# running subs at 1ohm, who does it?



## Frank Drebin (May 30, 2011)

I've always shied away from loading down amps to <2 ohms, but it sure opens up a lot of options with respect to amp selection.

For those of you who run down to 1 ohm on your sub amp, how do you like it? Does sound quality suffer? Harder on the charging system? I'm guessing the amp gets quite hot?

Would I be better off paying for the power @ 4 ohms or can I push an amp to 1 ohm with ease.

Thanks


----------



## minbari (Mar 3, 2011)

if the amplifier is designed to run at 1 ohm, then it makes no difference. SQ will within specs. some are better built than others.

watts are watts. the amount of current drawn by an amplifier will be based on how many watts it produces and how efficient it is. output impedance has nothing to do with it.

again, how hot it gets has nothing to do with output impedance. if it is well designed, it will operate just fine. I have seen amplifiers that got hotter at 4 ohms than another brand did at 2 ohms.

am I sounding like a broken record yet? power @ 4 ohm or 1 ohms will be determined by the design. if it is designed for 4 ohms, then run it at 4 ohms. if it is designed for 1 ohm, then run it at 1 ohm. people have this idea that a lower impedance automatically means more power. couldn't be farther from the truth.


----------



## ChrisB (Jul 3, 2008)

I'm running a True Bass Ultra 8 at one ohm off a 500 watt Lunar L1500 in my wife's 2011 Hyundai Genesis Coupe. It was the perfect complement to her existing "premium" sound system that lacked the low end she was used to.



Frank Drebin said:


> For those of you who run down to 1 ohm on your sub amp, how do you like it?


My wife loves how the add on sub complements her factory setup and makes it sound "complete" as she puts it.



Frank Drebin said:


> Does sound quality suffer?


Not in the least bit. Remember, the sub bass area of the sound spectrum is where the human ear is least sensitive to changes in frequency.



Frank Drebin said:


> Harder on the charging system?


Nope, and I'm running a class ab amplifier at 1 ohm! Less efficient, perhaps, but her stock electrical handles it just fine.



Frank Drebin said:


> I'm guessing the amp gets quite hot?


Nope, it's fan cooled and if you go with a properly designed class d amplifier, heat will be even less of an issue.



Frank Drebin said:


> Would I be better off paying for the power @ 4 ohms or can I push an amp to 1 ohm with ease.


I can't answer that one for you. If you are one of those who believes that you can hear things such as damping factor and the difference between 1% distortion and .1% distortion on a subwoofer, maybe. In the real world scenario of actually driving your vehicle, you'd be hard pressed to tell the difference on subwoofers between a properly designed quality class d amplifier at 1 ohm mono and another comparable amplifier at 4 ohms.


----------



## Frank Drebin (May 30, 2011)

Great news!

So, suggestions on properly designed amps? Looking at 1000-1.5k RMS @ 1 ohm.


----------



## cubdenno (Nov 10, 2007)

What the other guys said!!!

I also run a sub with a DCR of 1 ohm on my SAZ1500D. No issues. Class D amp. Does not get hot. Barely warm with most music. Efficiency at playing noise wide open was a measured 75% +- 3% fluctuations in my car with stock electrical. 

People worry to much regarding how a sub will sound. Get the enclosure right. Run the amp that will get you the power you want in the space you are willing to give up. Most 4ohm X watts are generally bigger and costlier than a 1 ohm X watter.


----------



## cubdenno (Nov 10, 2007)

Frank Drebin said:


> Great news!
> 
> So, suggestions on properly designed amps? Looking at 1000-1.5k RMS @ 1 ohm.


Sundown SAZ-1500d. Been in my car for 4 years. Bullet proof. Lotsa power. Classy looks. Adequate heat sink.


