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perfecxionX
05-20-2007, 03:49 PM
why is it that so few manufacturers make svc2ohm components? so many a/b amps are 2 ohm stable, why are almost all comp speakers svc 4?

CRAZYCORNUTS18
05-20-2007, 03:59 PM
infinitys new kappas are all 2 ohm

IgnoreMe
05-20-2007, 04:19 PM
yes not to mention 2 ohm speakers would save people a lot of money in the long run.

ngsm13
05-20-2007, 04:20 PM
Apparently you are unaware of that when you take sensitivity/efficiency into account... they'res really little to no difference in using 4ohm and less power versus 2ohm and more power...

:fyi:

nG

Rich B
05-20-2007, 04:22 PM
Before they sold out....I mean were bought out........Orion made some 2ohm 6.5 mids, which you can still buy on eBay here-

2ohm RARE! Orion HCCA Millennium Edition Mids! 6.5" NEW
http://cgi.ebay.com/2ohm-RARE-Orion-HCCA-Millennium-Edition-Mids-6-5-NEW_W0QQitemZ9740885487QQihZ008QQcategoryZ32819QQt cZphotoQQcmdZViewItem

Hintzyboy
05-20-2007, 04:23 PM
yes not to mention 2 ohm speakers would save people a lot of money in the long run.

How so?

IgnoreMe
05-20-2007, 04:33 PM
How so?

cause its easier to get the proper ammount of power @ 2 ohms than 4. for instance you got speakers that need 200 watts. the same brand amp that puts out 200 watts @ 4 ohms will cost more than the one that puts out the 200 watts @ 2 ohms. same concept with running subwoofers at 1 ohm and such, because any amp that does good power at 4 ohms costs an arm and a leg. just my .02

make sense? dont know if i explained that very well :crap:

ngsm13
05-20-2007, 04:53 PM
Apparently people ignored post #4.

:rolleyes:

nG

IgnoreMe
05-20-2007, 05:19 PM
Apparently people ignored post #4.

:rolleyes:

nG

i didnt ignore it, i just dont understand it.

edit: ohhh now i get it. i thought you were talkin about something else. i THINK you misunderstood what he was trying to get at...or maybe i did. to me i believe your saying there is not difference between a 2 ohm and 4 ohm speaker if they both have the same wattage...correct?

what im saying is that you can get amps that put out good power at two ohms for cheaper than you can get amps that put out the same power at 4 ohms...which is why im arguing that i think 2 ohm speakers would save people money

ngsm13
05-20-2007, 05:44 PM
No, you must misunderstand.

A 4 ohm driver given 100 watts will have about the same output as a 2 ohm driver given 200 watts. This is assuming everything else is equal. This relates to sensitivity, not power handling.

More technical reading:

http://www.diymobileaudio.com/forum/showthread.php?t=31

nG

profundus-sanus
05-20-2007, 05:58 PM
lower impedance hurts thermal power handling as well...

they would have to make the unit beefier to handle the increased in current. about 40% more, roughly...

IgnoreMe
05-20-2007, 06:32 PM
No, you must misunderstand.

A 4 ohm driver given 100 watts will have about the same output as a 2 ohm driver given 200 watts. This is assuming everything else is equal. This relates to sensitivity, not power handling.

More technical reading:

http://www.diymobileaudio.com/forum/showthread.php?t=31

nG

dont have time to read the thread right now. but will later.

im not understanding though. so what your saying is that by nature a 2 ohm driver is less sensitive than a 4 ohm driver and therefore the outputs will be relativly similar?

ngsm13
05-20-2007, 07:02 PM
dont have time to read the thread right now. but will later.

im not understanding though. so what your saying is that by nature a 2 ohm driver is less sensitive than a 4 ohm driver and therefore the outputs will be relativly similar?

Yes.

nG

Igno
05-20-2007, 07:06 PM
No, you must misunderstand.

A 4 ohm driver given 100 watts will have about the same output as a 2 ohm driver given 200 watts. This is assuming everything else is equal. This relates to sensitivity, not power handling.

More technical reading:

http://www.diymobileaudio.com/forum/showthread.php?t=31

nG


I understand better thx for the link

alphakenny1
05-20-2007, 07:11 PM
ng is right. the lower the impedance, the less efficient the speaker is. its due to the length of the wire in the voice coil. more length of wire to the voice coil will result to the speaker being more efficient. thats why when i was running a pair of Peerless SLS 8" (8 ohm speakers), getting about 150 x 2 @ 4 ohms so getting 75 watts, they absolutely pounded. Output was unreal. so for me, i will not hesitate to run an 8 ohm speaker in my car due to the speaker being much more efficient. you guys should all read that article though.

