Why do I never see high efficiency subwoofers used for SPL purposes?

[lithium 358]

 

According to most sensitivity ratings, it would take thousands of watts to break 120dB... This should tell you that we need to disregard sensitivity ratings for subwoofers. 

You are forgetting acoustics my friend.

 

 

cabin gain  

[Lee Carter 150]

It is 90% install, 10% beer.

 

Post of the day!

[Tenacious 32]

 

According to most sensitivity ratings, it would take thousands of watts to break 120dB... This should tell you that we need to disregard sensitivity ratings for subwoofers. 

You are forgetting acoustics my friend.

 

The post wasn't meant to be entirely technical. But touche.

 

1w SPL means nothing, though, since all subs react differently to varying amounts of power.

[stevemead08 752]

I won't be using a ton of power in my truck to start off. I will however be trying out different combos and testing more for efficiency.

[///M5 2,833]

According to most sensitivity ratings, it would take thousands of watts to break 120dB... This should tell you that we need to disregard sensitivity ratings for subwoofers.

You are forgetting acoustics my friend.

The post wasn't meant to be entirely technical. But touche.

 

1w SPL means nothing, though, since all subs react differently to varying amounts of power.

Umm, wrong. It means exactly what it is, efficiency is related to output per watt. Doesn't mean manufacturers measure it appropriately for the task at hand.

Todd, the answer is really rather simple. Box size & cheap power. PA drivers need a ton of space and while they run with less power, power is cheap so why waste all the space.

I have an awesome car audio errr pro audio driver in my basement. The first "beast" subs were pro audio subs that were slightly massaged for car audio applications, but this is when a 1000w amp was rare so you just dealt with the needed box size since it was the best choice.

[95Honda 486]

As all have pretty much said.  Most drivers intended for pro-sound require large enclosures to make their efficiency shine.

 

Also, this isn't a new idea.  There have been a few pro-sound drivers on the block for decades,, that would fit this application.  I have used both of them.  In the early 90's I did a few pro-audio installs with the McCauley 6174 18" driver.  I was highly efficient, had a low Fs and almost 3/4" of one way linear excursion.  I also have used the Aura 1808 (and the newer NRT-18) several times over the last few decades.  It also was very efficient, had a low Fs and plenty of excursion...  Both very low distortion high output drivers...  The drawbacks?  They were $1000 each, even back in the day, and they needed relatively large enclosures...  BUT, if you were in some type of class that limited you to say a single driver of any size and low power, say 500 watts, and you had no enclosure limitations, then these two drivers would be every car audio driver, hands down...  But that really doesn't really fit into any classes that I am aware of...

 

Here are the boxes I made for (4) of the Aura 18's almost 10 years ago...  They are like 20ft3 each, lol...  Also, that is $4k for (4) subs...

 

 

[95Honda 486]

Check out the specs on these drivers, lol...

 

http://www.ari-web.com/aurasound/pdf/nrt18-8.pdf

 

 

[j-roadtatts 1,129]

Awesome pics 95! I love me some Aura's! Have the NS12's for mids in my Honda. 

 

I have an old MTX sub that is rated at like 96db. Got stupid loud on 150 watts. I personally would consider the Dcon a pretty efficient driver too. BTW

[gprestonmoto 89]

As all have pretty much said.  Most drivers intended for pro-sound require large enclosures to make their efficiency shine.

 

Also, this isn't a new idea.  There have been a few pro-sound drivers on the block for decades,, that would fit this application.  I have used both of them.  In the early 90's I did a few pro-audio installs with the McCauley 6174 18" driver.  I was highly efficient, had a low Fs and almost 3/4" of one way linear excursion.  I also have used the Aura 1808 (and the newer NRT-18) several times over the last few decades.  It also was very efficient, had a low Fs and plenty of excursion...  Both very low distortion high output drivers...  The drawbacks?  They were $1000 each, even back in the day, and they needed relatively large enclosures...  BUT, if you were in some type of class that limited you to say a single driver of any size and low power, say 500 watts, and you had no enclosure limitations, then these two drivers would be every car audio driver, hands down...  But that really doesn't really fit into any classes that I am aware of...

 

Here are the boxes I made for (4) of the Aura 18's almost 10 years ago...  They are like 20ft3 each, lol...  Also, that is $4k for (4) subs...

 

 

You retire out as a Tech?

[95Honda 486]

Retired?  No.  I have been in for 16.  That was a while ago...

[gprestonmoto 89]

Awesome. Didn't realize we had a few military people here. What's your AFSC?

[95Honda 486]

3D1, came from Radio Maintenance...

[Tenacious 32]

 

 

 

According to most sensitivity ratings, it would take thousands of watts to break 120dB... This should tell you that we need to disregard sensitivity ratings for subwoofers.

You are forgetting acoustics my friend.

 

The post wasn't meant to be entirely technical. But touche.

 

1w SPL means nothing, though, since all subs react differently to varying amounts of power.

 

Umm, wrong. It means exactly what it is, efficiency is related to output per watt. Doesn't mean manufacturers measure it appropriately for the task at hand.

Todd, the answer is really rather simple. Box size & cheap power. PA drivers need a ton of space and while they run with less power, power is cheap so why waste all the space.

I have an awesome car audio errr pro audio driver in my basement. The first "beast" subs were pro audio subs that were slightly massaged for car audio applications, but this is when a 1000w amp was rare so you just dealt with the needed box size since it was the best choice.

 

 

Actually, different loudspeakers react differently to different power levels. I'm sure you've heard of power compression.

