Isabelle


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## cubdenno (Nov 10, 2007)

The efficiency rating of a speaker does not necessarily hold true in figuring overall system efficiency.. Even if you narrow it down to just the sub. I have seen several 82 db rated subs get louder on same power as higher efficiency rated subs. My guess is usually because the higher rated subs efficiency is questionable or the efficiency rating given does not come into play at the frequencies we are asking subwoofers to play. My guess is head to head the SA-8 is going to play as loud or louder in the 30-60 hertz range as any majority of other 8's out there on the same power. 

Though I agree mostly, I will buy a 1 ohm stable amp and wire my subs to the lowest load I can safely (not killing anything electrical) wire to. Odds are the amp I am using can handle the load, The distortion is not going to be THAT high unless I am clipping amp, The class of amp I am using is generally more efficient so less of a strain on my electrical system, I don't have room for a 4ohm 2000 watt amp, and 2000 watts at 4 ohms is pulling the same power from my electrical system as 2000 watts at 1 ohm. I truly do not have space for a 2000 [email protected] ohm amp.


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## Candisa (Sep 15, 2007)

To compare efficiency, you actually have to compare the FR plots or even better: simulate the drivers in WinISD in the right box, with the power you're giving them.

Space is indeed a good reason to get the power you need by wiring drivers down to the lowest impedance load possible.


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## Oliver (Jun 25, 2007)

Andy Wehmeyer said:


> It means you need more power or more woofer. A single 8" in a sealed box isn't a giant bass machine.


The point is that scratching your balls with a feather is pointless


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## cubdenno (Nov 10, 2007)

a$$hole said:


> The point is that scratching your balls with a feather is pointless


HA!!


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## 14642 (May 19, 2008)

a$$hole said:


> The point is that scratching your balls with a feather is pointless


What about scratching them with a rabbit?


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## sqshoestring (Jun 19, 2007)

Andy Wehmeyer said:


> What about scratching them with a rabbit?


Rabbits eat carrots right?


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