MiniVanMan
05-20-2007, 07:21 PM
Also, take into account that even though an amp may have a rating 0f 200 x 2 @ 2 ohms, and 100 x2 @ 4 ohms it never works that way. The 200 x2 @ 2 ohms may accurate but to assume it's doubled of it's 4 ohm rating is wrong. An amp would need an efficiency rating of 100% in order to do that. So in actuality, the higher the impedance, the more watts you get per amp of current. Your amp runs cooler and more efficient.

///M5
05-20-2007, 07:43 PM
I'd argue that making 4 ohm speakers is sort of a joke these days as well, there is really no reason to not use 8 ohm drivers in your car.

Hintzyboy
05-20-2007, 09:02 PM
Only cost benefit I can see is for the manufacturers. Lower impedence means less money spent on the copper/aluminum for the VCs. With copper prices going up, this might have a small trickle-down effect that saves the consumer a bit of money, but I doubt it.

MiniVanMan
05-20-2007, 09:56 PM
Only cost benefit I can see is for the manufacturers. Lower impedence means less money spent on the copper/aluminum for the VCs. With copper prices going up, this might have a small trickle-down effect that saves the consumer a bit of money, but I doubt it.

Yeah, that may be the case, but overall, from a marketing standpoint car audio is about power. The more power you can advertise the more you can sell. It has nothing to do with reality.

Your average consumer for car audio will equate more power from an amp to greater volume. Marketing departments see no need to change this way of thinking. It may very well be for the reasons you stated Hintz. But mostly, the myth is already in place, so it's more work than a marketing department is willing to do to change that myth.

Hell marketing departments aren't filled with engineers. So they most likely don't know the difference either.

ngsm13
05-20-2007, 09:58 PM
Indeed sir. Indeed.

nG

IgnoreMe
05-21-2007, 01:49 AM
****. this **** just blew my mind haha. learn something everyday. but efficiency can only go so far no? i mean after a while your just gonna need more power right?

CaliforniabOY5
05-21-2007, 02:37 AM
Holy Crap! I learned something new. Thanks Ng, even thou i know you despise me for some reason :confused:

MiniVanMan
05-21-2007, 02:51 AM
****. this **** just blew my mind haha. learn something everyday. but efficiency can only go so far no? i mean after a while your just gonna need more power right?

Yeah, there's a point where you need to overcome the mechanical properties of the driver. For example the weight of cone. There's a spec called Mms that's a variable within the equation for determining sensitivity. It's basically a detractor due to the mechanical properties of the driver.

So, I'd venture to say, than in a lot of situations, throwing 20 watts into an 8 ohm driver might not get the driver to full excursion as opposed to throwing 40 watts to the same driver but with a 4 ohm coil instead.

After about 50 watts @ 8 ohms, you'll notice very little difference between an 8 ohm driver and a 4 ohm driver driven off the same amp, given the speakers are similar (i.e. Dayton RS180-4, and RS180-8)

Warbleed
05-21-2007, 04:26 AM
It's a bit of a misnomer to call an 8 ohm driver more efficient than a 4 ohm driver based solely on that information. We can say that's true to an extent if we are holding coil material as a constant, but that's not always the case. For instance if we were comparing a 4 ohm driver to an 8 ohm driver, and the 4 ohm driver is using an aluminum coil and the 8 ohm driver is using a copper coil, the 8 ohm driver could actually be less efficient, if the Mms is low enough on the 4 ohm driver (remember, the two factors in Efficiency are BL and Mms). Now obviously if we're comparing a driver that just offers different impedances, this wouldn't happen, but it certainly could for many other comparisons.

I wouldn't focus on impedance at all when selecting a driver. Realistically, all you need is a driver which is capable of yielding enough output from your amplifier to provide your needs, so realistically speaking, impedance is not relevant, if that requirement is being met.

People focus far too much on having X amount of power available, without bothering to consider whether or not they actually USE that power.

I'm willing to bet a large majority of people would be quite surprised at how little power they actually typically send to their front stage.

Nothing in npdang's article is untrue, but some of the conclusions people are making aren't really justified/correct.

Gary S
05-21-2007, 06:58 AM
Watts are cheap... buy a bigger amplifier and quit your whining :beathors:

elementxero
05-21-2007, 07:32 AM
Interesting crap, never knew any of this.

