2 ohm or not 2 ohm

Well enough Shakespeare, and on with my question... I was wondering if this is a myth or has some truth to it. My amp, Fosgate 1500.1bd can be run at either 2 ohm, or 4 ohm. Now, I have heard from 'round the way that i can run it at 4 ohm, and it will be easier on my amp, like not running it to hard. This didnt sound very scientific and the guy didnt explain any further. Im far from being wealthy and also supporting my child, so I would like to keep my amp in the best condition as possible so it will last, so was this guy accurate? If so, why is that the case? As far as i can tell, if I follow directions and use my amp the way it is designed, then either way it should not have a problem. I dont know, so any insight here would be great! Thanks

if you run the amp at 4 ohms, then you will only be getting half the power that it is capable of producing.  i dont see any good reason to purchase an amp and only get half the power from it. (unless the speakers that you are connecting to it cant handle the power)

rockford is a good brand of amp, if they say its stable to 2 ohms, then i wouldnt worry about running it that way.

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I actually have that problem, to much power for my wallet to get subs that can handle 3000 watts. So I might run them at 4 ohms anyways, but my local shop said this to me, and I wanted to know if they were right or talking outta there arse.

what sub(s) do you have? 

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Ohms law.  Power = (current squared) times resistance.  At a given power level, a lower resistance will require higher current.  For 100 watts, let's say, a 2-ohm load will draw about 7 amps, and a 4-ohm load will draw about 5 amps.  Since it is amps that create heat inside an amplifier, more amps = more heat.  More heat = more stress on the components and shorter life.  So, in general, higher ohm loads will enable an amplifier to operate at lower temperatures and the amp will last longer.

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thats all well and good, but amplifiers are designed to give off heat.  should i ditch my 4 ohm speakers, and go with 8 ohms, just because my amp will run a bit cooler?  if an amp is designed to run at a given load, then run it that way.  if its a quality amp, and you have it installed properly, then you wont have any issues.

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While I agree that this setup should have no problem runnign at 2 ohms that does not necessarily mean it must be done a 4 ohm load will cause the amp to run cooler and possibly extend the longevity of it, but it really depends on the power handling and the impedance of the woofer(s). I believe it's been used on this forum before but just because you have a car capable of going 200mph does not mean you must drive at 200mph everywhere you go. Just my 2 cents.

--->Richard

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2008 Scion xB
Pioneer AVIC-D3
RF 3Sixty.2 sound processor
Stock speakers (for now ;))

duct tape do you have a problem?  I simply answered the question which you did not.

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duct tape wrote:

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if you run the amp at 4 ohms, then you will only be getting half the power that it is capable of producing.  i dont see any good reason to purchase an amp and only get half the power from it. (unless the speakers that you are connecting to it cant handle the power)

thats all well and good, but amplifiers are designed to give off heat.  should i ditch my 4 ohm speakers, and go with 8 ohms, just because my amp will run a bit cooler?  if an amp is designed to run at a given load, then run it that way.  if its a quality amp, and you have it installed properly, then you wont have any issues.

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Do you drive your vehicle all the time at it's top speed?  If not, do you feel you were ripped off because you aren't using it at it's designed speed?

Just because an amplifier is stable down to a lower impedance doesn't mean you have to run it that low.  An amplifier is designed to run any impedance down to a certain point, not to run only at the lowest rated impedance.    Also, did you actually measure your speakers impedance to make sure their nominal impedance was 4 ohms?  After all if they were designed with say a 3.8 ohm DCR instead of 3.2 ohms then you aren't running the amplifier at an actual 4 ohms nominal load.

so because i have a different point of view, that means that i have a problem?     is debating not allowed in this forum? must we all agree?

my point is...why would you pay money for a sub amp, then run it at 4 ohms, when it is designed to give full power at 2 ohms?  seems like a waste of money to me.   if you guys like to use half of your amp's potential, great, go for it, its your money

since you guys like to talk about cars so much....would you purchase a car that could hold 8 people, and only fill it up with 4 people?  that would be a waste of money, now wouldnt it?

i am also interested in what subs he has....i dont see how he would have a choice between 2 or 4 ohms, if he has already purchased the subs.

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duct tape wrote:

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my point is...why would you pay money for a sub amp, then run it at 4 ohms, when it is designed to give full power at 2 ohms?  seems like a waste of money to me.   if you guys like to use half of your amp's potential, great, go for it, its your money

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So you think that someone is wasting money if they don't load down their amplifier to it's lowest stable impedance?  So what do you say to people with a single 4 ohm sub?  After all 4 ohm stable sub amps are few and far between.  Do you require them to go out and purchase another sub to drop the impedance, or even swap subs?  Now who is wasting money?

duct tape wrote:

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since you guys like to talk about cars so much....would you purchase a car that could hold 8 people, and only fill it up with 4 people?  that would be a waste of money, now wouldnt it?