----------



## minbari (Mar 3, 2011)

cubdenno said:


> What the other guys said!!!
> 
> I also run a sub with a DCR of 1 ohm on my SAZ1500D. No issues. Class D amp. Does not get hot. Barely warm with most music. Efficiency at playing noise wide open was a measured 75% +- 3% fluctuations in my car with stock electrical.
> 
> People worry to much regarding how a sub will sound. Get the enclosure right. Run the amp that will get you the power you want in the space you are willing to give up. *Most 4ohm X watts are generally bigger and costlier than a 1 ohm X watter.*


that has more to do with the class than the ohm stability. Class A/B are much bigger in size than thier Class D counterparts.


----------



## cubdenno (Nov 10, 2007)

minbari said:


> that has more to do with the class than the ohm stability. Class A/B are much bigger in size than thier Class D counterparts.


Absolutely. But it can be a determining factor in buying an amp. Often gets overlooked when buying and then you get it home and try to make it fit and uh oh! God knows I have made that mistake!:blush:


----------



## ChrisB (Jul 3, 2008)

cubdenno said:


> Get the enclosure right.


A BIG X2 here. The process of adding my wife's subwoofer was the first time I used predictive modeling combined with measuring a vehicle for cabin gain with a RTA. I built a test box out of particle board shelving because I was unsure of how my calculations would work out. As a result, the cheap test box ended up being the final enclosure.:laugh:


----------



## Frank Drebin (May 30, 2011)

ChrisB said:


> A BIG X2 here. The process of adding my wife's subwoofer was the first time I used predictive modeling combined with measuring a vehicle for cabin gain with a RTA. I built a test box out of particle board shelving because I was unsure of how my calculations would work out. As a result, the cheap test box ended up being the final enclosure.:laugh:


Well if you are limited on space and location, all you can do is try your best with what you have right? 

Truthfully I don't understand how you can build a sealed box right or wrong. If its sealed, and the proper volume, its built correctly?


----------



## ChrisB (Jul 3, 2008)

Frank Drebin said:


> Well if you are limited on space and location, all you can do is try your best with what you have right?
> 
> Truthfully I don't understand how you can build a sealed box right or wrong. If its sealed, and the proper volume, its built correctly?


Her enclosure is ported, .62 cubic feet tuned to 32 Hz. When modeling, it produced more low frequency extension with cabin gain compared to most 10s that fit in the same space. Sadly, most of the 10s that I modeled had a predicted F3 in the low to mid 50 Hz range. Furthermore, I only paid $65 for her True Bass Ultra 8.


----------



## wooferdog (Mar 31, 2011)

i have been using a jbl bp 1200.1 at 1 ohm for over 6 years and no issues at all.it's a class d stable to 1 ohm. puts out 1200+ rms and doesnt break a sweat and easy on the charging system.


----------



## envisionelec (Dec 14, 2005)

1 ohm "nominal" operation is a bad idea if you want a reliable amplifier. Let's dissect this by amp class:

*Class A/B:*

Requires more paralleled output transistors. This puts a strain on the driver transistors due to the higher current flow in the output devices. Many "low impedance stable" amplifiers are not designed to cope with this effectively (many can't drive 2 ohm nominal loads correctly) and deliver current in a non-linear fashion - even below full output. Negative feedback cannot correct for beta droop which is the SQ killer for low impedance operation. Note that this only applies to BJT output devices. MosFET devices don't have these issues, for the most part, but still need multiple paralleled devices. Very few amps these days are using MosFET outputs in such plurality. Actually, I can't think of any. 

*Class D:*

Output [carrier filter] inductor current is very high. Saturation is imminent which makes the inductor cores very hot. I've rarely seen a mainstream car amplifier with a sufficiently large output inductor. Some even run hot at idle!!

For all topologies, increased current equates to increased ripple voltage that is seen by the rail filter capacitors. This ripple is exacerbated by stressed magnetic components operating near their saturation point. Ripple produces heating in the capacitors and is the primary cause of cap failure.