Hintzyboy
05-21-2007, 12:35 PM
I did. Only because I made myself look like a douchebag in a similar thread and got thoroughly schooled.:graduate:

MiniVanMan
05-21-2007, 02:34 PM
It's a bit of a misnomer to call an 8 ohm driver more efficient than a 4 ohm driver based solely on that information. We can say that's true to an extent if we are holding coil material as a constant, but that's not always the case. For instance if we were comparing a 4 ohm driver to an 8 ohm driver, and the 4 ohm driver is using an aluminum coil and the 8 ohm driver is using a copper coil, the 8 ohm driver could actually be less efficient, if the Mms is low enough on the 4 ohm driver (remember, the two factors in Efficiency are BL and Mms). Now obviously if we're comparing a driver that just offers different impedances, this wouldn't happen, but it certainly could for many other comparisons.

I wouldn't focus on impedance at all when selecting a driver. Realistically, all you need is a driver which is capable of yielding enough output from your amplifier to provide your needs, so realistically speaking, impedance is not relevant, if that requirement is being met.

People focus far too much on having X amount of power available, without bothering to consider whether or not they actually USE that power.

I'm willing to bet a large majority of people would be quite surprised at how little power they actually typically send to their front stage.

Nothing in npdang's article is untrue, but some of the conclusions people are making aren't really justified/correct.

Yes, but if you add Hoffman's Law into the equation, you start to see the sacrifices you need to make in order to achieve the higher sensitivity, (i.e. low end capability).

So while, it's a rough generalization to say that an 8 ohm is more sensitive than a 4 ohm, there are many other variables that come into play that makes the overall implementation of an higher impedance driver a little more sensitive, and again, more efficient watt to amps.

I think the point that everybody is trying to make is that using higher impedance drivers is just fine, and in the end can be beneficial.

iamamp3pimp
05-21-2007, 02:42 PM
i agree.

i felt the same as the OP at first, until i learned by reading what npdang said.

i put some daytons in my car 98 ohm) and the output was unreal...

samson
05-21-2007, 03:37 PM
I've switched from an 8ohm to a 4ohm sub (same brand same model). Output was NOT the same. I've switched from 8ohm to 6ohm at my home, output was NOT the same. I can't tell you why in any technical sense, but that link is a bunch of malarky.

alphakenny1
05-21-2007, 03:53 PM
I've switched from an 8ohm to a 4ohm sub (same brand same model). Output was NOT the same. I've switched from 8ohm to 6ohm at my home, output was NOT the same. I can't tell you why in any technical sense, but that link is a bunch of malarky.

thumbs up for proving your point. that was such a controlled experiment, it certainly proves by lowering the impedance changes the output! way to go! :rolleyes:

also we aren't talking bout subs here buddy, we are talking about mids.

samson
05-21-2007, 03:55 PM
thumbs up for proving your point :rolleyes:

If you want to believe everything you read on some forum, that's certainly your right. I'll trust my ears. btw - The home speakers weren't subs. I got quite a bit more output.

And sorry for trying to share my real world experience instead of linking some other forum thread. Sheesh.

alphakenny1
05-21-2007, 04:01 PM
If you want to believe everything you read on some forum, that's certainly your right. I'll trust my ears.

oh please, the guy was just explaining why its okay to use an 8 ohm driver. there are things in that article that CANNOT be disputed. the equation of efficiency, cannot be disputed. things called FACTS. you shoulda listened to my car when i had some peerless SLS (8 ohm midbasses) in my car. getting around 75 watts each and absolutely pounded. your lil argument is clearly not valid as are you doing a direct swap of the same speaker but lower impedance or just two different subs? if two different subs, then again, not valid as the speaker design is probably the factor in difference in output ;).

samson
05-21-2007, 04:05 PM
I'm telling you there is more to it.

alphakenny1
05-21-2007, 04:08 PM
i have no problem people sharing their real world experiences but when you go and say the article is bs or whatever the hell malarky means and have no evidence or facts behind it, thats when i have a problem.

samson
05-21-2007, 04:11 PM
i have no problem people sharing their real world experiences but when you go and say the article is bs or whatever the hell malarky means and have no evidence or facts behind it, thats when i have a problem.