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Are you familiar with America's obsession with the SUV?  Do you really think that all those SUV's on the road are owned by families who are able to fill the seats up?  Heck, my car usually only has one person in it and it has 4 seats. 

There are advantages to running an amplifier at a higher impedance.  You will have less heat as Dyohn already mentioned, lower distortion, and less stress on the electrical system. 

Yes I should clarify the speakers situation.
I actually havent bought any speakers yet, but I believe I am going to buy two 15" JBL GTO1504D, which is the dual 4ohm sub, they also have the same thing bout offered as dual 2ohm.
   Now the reason I was thinking running at 4 ohm off one of my amps is because 4 ohm would put out 750rms from the amp.
   The subs are rated at 300rms, 1200 peak, so I wouldnt have a need to run it at 2 ohm putting out twice as much power.
Unless I buy three, or four maybe, of these 15" JBL subs, then 2 ohm would make more sense i guess.
I just wish I could afford some subs that could handle all my 3000 watts, oh well patience is a virtue.

One Rockford Fosgate 1500.1bd amp kicks serious ***!
I hade it hooked up from the repair shop yesterday to two 12" JL Audio W3 subs in a ported box at the speaker shop hooked up at 2 ohms, it when the sales guy was messing around with the gain, I could clearly hear a couple of times the amp putting out to much power for those poor subs to handle, and distortion city! Just wanted to share that cus Im very impressed with this product, and would recommend this amp to anyone needing plenty of power!

I also agree with that statement of running cooler is better, and keeps distortion away better, and Im all about distortion free music.
But I also would like to be able to use all available power I have, bet I could level a house if I had the money to drop on some higher end/price subs.

Steven Kephart wrote:

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So you think that someone is wasting money if they don't load down their amplifier to it's lowest stable impedance?  So what do you say to people with a single 4 ohm sub?  After all 4 ohm stable sub amps are few and far between.  Do you require them to go out and purchase another sub to drop the impedance, or even swap subs?  Now who is wasting money?

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if he has the equipment, thats one thing.  but i would never sell a customer a mono subamp that is stable to 2 or 1 ohm, and then sell a single 4 ohm subwoofer, unless the customer planned on buying another sub at a later date.  that would be a waste of an amp. 

Steven Kephart wrote:

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Are you familiar with America's obsession with the SUV?  Do you really think that all those SUV's on the road are owned by families who are able to fill the seats up?  Heck, my car usually only has one person in it and it has 4 seats. 

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i'm very familiar with that obsession....it sounds like a mismatch to me, just like a 4 ohm sub on a mono sub amp.....

Steven Kephart wrote:

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There are advantages to running an amplifier at a higher impedance.  You will have less heat as Dyohn already mentioned, lower distortion, and less stress on the electrical system. 

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if you can tell on a mono sub amp, the distortion difference between a 2 and 4 ohm load, then you must have some very fine tuned ears. i understand that you will get less heat, but if the amp is designed for a lower impedance, then it should not be an issue.  if you want less stress on your electrical system, then dont buy an amp that is more than you need anyways.   

i really find it amazing that you guys cant understand my logic in this...is it because i dont have a thousand posts here and a bunch of icons next to my name, that you guys feel that my opinion is wrong?  i guarantee you, the rest of the car audio world is with me on this one....

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Duct tape no one said you were wrong.  You just simply did not answer the question, and now you are getting belligerent about it.  Chill out.

I completely disagree with you, however, that it is somehow a "waste" to not run your gear full out all the time.  It is simply a matter of choice and trade-offs.  If someone wants the highest SQ possible from their gear and they are concerned about longevity, using higher impedance loads is a good thing to do.  If someone simply wants things to get as loud as possible, the lowest impedance load is the way to go.  Different strokes is all it is.

Me, I have used a DVC 4-ohm sub specifically so I can operate at 8-ohms many times.  In fact right now I have two 4-ohm SVC subs in series for an 8-ohm load in my car.  It's all about keeping things clean, doing what's best for the amp, and balancing the overall acoustic output of a system to create the effect I want in my vehicle. 

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duct tape, no one is saying that you are wrong, but it DOES sound to me as if you are saying the WE are wrong, also, (and repeatedly) because we don't exactly agree with you. We DO encourage spirited debates here, you've been here long enough to have seen one or two, I'd bet, but we all respect everybody's opinions, we always have.