Many amplifiers are designed with poor overcurrent protection. Simple  current limiting just looks at the voltage across an emitter resistor and only at frequencies below about 100Hz. More advanced current limiting involves slope compensation which takes impedance, source material and existing allocations into account. Your typical "car amp" isn't going to have this much thought put into it - so it's best to stay away from the 'hairy edge' of the design _even if the marketing department says it's OK_.


----------



## minbari (Mar 3, 2011)

envisionelec said:


> 1 ohm "nominal" operation is a bad idea if you want a reliable amplifier. Let's dissect this by amp class:


if it is designed to run at 1 ohm, then it is fine. are you going to suggest that an amplifier that is 2ohm stable should never be run lower than 4 ohms? if a well designed amplifier is "1 ohm stable" that means it will run 1 ohm all day long. the reality of it is that amplifier is more then likely 1/2 ohm capable, but not recommended. so 1 ohm is just fine. as long as you stay in the range that the manufacturer specifies you are good. 

this idea that you shouldnt run something to its potential in electronics is silly. it isnt a car engine that will wear parts out. it is a power supply plain and simple. (just has the ability to modulate the output into AC)


----------



## chad (Jun 30, 2005)

envisionelec said:


> 1 ohm "nominal" operation is a bad idea if you want a reliable amplifier. Let's dissect this by amp class:
> 
> *Class A/B:*
> 
> ...



I agree with everything said here but people still think I'm insane.


----------



## ChrisB (Jul 3, 2008)

chad said:


> I agree with everything said here but people still think I'm insane.


I could go back and rehash what a certain repair tech/vendor said about high voltage versus high current, but I'll make it quick. To paraphrase, he said that high impedance/high voltage amplifiers were the best for the car. Then in his next sentence, he pointed out some of the refurbished amplifiers that he had for sale. This is also the same guy who told a USACi competitor that he had a "modified" amplifier that would do 1,500 watts RMS @ 8 ohms all day long on a 60 amp slow-blow fuse!:laugh:

Looking back at some of the mistakes I made with regards to car audio, I am still asking myself: "WTF were you thinking to believe that steaming pile of horseshit?"


----------



## envisionelec (Dec 14, 2005)

minbari said:


> if it is designed to run at 1 ohm, then it is fine. are you going to suggest that an amplifier that is 2ohm stable should never be run lower than 4 ohms? if a well designed amplifier is "1 ohm stable" that means it will run 1 ohm all day long. the reality of it is that amplifier is more then likely 1/2 ohm capable, but not recommended. so 1 ohm is just fine. as long as you stay in the range that the manufacturer specifies you are good.
> 
> this idea that you shouldnt run something to its potential in electronics is silly. it isnt a car engine that will wear parts out. it is a power supply plain and simple. (just has the ability to modulate the output into AC)


In order for a given amplifier to operate into a 1 ohm load, you pay more for the same amount of power than if you were operating at 4 ohms. You pay because there is more overhead with an amplifier designed to operate at 1 ohm loads. 

I know you think you're smart from the way you write your posts, but take a walk in my shoes. I design power supplies and amplifiers for a (part time) living and will be doing it full time in the near future. I happen to know why it's a really stupid idea to build an amplifier that drives 1 ohm nominal loads. There is so much waste in various losses that it makes no sense. There used to be a reason to have a 1 ohm stable amplifier and that was to compete in autosound classes by "cheating" the system. There are now _no good reasons_ for having a low impedance drive amp.

_Your statement that "parts won't wear out" is telling above all._ Sure they wear out. Capacitors lose their capacity to hold a charge. Inductors can be saturated or heated and permanently lose their properties to transfer magnetic fields. Bipolar transistors suffer from secondary breakdown caused by molecular changes to the N and P channels producing "hot spots" and ultimately failure of the device. How do you think amplifiers fail, anyway?