Real world experience is not evidence but linking somebody else's opinion on a forum is? Sure body. Case and point right there. My apologies. :rolleyes:

alphakenny1
05-21-2007, 04:16 PM
Real world experience is not evidence but linking somebody else's opinion on a forum is? Sure body. Case and point right there. My apologies. :rolleyes:

like i said, how is the article "malarky?" where's the evidence that it is "marlarky?" oh its because you heard something different. then why? why did you hear something different? please explain me how does the equation of efficiency invalid in your case? like i said show some FACTS that the article is "malarky" and then we'll have a real argument here. also like i said you are comparing apples to oranges. you comparing subs when we are talking about mids here. please.....

samson
05-21-2007, 05:13 PM
"Efficiency = ( B^2 * L^2 ) / ( R * Sd^2 * Mms^2 )

B = magnetic field strength
L = length of wire
R = resistance
Sd = surface area
Mms = mass

So for your 8 ohm voice coil, using the same wire as a 4 ohm voice coil, you would need twice the L or length to get an 8 ohm impedance. That makes sense doesn't it? A longer wire will have more resistance. Now, looking at the formula above, doubling L actually causes your efficiency to rise, even though the impedance also rises. So in this very oversimplified example, raising the impedance actually causes efficiency to go up and lowering the impedance actually causes a loss of efficiency."


Not sure but I think he's overlooking mass. As a denominator, it would at least partially offset the his length of wire. Seems like more wire in the voice coil = more mass you have to move.

ngsm13
05-21-2007, 06:08 PM
You are an r-tard.

nG

samson
05-21-2007, 07:37 PM
Frickin kids. :rolleyes:

ngsm13
05-21-2007, 07:41 PM
Like you?

nG

samson
05-21-2007, 07:45 PM
Does 13 represent your age or IQ?

ngsm13
05-21-2007, 08:37 PM
Neither.

kthnx.

nG

MiniVanMan
05-21-2007, 11:18 PM
"Efficiency = ( B^2 * L^2 ) / ( R * Sd^2 * Mms^2 )

B = magnetic field strength
L = length of wire
R = resistance
Sd = surface area
Mms = mass


Not sure but I think he's overlooking mass. As a denominator, it would at least partially offset the his length of wire. Seems like more wire in the voice coil = more mass you have to move.

Would you care to explain what Mms is then? How about mechanical Q (Qms). Mass is taken into the equation. And you are correct it is a detractor, as stated in the above formula.

Npdang even says it's a very simplified explanation. Fact is though, that it's still accurate. You're calling out one of the most respected members of the car audio community. He's also well known in home audio circles. He knows his stuff. If you want to challenge him, then by all means do so. I'd like to see it. He's very professional, and very approachable. He also deals in facts, and not opinion, unless you're talking subjective sound quality analysis. He's also the founder of that forum. The sub on the front page is designed by him, and quite a piece of equipment.

So, you have yet to prove to any of us "kids" that you have objective, factual data to dispute what he states. Which, remember he states as "can be beneficial", not will be beneficial.

You haven't provided any data to support your conclusions. Now I will admit, again, that it's a very simplified explanation that we're giving. If you have some real world experience that produces varying results, then great. I have real world experience that reinforce Npdang's statements.

Also, in the case of subs, you have a lot more mass to move. More power can equate to higher output over a moderately more efficient sub with a higher impedance. Also, we're talking about low frequency response. Hoffman's Law has a whole lot to do with it.

You stated same sub. Is it the same sub, in the same box, ran off the same amp, just a different impedance? There are so many variables that can affect how a sub performs beyond just impedance and power supplied.

Comparing two different home audio setups, (6 ohm to an 8 ohm), you once again, haven't supplied us with models, or any other data than "the 6 ohm was louder". Once again, low extension, drivers, box alignment, and so many other variables that you haven't stated need to be taken into account.

I'm not disputing that one was louder than the other. There is so much else that needs to go into that statement before you can objectively debunk anything Npdang has said.

You won't make many friends by trying to trash Npdang. Like I said, he's extremely well respected, and one of the most approachable people in car audio. He is without ego, and the elite attitude that comes with many of the big shots in car audio.

So, again, I ask you to really challenge his statements, from a technical standpoint.

helotaxi
05-22-2007, 09:00 AM
There's a whole lot more to it than any of these generalizations take into account.

You can't categorically say that lower impedance drivers are less efficient. In the example of the ID Chameloens they have the same efficiency measured at 1W*m (rather than 2.83V*1m as most speakers are rated.).

Secondly. Take the equation and look at the relationship between the different variables. There is an exponentional relation between the length of wire in the gap and the resisitance of that wire. If you double the length of wire, you will double the resistance but increase the BL product by 4x. Since you don't also double the Mms (there's way more than the coil involved in the moving mass) you will get an increase in driver efficiency.