 

The efficiency rating is nothing more than the output at 1w/1m. It does not always tell how the loudspeaker will perform with more power.

Edited February 14, 2014 by Tenacious

[///M5 2,833]

According to most sensitivity ratings, it would take thousands of watts to break 120dB... This should tell you that we need to disregard sensitivity ratings for subwoofers.

You are forgetting acoustics my friend.

The post wasn't meant to be entirely technical. But touche.

 

1w SPL means nothing, though, since all subs react differently to varying amounts of power.

Umm, wrong. It means exactly what it is, efficiency is related to output per watt. Doesn't mean manufacturers measure it appropriately for the task at hand.

Todd, the answer is really rather simple. Box size & cheap power. PA drivers need a ton of space and while they run with less power, power is cheap so why waste all the space.

I have an awesome car audio errr pro audio driver in my basement. The first "beast" subs were pro audio subs that were slightly massaged for car audio applications, but this is when a 1000w amp was rare so you just dealt with the needed box size since it was the best choice.

 

Actually, different loudspeakers react differently to different power levels. I'm sure you've heard of power compression.

 

The efficiency rating is nothing more than the output at 1w/1m. It does not always tell how the loudspeaker will perform with more power.

Nice way to try to spin that lol. Ignore it all you like. I am very aware of power compression.

[gprestonmoto 89]

3D1, came from Radio Maintenance...

Awesome. I was 3P051

[Tenacious 32]

 

 

 

 

The post wasn't meant to be entirely technical. But touche.

 

1w SPL means nothing, though, since all subs react differently to varying amounts of power.

 

Umm, wrong. It means exactly what it is, efficiency is related to output per watt. Doesn't mean manufacturers measure it appropriately for the task at hand.

 

 

Actually, different loudspeakers react differently to different power levels. I'm sure you've heard of power compression.

 

The efficiency rating is nothing more than the output at 1w/1m. It does not always tell how the loudspeaker will perform with more power.

 

Nice way to try to spin that lol. Ignore it all you like. I am very aware of power compression.

 

 

How am I spinning things around when that is what I said in my original post, when you decided to call me wrong?

[95Honda 486]

 

3D1, came from Radio Maintenance...

Awesome. I was 3P051

 

Cool.

[95Honda 486]

All drivers have power compression.  That doesn't neglect the efficiency rating. 

[Tenacious 32]

All drivers have power compression.  That doesn't neglect the efficiency rating. 

 

Different drivers have different degrees of power compression, which can very much make the drivers stray from their efficiency ratings at various power levels. Also, there isn't a well-followed standard behind most manufacturer's efficiency ratings, as was stated earlier in the thread.

[lithium 358]

 

All drivers have power compression.  That doesn't neglect the efficiency rating. 

 

Different drivers have different degrees of power compression, which can very much make the drivers stray from their efficiency ratings at various power levels. Also, there isn't a well-followed standard behind most manufacturer's efficiency ratings, as was stated earlier in the thread.

 

 

my guess is that you can minimize that difference if you compare subs of similar power ratings and/or restrict the applied power to something reasonable. 

[Tenacious 32]

 

 

All drivers have power compression.  That doesn't neglect the efficiency rating. 

 

Different drivers have different degrees of power compression, which can very much make the drivers stray from their efficiency ratings at various power levels. Also, there isn't a well-followed standard behind most manufacturer's efficiency ratings, as was stated earlier in the thread.

 

 

my guess is that you can minimize that difference if you compare subs of similar power ratings and/or restrict the applied power to something reasonable. 

 

 

Thermal compression varies with temperature, which is dependant on quite a few factors. Flux compression varies from motor to motor. If you're significantly underpowering both subs, the difference would "probably" be minimal. But, who does that in the car audio world?

[lithium 358]

how much loss is power compression responsible for? is it in the neighborhood of 2-3 db for one woofer or 3-4 db for another? thats not significant if those two woofers have a large difference in efficiency. 

[Tenacious 32]

how much loss is power compression responsible for? is it in the neighborhood of 2-3 db for one woofer or 3-4 db for another? thats not significant if those two woofers have a large difference in efficiency. 

 

Power compression ranged from ~1 to 7dB in a test done by JBL.

Edited February 14, 2014 by Tenacious

[Impious 1,476]

Also, there isn't a well-followed standard behind most manufacturer's efficiency ratings, as was stated earlier in the thread.

Actually sensitivity and efficiency are well defined and easily calculated with TS parameters independent of manufacturer sensitivity ratings. A manufacturer can try to fudge their sensitivity spec, but as long as you have the TS parameters it is very easy to accurately calculate:

Sensitivity (SPL) = 112 + 10*Log(9.64 * 10^(-10) * Fs^3 * Vas / Qes)

*Vas in liters

[Tenacious 32]

 

Also, there isn't a well-followed standard behind most manufacturer's efficiency ratings, as was stated earlier in the thread.

Actually sensitivity and efficiency are well defined and easily calculated with TS parameters independent of manufacturer sensitivity ratings. A manufacturer can try to fudge their sensitivity spec, but as long as you have the TS parameters it is very easy to accurately calculate:

Sensitivity (SPL) = 112 + 10*Log(9.64 * 10^(-10) * Fs^3 * Vas / Qes)

*Vas in liters

 

 

That's assuming the TS parameters are accurate. It's a sad but true fact that a bunch of the popular mass produced Chinese subs can stray pretty far from their published specs... Which is why I tend to avoid said brands.