----------



## minbari (Mar 3, 2011)

I agree that there is no good reason to run 1ohm loads. if you have 1/4 ohm of connection losses you lose alot more power at 1ohm, than at 4 ohms. try and talk the automotive audio manufacturers in to that

I will stand by statement for parts though. I have stuff that is 15 years old and still works. caps dry out and have to replaced, sure defects happen and stuff breaks. cars break down too, doesnt matter how well designed. but in electronics if things are not designed on the edge, they dont wear out.


----------



## envisionelec (Dec 14, 2005)

minbari said:


> I agree that there is no good reason to run 1ohm loads. if you have 1/4 ohm of connection losses you lose alot more power at 1ohm, than at 4 ohms. try and talk the automotive audio manufacturers in to that
> 
> I will stand by statement for parts though. I have stuff that is 15 years old and still works. caps dry out and have to replaced, sure defects happen and stuff breaks. cars break down too, doesnt matter how well designed. but in electronics if things are not designed on the edge, they dont wear out.


Many (most?) car amps built in the past 10-12 years are designed on the edge. They are designed to fail or at least perform poorly even if meeting the "power" spec. 

*[going off topic...]* I wish *wish wish* I could have some time to evaluate some of these "rebranded" amps that Sundown or whomever doesn't design their own amplifiers or have an engineering department (not to pick on Sundown, but they came to mind) to evaluate their true performance on the standard battery of real audio tests for IMD (specifically TIMD), PSRR, crosstalk and so forth. You don't find these measurements ANYWHERE these days, but by gosh, it sure does screw up the sound and it's far more audible than you'd ever imagine! It's really no wonder car amps get a bad rap - some are truly awful.

Power output is important to people that want to get loud. Quality can be measured and heard. Can anyone tell me how to pick the feedback node in an amplifier? How is a high PSRR achieved? What effect does a low PSRR have on an amplifier's sonic performance? How are specific types of distortion mitigated? *[back to topic]*

"Still works" must be followed by "how well?". Does it perform as it was designed from the beginning? Chances are it does not if it was ever used or stored in a non-climate controlled environment. I have amps that "still work" but fall into the "needs replacement parts" category to meet spec. Note that meeting spec doesn't mean meeting what's written in the manual, but meeting the design intent.

Your original point was lost in your response. I'm not here to argue, but to state the case backed up with facts.


----------



## tonesmith (Sep 8, 2011)

I guess thats why Zed is so against these low loads. If your end goal is a robust,reliable good sounding amp then by definition 1ohm stability is not an option.

I agree with the "it works" comment. Just because you could doesn't mean....well you know.


----------



## minbari (Mar 3, 2011)

tonesmith said:


> I guess thats why Zed is so against these low loads. If your end goal is a robust,reliable good sounding amp then by definition 1ohm stability is not an option.
> 
> I agree with the "it works" comment. Just because you could doesn't mean....well you know.


yup, exactly right.

take this as an example:
1)

(2) 4ohm DVCs wired parallel to 1ohm. with all the speaker connections, combining the wires in a connector and then connecting to the amplifier. lets say you lose 1/2 ohm in connection losses.
you connect to a 1000watt amplifier, 1 ohm stable. at 1 1/2 ohms (with losses) your amplifier will have a max output of 666Watts. that is a loss of 33% power 

2)

(2) 4ohm DVCs wired series-parallel to 4ohms. same losses of 1/2 ohm.
a 1000watt amplifier @ 4ohm. at 4 1/2 ohms (with losses) you will have a max output of 888watts. now it is only a 12% loss. the only thing you changed was the final output impedance of the amplifier. the size of the woofers and the output of the amplifiers were the same.


----------



## kyheng (Jan 31, 2007)

Well, nothing wrong on running 1ohm at any 1 time, since music are dynamic.... Or someone wants to say he is a robot and will only listen to test tones all the time, then running 1ohm load maybe a problem....