Third, you can't make a simple half the wire double the wire comparison and get a valid result. If you did that, the 8 ohm dirver would flat walk all over the 4 ohm version. The 4 ohm version would see more current for a given wattage with less wire in the coil to shed the heat. It would therefore have lower thermal power handling and be less efficient.

There has to be a change in the diameter of the coil wire in addition to the length to keep power handling about the same. That makes for an increase in the L portion but an increase in the Mms as well.

Samson, real world though your example may have been scientific it wasn't even close.

CobaltKicker
05-22-2007, 09:07 AM
<~~~ I have one 06 Kicker 12L7 DVC 2-ohm Wired in 4-ohm to my amp(Kicker 06ZX850.2) in 4-ohm load RMS @ 850 x 1 channel. ****, you should hear it :)....but I am pretty sure you mentioned Single Voice Coil?....**** the singles...but nothing is different with a 4-ohm DVC and a 2-ohm DVC besides wiring capabilities and amp compatibilities. At least that is my experience....but I am sure I will be bad-mouthed in 1....2....3....4.....

joetama
05-22-2007, 09:44 AM
I think the basic point was that you have to look at the sensitivity of the driver when selecting one. You can't just look to see if t is 4 ohms, 8 ohms, or 2 ohms.

Comparing the sensitivity is always a GREAT rule of thumb... :fyi:

elementxero
05-22-2007, 08:22 PM
<~~~ I have one 06 Kicker 12L7 DVC 2-ohm Wired in 4-ohm to my amp(Kicker 06ZX850.2) in 4-ohm load RMS @ 850 x 1 channel. ****, you should hear it :)....but I am pretty sure you mentioned Single Voice Coil?....**** the singles...but nothing is different with a 4-ohm DVC and a 2-ohm DVC besides wiring capabilities and amp compatibilities. At least that is my experience....but I am sure I will be bad-mouthed in 1....2....3....4.....

Not to bust balls, but I believe it's traditional to count DOWN to an event.




edit- Actually of ******* course this was to bust balls.

helotaxi
05-22-2007, 08:36 PM
I think the basic point was that you have to look at the sensitivity of the driver when selecting one. You can't just look to see if t is 4 ohms, 8 ohms, or 2 ohms.

Comparing the sensitivity is always a GREAT rule of thumb... :fyi:

But you have to make sure that you compare apples to apples when you do compare sensitivities. Most sensitivity specs are 2.83V*1m which is 1 watt for an 8 ohm driver but 2 and 4 watts for 4 and 2 ohm drivers respectively. With that a 4 ohm driver that is 2dB more sensitive than an 8 ohm driver will acutually be less sensitive watt for watt than the 8 ohm driver.

joetama
05-22-2007, 11:31 PM
Very true...

I guess that I always try to match my sensitivities.

Except when running active. Then it really doesn't matter that much because you have a gain knob... ;)

bobbeyo
06-03-2007, 02:12 PM
So whats the difference in a set of 4 ohm or 2 ohm components if they have the same sensitivity.

MiniVanMan
06-03-2007, 02:26 PM
Could be a number of factors.

When looking at sensitivities of component sets you have to be VERY wary of how the sensitivity is measured.

First is, and I've seen this a lot is the manufacturer uses the most sensitive driver, the tweeter to measure the sensitivity of the set. So, you have a set that's rated 93db @ 1w/1m. Well, they're probably using the tweeter. Not at all accurate.

Another is, when you take two drivers of the same diameter, and same impedance, but one is 3 db more sensitive, it's a good bet that it will not have the low end thump of the driver that's 3 db less. Hoffman's Law VERY, VERY simply stated. Give me a break guys. Go to partsexpress and take a look at the sensitivities of an 8", 8 ohm home audio driver, and an 8", 8 ohm pro audio driver. You'll notice the pro-audio driver is much more sensitive in most cases. That pro-audio driver will not have the same low end attack though.

There are a ton of other other variables as well. Unfortunately, we exist in a market where truth is subjective, and manufacturers can play with numbers.

andy1234
06-03-2007, 03:12 PM
i think this whole thing with the indepence if baiscaly the same if you have the same model wether itll be 2ohm 4 or 8 its have the same effect no matter if you give them all the same power but you got to also look at alot of home audio and PA systems most of them are 8 ohm range and its all on how the speaker is made for. look at how loud a regualr pa speaker can get compared to another driver that takes 4-5 times more power. its all bout design and what works best with the application wether it be home car or else where and the type of power available i think


i know i know didnt make much sence but im lost right now