DYohn and Steven have both expressed the pros and cons of running an amplifer at higher vs. lower impedances. Here is really what it boils down to:

Lower impedance
Pros:
More power
Higher SPL

Cons:
More total heat
More distortion
Lower damping factor
Lower efficiency
Shortened electronics life

Higher impedance
Pros:
Less total heat
Less distortion
Higher damping factor
Higher efficiency
Longer electronics life

Cons:
Less power
Lowered SPL

Those are all concrete and PROVABLE differences, (with the possible exception of the damping factor thing...) and to my eyes, the higher impedance load seems to be the better choice. The difference in sheer SPL output in running a 4 ohm load, vs a 2 ohm load is ONLY 3dB, (which in a competition is a HUGE number, especially when winners go home with a .1dB advantage, but) in a daily driver, that won't be noticed as a loss; and really, the improved fidelity due to lowered distortion and improved control over the woofers will most likely be perceived as a substantial benefit.

The big one for me, (actually the big two, the first being the distortion thing... oh, and the damping factor thing. ) is the efficiency. For a lower impedance, there is MORE HEAT PROPORTIONATELY produced for a given output. This means that if an amplifier is 60% efficient at 4 ohms, (a typical Class AB number) it could be as low as 50% efficient at 2 ohms. (Also a fairly typical number, in the case of Class AB) It doesn't maintain it's efficiency at all loads.    More proportionate stress on the electrical system... Less (or lower) efficiency is a bad thing. Class D amplifers suffer the SAME efficiency drop, although they DO start at a higher reference efficiency, true.

Even IF an amplifier is designed to run safely at a given load, a one degree rise in temperature will cause as much as a 25% reduction in total life of ANY electronic device, such as a transistor. Capacitors are even MORE sensitive to it; they're more like 50 to 60%. Doesn't it make even more sense to reduce the operating temperature of any electronic component, now? Obviously, the devices are RATED for such operating temperatures, but the rule above also applies for a REDUCTION of temperature. Run a device one degree COOLER, and it will last up to 25% LONGER... THERE'S your money savings!

You also mentioned that the entire car audio industry would agree with you. I personally take exception to that, and I can get you in contact with two engineers (ok, one engineer and one engineer intern ) at Harman International in Northridge, CA, that DO NOT disagree with me or the other accepted (and NOT wrong) views on this forum. I guarantee you, that I do not disagree with you, and I DO understand your logic, but it is NOT the only view, and we could throw that back at you as well...










(How's that? (And that person knows to whom I am referring...))

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

David, you must have still been in transit (or drooling on your new amps) when this discussion was going down.LOL.  As usual your argument was complete and correct. I, as a dealer in car audio for 26 years, agree 100%.

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There is no such thing as free installation!

I'm with Duct Tape with this one. He's simply trying to help the OP to get the most out of his amp. I don't know how anyone can preach to buy your amps and don't put it at the lowest impedance because the cons produced are yes, proveable, but most of the time it is inaudible and doesn't really make a difference. Hell, you're not even calculating everything else in his set up and you don't know how the OP's electrical system is. What's wrong with a little headroom and gains manipulation? Just curious, out of all the enthusiast and consumers in this money pit,  who's buying their sub amps to put it at higher impedance? Very little I would guess. And it's probably those same home audio guys who are buying $500 speakers wires to put it in their cars.

Oh BTW, people gotta stop bringing in other professionals to back their statement up. We have the same engineers saying to keep your RCA's and power wire separate. I pretty sure the majority installers know how questionable that logic is... when their guilty of doing that but yet to get noise. "Hey, I've been doing this for 20 years, I know what I'm doing." Yeah you could be doing it wrong for 20 years. LMAO!! :D

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USUC World Champion - Stock System Class, Super Street Division. Special Edition Bose 26 piece speaker system with enhanced ported tweeters. 89.2 db Legal, 89.6 db Outlaw

Get the most WHAT? Heat? Distortion? Short lived electrical components? Did you read the last post I put up?

Vestax, did you even bother to read all of the thread? You are now doing the same thing duct tape was doing, and basically telling us we are wrong. Are we, in fact, WRONG, or are you simply stating your opinion? I already said that he WASN'T wrong, yet here you come into the thread, and effectively say that we ARE wrong.

Headroom, at the expense of distortion and short-lived electronics is not a gain.

As DYohn asked (and answered) of duct tape, did you answer the question? No, in fact, he didn't. Now, I will ask the same of you: Did you actually answer the question? No, again...

I'll paraphrase the question AGAIN.

3000dclass wanted to know if there was any truth to the (potential) urban myth that running an amplifier with 4 ohms, instead of the maximum stable load of 2 ohms, is easier on the amplifier... We (DYohn, Steven, and I) all answered the question, (and even backed some of our answers with researchable, provable scientific, and hard facts) as to why it IS easier on the amplifier to run with a higher impedance.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

Right now I have an eD Nine.1 amp...stable down to 1 ohm but am running a SVC 8 ohm sub. I feel no waste in power or money.

haemphyst wrote:

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Get the most WHAT? Heat? Distortion? Short lived electrical components? Did you read the last post I put up?