----------



## cubdenno (Nov 10, 2007)

envisionelec said:


> Many (most?) car amps built in the past 10-12 years are designed on the edge. They are designed to fail or at least perform poorly even if meeting the "power" spec.
> 
> *[going off topic...]* I wish *wish wish* I could have some time to evaluate some of these "rebranded" amps that Sundown or whomever doesn't design their own amplifiers or have an engineering department (not to pick on Sundown, but they came to mind) to evaluate their true performance on the standard battery of real audio tests for IMD (specifically TIMD), PSRR, crosstalk and so forth. You don't find these measurements ANYWHERE these days, but by gosh, it sure does screw up the sound and it's far more audible than you'd ever imagine! It's really no wonder car amps get a bad rap - some are truly awful.
> 
> ...


I have a SAZ1000d (Sundown 1000 watt at 1 ohm sitting on a shelf.) a JBL GTO14001 (1200 watts at 4 ohm 1500 at 2 ohms) and if you could do it quick, a Sundown SAZ1500D ([email protected]) ohm i would be willing to loan you to test. I have seen the SAZ1500 run at .35 DCR or something stupid at a SPL meet. with rise it was around 1.2 ohms. Was not my amp. but the one I am referring to is still in use, used a a daily driver sub amp. Almost had my hands on a RD1750. Same amp board (zenon) as the SAZ1500. Just rated as a 1750 watt amp at 1.

A buddies Orion HCCA225 wired to (4) 2 ohm subs for a DCR of .5 ohms from 1993(?) is still running. He bought it from a store in Danville Illinois. Same subs same amp. strong electrical system. When I visit him in my traveling I always look at that thing in amazement. A strong Class A/B amp!! His second one is driving his mids and tweeters. The sub amp gets a bit warm......

Maybe it does cause a sonic difference. I just know I can't hear it. My amps are doing it with no apparent issues


----------



## Horsemanwill (Jun 1, 2008)

i run my ID Q1200.1 @ 1 ohm have ben since i got it. never had any issues and everyone that hears my system says it sounds great


----------



## Jonny Hotnuts (Mar 15, 2011)

Frank, I remember back in the day there were few amps that could run 1ohm and all were designed for comps so I get where you are coming from. 

Its already been hashed out that its no problem for amps that are designed for it.....

For a suggestion in a 1ohm stable amp between 1-1.5K????
I would HIGHLY recommend the Audison LRx 1.1K. (1100 watts at 13.8v @ 1ohm) I got mine for 750$, and while its true you can buy the same watts cheaper it is not china made, has some really nice features and will say it should hold its resale value better then many of the lower end amps being pumped out by the millions. 


Good luck with whatever you choose. 

~JH


----------



## envisionelec (Dec 14, 2005)

cubdenno said:


> I have a SAZ1000d (Sundown 1000 watt at 1 ohm sitting on a shelf.) a JBL GTO14001 (1200 watts at 4 ohm 1500 at 2 ohms) and if you could do it quick, a Sundown SAZ1500D ([email protected]) ohm i would be willing to loan you to test. I have seen the SAZ1500 run at .35 DCR or something stupid at a SPL meet. with rise it was around 1.2 ohms.


My main point is I don't have the time. I can buy any of these or test them...it's just not a high priority.

Note that I didn't say anything about amps not working/staying cool/what-have-you. I said it's not a good idea and not as efficient if you have the choice.

I have also run 1 ohm loads, knowing full well that my amp was A) not designed for it and B) probably not delivering its full potential. I can repair any amplifier, so it didn't matter to me if I blew it up (it never did). My choice was based solely on what I could afford at the time. I had the chance to buy two, 2 ohm Solobarics and did not want to series wire them to the mono channel of an Xtant 3300c. However it was very stressful to the filter caps and they did need replacement shortly thereafter.

minbari - I'm not talking about speaker connection losses. I already explained my point about copper and parasitic losses which are much more important to the design than someone not screwing the terminals down tightly.


