Spl (1w/1m)

 

Silver Member
Username: Rob_brown

Post Number: 162
Registered: Jul-04
What does this mean? for instance 89.3 or 92 spl (1w/1m)? thanks
 

Silver Member
Username: Cory

Canada

Post Number: 140
Registered: Jan-05
it means if i were to be standing 1 meter away from the speaker that the spl will be at 89.3 or 92 as you stated
 

Silver Member
Username: Cory

Canada

Post Number: 141
Registered: Jan-05
at my ears

so if i were to have a speaker with 92db at 1 mete, and a 130watt amplifier you could hit 113DB


watts/db
1=92
2=95
4=98
8=102
16=105
32=108
64=111
128=114

 

Gold Member
Username: Invain

Michigan United States

Post Number: 1661
Registered: Aug-04
NO. You cannot just take the effeciency of the sub and plug it into a formula.
 

Silver Member
Username: Cory

Canada

Post Number: 144
Registered: Jan-05
that is true because it does not take into consideration of a the box and the enviroment but will give you an idea
 

Gold Member
Username: Invain

Michigan United States

Post Number: 1662
Registered: Aug-04
Roughly. Spl does depend on other things as well. You also have to take into consideration the speaker design.

The difference in the xmax is due to the difference in overall length of the voice coil. Xmax=voice coil length minus the gap height. The difference in efficiency is due to a different number of windings in the gap. The current passing through the coil generates a magnetic field which is distributed along its length. On a shorter voice coil, more of the generated field is in the magnetic gap producing a slightly stronger motor but with a shorter stroke. You can make a speaker really efficient by designing the voice coil to fit entirely in the magnetic gap. This would likely yield a sensitivity of 104 or so. This speaker may work very well if powered by a low powered amplifier because of the high efficiency but would not be able to produce high SPL at low frequencies because it would have a very small xmax.

You also have to consider the frequency played, as well as the xmax of the speaker. Efficiency alone should never be used to find the db's a sub will hit.
 

Silver Member
Username: Cory

Canada

Post Number: 145
Registered: Jan-05
ok, I see what you mean by high sencitivity put with high x-max. So in other words when the cone is at high excursion it leaves the magnet gap witch reduces the sencitivity b/c its not as close to were it once was in the normal position in the magnet gap.

please correct me if im wrong. I did not know that. I geuss it is true you do learn somthing every day
 

Gold Member
Username: Invain

Michigan United States

Post Number: 1664
Registered: Aug-04
Not really, it just doesn't have as much xmax - excursion. In order to produce lower nots a sub needs to be able to go through more excursion.

"So in other words when the cone is at high excursion it leaves the magnet gap"

I don't believe that's possible. If the voice coil left the magnet gap the sub would no longer have any control over the cone.
 

Silver Member
Username: Cory

Canada

Post Number: 148
Registered: Jan-05
ok,true ture thanks for the info on the matter. never looked at it like that before.
 

Gold Member
Username: Invain

Michigan United States

Post Number: 1668
Registered: Aug-04
No problem. I hope I didn't come off as rude, lol. When I read my responses a second time it sorta sounded that way. I just wanted to correct you.
 

Silver Member
Username: Cory

Canada

Post Number: 150
Registered: Jan-05
no offence taken, we all have to be corrected some time
 

Gold Member
Username: Invain

Michigan United States

Post Number: 1671
Registered: Aug-04
Good, lol.
 

Gold Member
Username: Jonathan_f

GA USA

Post Number: 3468
Registered: May-04
Not a good basis to go by really. Once you put a couple hundred watts on a subwoofer, results change. The sensitivity of a subwoofer (or speaker for that matter) does not relate to it's efficiency, which would be the power in compared to the power out, and it won't dictate how loud a subwoofer is capable of getting. Many manufacturers rate sensitivity differently, you have to consider the type of enclosure they used, whether free air, sealed, etc. and also the location they put it in when they measured it. An example is the Infinity Kappa Perfect subwoofer, the 96db figure may look good, but they measured that with 2.83V instead of the typical 1W/1M sensitivity, and also put that subwoofer in a car for the measurement and not anechoic, which boosts the sensitivity by a huge amount. Independant tests have measured that sub in the 80s with normal methods of testing at 1W/1M. You also have to consider the frequency they measured at and other factors. High sensitivity is usually accomplished with lightweight materials, such as a light cone, foam surrounds, and looser suspension, also motor strength plays a big part of it. Lightweight can be bad or good depending on what you're looking at, too light can result in a lack of damping of the driver, degrading SQ. Subwoofers are capable of moving out of the magnetic gap with enough power, but of course it usually isn't recommended. If you have the suspension to handle it, you can stay somewhat linear doing so, but you do lose motor strength and a lot of control, like Joe stated. This is typically done in sealed boxes with high power, especially at the resonant frequency of the system.
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