why is efficiency so critical

[dustybear300ex 10+ year member]

ok so from what i understand...an spl sub will have high efficiency and an sq sub will have lower. you would want a higher qms with an spl sub im guessing because that would indicate having a stiffer suspension and more loss because of it? it seems to me that the efficiency of the sub would be one of the final determining factors inmaking a choice between two of them. i mean if sub x and sub y are nearly identical in parameters except for efficiency wouldnt you go wit the one with a higher rating... it just seems like common sense would tell you to.

i am having trouble grasping some of the car audio concepts postedon this site and have been submitting new threads...nearly 1 a day, so thankyou to those that are giving me answers to my questions that may be somewhat obvious.

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[T3mpest 10+ year member]

It's usually the other way around. A SPL sub usually isnt' as effecient as a daily driving sub or SQ sub. This is because as you throw loads of power on a sub it's effeciency becomes less of an issue, who cares how loud a sub will be on 300watts when your burping with 10,000? Overall you can't really look at any 1 stat to pick a woofer. As a matter of fact, if every other stat was a the same, effeceincy would be the same value as well. However, if you know you dont' have a lot of power to work with a sub with a lower RMS and high effeciency is a good bet.

 

[JimJ 5,000+ posts]

Efficiency for subwoofers is highly overrated, as the enclosure will determine the system's efficiency to a much greater extent.

You can't look at a single T/S spec and make your decision on that, you have to take everything into account including what kind of alignment the driver is going to ultimately be in.

 

[Raven 10+ year member]

Where to start...

OK, I guess I should mention that efficiency is NOT a good deciding factor is picking a woofer. Any number related to the efficiency of a woofer goes out the window once you get it in an enclosure, in your vehicle, and hooked up to more than the 1 watt is was rated at. That's the biggest reason IMO why you shouldn't worry about efficiency. You want for your watt? A bigger box and skill does it, not a few extra dBs in the efficiency rating.

EDIT: Sheesh, 20 minutes trying to word the post right and two people beat me to the post. I should think less and post more, I guess. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[audiolife 5,000+ posts]

spl system is based on design of the box to the power at which it will be used. there have been vehicles that used 14 6x9's to hit almost 170 db. whole point to it was to show that design was the key

 

[Fast1one 10+ year member]

spl system is based on design of the box to the power at which it will be used. there have been vehicles that used 14 6x9's to hit almost 170 db. whole point to it was to show that design was the key

Lol that vid was pretty funny...

 

[audiolife 5,000+ posts]

i was shocked

 

[Remotia 10+ year member]

Efficiency for subwoofers is highly overrated, as the enclosure will determine the system's efficiency to a much greater extent.
You can't look at a single T/S spec and make your decision on that, you have to take everything into account including what kind of alignment the driver is going to ultimately be in.

For the record, sensitivity is VERY VERY VERY important for subwoofers, that is one of the most critical aspects and measurements we look at when we design drivers. If a driver is 1 less dB than another driver, then its 1 less dB unless you put more power into it to match it, no matter WHAT output. There is much more to be said, but for simplicity, you can rest assure that SPL @ 1 watt will tell you just how loud a subwoofer is going to be relative to another subwoofer with similar voice coil dimensions and suspension system (compliance)

Now, T/S does not tell all, we actually use a Klippel analyzer when we test our subwoofers. You can exact insight into each driver and can look at inductance curves, Bl curve and cms curves along with THD at very high power levels as well as power compression.. etc etc... all beyond the scope of my point.. Sensitivity is critical!

Why do you think digital designs gets such good numbers for SPL? Look at their sensitivity, they are off the charts! Why do you thnk the MTX Jackhammer is a dog? It pulls 84dB with one watt and cant make up for it without power compression relative to some of the high sensitivity 18" drivers that our louder than it outright.

And if you what you are looking at, T/S can be very VERY insightful.

 

[Remotia 10+ year member]

spl system is based on design of the box to the power at which it will be used. there have been vehicles that used 14 6x9's to hit almost 170 db. whole point to it was to show that design was the key

Not all true, the design is key, but if you start with a low sensitivity driver, you'll always be lacking relative to a higher sensitivity driver, more dB is more dB, and with SPL you don't have to worry about power compression before you only burp for mili-seconds at a time.

 

[Raven 10+ year member]

Remotia, amateur mistakes in install - as little as he front to back placement of a seat or moving the box a few inches can account for 1 dB. Rest assured, experience and hard work will always counter that loss of 1dB.

 

[VereChronicus 10+ year member]

NUH UH....That's not what JL says on their spec sheets...and JL is ALLAH on Earth.

** Efficiency (1W/1m) is not an accurate indicator of a subwoofer’s output capability and should not be used as a comparison to other subwoofers to determine which one is “louder”.

Stoldeded scraight from dere website. Bow to the almighty (advertising geniuses) JL Audio.

 

[JimJ 5,000+ posts]

For the record, sensitivity is VERY VERY VERY important for subwoofers, that is one of the most critical aspects and measurements we look at when we design drivers. If a driver is 1 less dB than another driver, then its 1 less dB unless you put more power into it to match it, no matter WHAT output. There is much more to be said, but for simplicity, you can rest assure that SPL @ 1 watt will tell you just how loud a subwoofer is going to be relative to another subwoofer with similar voice coil dimensions and suspension system (compliance)
Now, T/S does not tell all, we actually use a Klippel analyzer when we test our subwoofers. You can exact insight into each driver and can look at inductance curves, Bl curve and cms curves along with THD at very high power levels as well as power compression.. etc etc... all beyond the scope of my point.. Sensitivity is critical!

Why do you think digital designs gets such good numbers for SPL? Look at their sensitivity, they are off the charts! Why do you thnk the MTX Jackhammer is a dog? It pulls 84dB with one watt and cant make up for it without power compression relative to some of the high sensitivity 18" drivers that our louder than it outright.

And if you what you are looking at, T/S can be very VERY insightful.

Solid state amplifier power, on average, is pretty cheap. We're not trying to extract every last watt out of a triode output stage, so we don't need the sacrifices mandated by ultra-high sensitivity drivers such as Lowthers and Fostex's. In addition, playing around with the enclosure size is critical for determining the system's overall efficiency in a vehicle. You cannot simply say Sub A will be louder than Sub B in every install because Sub A has a higher efficiency. Well, you could, but you'd be flat-out wrong.

Higher efficiency is not always desired, as well - loss of Mms and an increase in Fs may be fine for a midrange playing 100Hz and above, but for a subwoofer it could lead to mechanical issues...

I'd much rather have a lower sensitivity driver and build the enclosure to maximize output rather than make the dangerous tradeoffs to build a sub that models well on paper but folds cones when put to power.

 

[bigbassman Premium Member]

millisecond burps?

try 2 seconds //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

the termlab sensor has a full 1 second sample cycle... which means you better burp for 2 seconds to assure you don't cut it off in mid sample..

personally... efficiency doesn't factor into the top 5 things I look at when judging a woofer for its SPL capability //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Loyd L.

 

[Remotia 10+ year member]

NUH UH....That's not what JL says on their spec sheets...and JL is ALLAH on Earth.
** Efficiency (1W/1m) is not an accurate indicator of a subwoofer’s output capability and should not be used as a comparison to other subwoofers to determine which one is “louder”.

Stoldeded scraight from dere website. Bow to the almighty (advertising geniuses) JL Audio.

All things being eequal, like i said in my statement, the driver with higher sensitivty will win because it will power compression at higher SPL... Do i need to explain that more?

 

[JimJ 5,000+ posts]

Do i need to explain that more?

Please do.