----------



## ZAKOH (Nov 26, 2010)

who does it?

Kids who think that you have to provide 1 to 2kilowatts to multiple subwoofers to be cool..


----------



## chad (Jun 30, 2005)

winning


----------



## minbari (Mar 3, 2011)

1-2kwatts really has nothing to do with what ohm you run things at. people were running 2kwatts in cars in the late 80's when I got into car audio, they were just doing it at 4 ohms with massive class A/Bs.

I think a couple things have happened:

1) amplifier companies have gotten lazy. to get 1000 watts output of a 1ohm stable amplifier you need roughly 32V. to get that same 1000watts out of a 4ohm amplifier you need 64V. to move the 12V dc in your car from 12V to 64V takes alot more powersupply than it does to only move it to 32V. and this has nothing to do with amplifier class. they could make 4 or 2 ohm stable class D just as Class A/B.

2) people dont want to pay $700-800 for a 900watt amplifier when they can get a 2200 watt amplifier for $400. its all about perception, and people perceive a better value, even if it isnt.

3) people have this idea that "ohms" are directly linked to how much wattage an amplifier will put out. that there is no way that a 2000 watt amplifier that is 4 ohm stable could put out nearly as much power as a 2000 watt amplifier that is 1 ohm stable...........its just marketing ploys. wattage is wattage and a lower impedance doesnt mean it will put out less.


----------



## integra9023 (Dec 12, 2009)

If you are looking for an amplifier that is fairly small and packs a big punch check out a Mmats 600.1D. I just used it in an installation under a seat in a 2007 Denali Truck. That bad boy is waaaay underrated and it is 1 ohm stable. I have also heard they will play at .5 ohms just never tested myself. I also have used a Massive Nano amplifier. Those are pretty good and 1 ohm stable as well!


Robert, GP Customs
gp customs | automobile and commercial window tinting | car audio and stereo sales service installation | lincoln nebraska
facebook.com/gpcustoms


----------



## cubdenno (Nov 10, 2007)

ZAKOH said:


> who does it?
> 
> Kids who think that you have to provide 1 to 2kilowatts to multiple subwoofers to be cool..


Or 40 year olds that want the output out of their single sub. I am the opposite of cool. 

So it would be politically acceptable to run a 1500 watt into a 4 ohm load amp?

How big is that going to be? How much more is that going to cost me?

Honestly who cares. If the sonic difference is pretty much inaudible on subs what does it matter. I have tried the apples to apples as close as I could and didn't hear a difference (again. My opinion on my set up. You may not like my setup!)

oooh found one! 
Rockford Fosgate T2500-1bdCP Power Series mono sub amplifier — 2,500 watts RMS x 1 at 2 ohms at Crutchfield.com

Kinda big. and wayyyyy outa my budget. I paid 350 bucks for my amplifier that has been running great for 4 years.


----------



## cubdenno (Nov 10, 2007)

envisionelec said:


> My main point is I don't have the time. I can buy any of these or test them...it's just not a high priority.
> 
> Note that I didn't say anything about amps not working/staying cool/what-have-you. I said it's not a good idea and not as efficient if you have the choice.
> 
> ...


Was just offering. Hell you are close enough it would be a reason to have a beer and learn something on my part
I get that they are not as efficient in the lower ohm loads. But a Class D at a 1 ohm load is still more efficient than a class A/B or hell in some cases a Class G/H. 

again, if you take into account the *chance* that it may shorten the lifespan, and it fits your space and budget, get the amp that puts out the power you want in the load you have if it will run it.


----------



## ellocojorge (Sep 30, 2009)

Frank Drebin said:


> Great news!
> 
> So, suggestions on properly designed amps? Looking at 1000-1.5k RMS @ 1 ohm.


Jbl bpx1100 can produce the power you are looking for at 1 and 4 ohms, i have one for sale 

Sent from my LG-MS910 using Tapatalk


----------