Vestax, did you even bother to read all of the thread? You are now doing the same thing duct tape was doing, and basically telling us we are wrong. Are we, in fact, WRONG, or are you simply stating your opinion? I already said that he WASN'T wrong, yet here you come into the thread, and effectively say that we ARE wrong.

Headroom, at the expense of distortion and short-lived electronics is not a gain.

As DYohn asked (and answered) of duct tape, did you answer the question? No, in fact, he didn't. Now, I will ask the same of you: Did you actually answer the question? No, again...

I'll paraphrase the question AGAIN.

3000dclass wanted to know if there was any truth to the (potential) urban myth that running an amplifier with 4 ohms, instead of the maximum stable load of 2 ohms, is easier on the amplifier... We (DYohn, Steven, and I) all answered the question, (and even backed some of our answers with researchable, provable scientific, and hard facts) as to why it IS easier on the amplifier to run with a higher impedance.

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Okay you got me there haemphyst. You're right... I didn't really read the first question thoroughly. You guys are answering the question that the OP's asking. I apologize. I jumped the gun and saw a lot of bickering. LMAO!

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USUC World Champion - Stock System Class, Super Street Division. Special Edition Bose 26 piece speaker system with enhanced ported tweeters. 89.2 db Legal, 89.6 db Outlaw

Hey... an RF 1500.1bd is ONE ohm stable anyways! So, running 2ohm is conservative.

I ran my 10001bd at .67 ohms without even heating the amp up... I did however toast my alternator which is another story...

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'94 Ford Explorer / Kenwood KVT-815DVD / RF Power T1682C 6x8 (all doors) / RF Power T10001 / 12" Kicker L5 (x4) / Optima Yellow Top Battery

hustlin247, im not to sure if your right that the RF 1500.1bd actually is made to go down to one ohm. I never had the boxes for my amps, BUT, the stickers from the manufacturer on the back of the amps state only 4ohm w/750rms watts, and 2 ohm w/1500rms watts.
What would 1 ohm be then, 3000rms watts?

One of my RF 1500.1 stickers says I can bridge it, dunno why I would want to do that with a mono amp though...

If the amplifier power supply is "stiff" enough, it would be 3000 watts, but I doubt that it is. Fosgate hasn't ever been a really high CURRENT amplifier.

2000-2250 might be a fairly safe guess, but as you say, it's probably not rated at that load anyway.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

There are more aspects to car audio than max SPL or power utilization.

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There's head units that can show pictures of dolphins and stuff!

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There is no such thing as free installation!

Oh good sirs,

I assure that your RF Power 1500.1 bd is in fact 1ohm stable.

All RF's current POWER series monoblock amps are 1ohm stable and this data is straight from Rockford Fosgate.

Your amp is rated 1500 watts x 1 @ 1 ohm. Check it out: https://www.rockfordfosgate.com/products/product_details.asp?cat_id=2&series_id=104&family_id=105&item_id=107999&locale=en_US&p_status=

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'94 Ford Explorer / Kenwood KVT-815DVD / RF Power T1682C 6x8 (all doors) / RF Power T10001 / 12" Kicker L5 (x4) / Optima Yellow Top Battery

Uh oh. The sticker on your amp says 1500 x 1 @ 2ohm?

Is this amp not from their current series of amps? According to RF's website... well... you see my other post...

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'94 Ford Explorer / Kenwood KVT-815DVD / RF Power T1682C 6x8 (all doors) / RF Power T10001 / 12" Kicker L5 (x4) / Optima Yellow Top Battery

damn...check that efficiency, drops around 18% from 4 ohms to 1 ohm


86% @ 4-Ohm
85% @ 2-Ohm
68% @ 1-Ohm

aznboi3644 wrote:

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damn...check that efficiency, drops around 18% from 4 ohms to 1 ohm


86% @ 4-Ohm
85% @ 2-Ohm
68% @ 1-Ohm

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The prosecution rests, your honor.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

3000d...

i'm with some of the "older" guys on here. I'm notorious for buying an amplifier rated well beyond what my speakers are capable of handling, then simply running it at lower draws. It is less stressful on the equipment...

it's like going to the gym, you can press 200 pounds many less times than you can 20.

Go 4!!!

-----and by "older" I mean people who i've seen post ALOT on here, and have individually talked to before... I know you know you're stuff.

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Greed is for amateurs.

Disorder,chaos,anarchy now THAT is fun!!