sensitivity?

[mr_imperial 10+ year member]

what exactly is it and how does it affect a subs performance??

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[Rich B 5,000+ posts]

If you call it bad names, your sub gets upset.//content.invisioncic.com/y282845/emoticons/crying.gif.ec0ebefe590df0251476573bc49e46d8.gif

//content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

or

Its how loud it gets based on 1w @ 1 meter.

The louder, the more sensitive.

SPL subs tend to require more power than SQ subs as an example due to the large magnets and stiff surrounds needed to handle large amounts of power.

 

[Raven 10+ year member]

It's a bunk term.

It means if you put a woofer on an infinite baffle, put a mic 1 meter directly in front of the cone, and apply exactly 1 watt at 1khz, you will produce XX dB of output.

The problems with sensitivity are as follows:

1) There is a lack of set standards. MFG's can easily cheat the system to make a driver look like it's more efficient than it really is. As an example, different SPL meters can vary by up to 10dB. Pick the right meter, and your 88dB driver becomes a 93dB driver.

2) There is no account for in-vehicle cabin gain

3) There is no account for a not-infinite-baffle enclosure

4) You are sending the speaker 1 watt.

 

[mr_imperial 10+ year member]

thanks guys for the help and is the frequency how low it will go

 

[helotaxi 5,000+ posts]

You are also measuring a SUB at 1 kHz. The term is totally worthless with most subs.

 

[squeak9798 5,000+ posts]

It's a bunk term.
It means if you put a woofer on an infinite baffle, put a mic 1 meter directly in front of the cone, and apply exactly 1 watt at 1khz, you will produce XX dB of output.

The problems with sensitivity are as follows:

1) There is a lack of set standards. MFG's can easily cheat the system to make a driver look like it's more efficient than it really is. As an example, different SPL meters can vary by up to 10dB. Pick the right meter, and your 88dB driver becomes a 93dB driver.

Technically, if you have the sub's full specs, it's not hard to calculate the TRUE sensitivity of the subwoofer regardless of the manufacturer's "stated" figure using the formula;

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

Where Vas is in Litres

But many manufacturer's do play the trick of using unorthodox measurement methods to rate their subs sensitivity. Some use more than 1w (3db increase for every doubling of power). Some measure at a distance other than 1m (such as .5m, which would yield an increase of 3db). Some measure in something other than "free space", such as Infinity who measured the sensitivity in-car. So you're not always comparing apples to apples.

That said.....Sensitivity is pretty meaningless for the most part with regard to subs. About the only thing I use it for is a very brief reference to the subwoofers potential box size and low frequency output based on Hoffman's Law. Small box, sensitivity, low frequency extension. You can only have two of the three. So if a sub has a high [true] sensitivity, it's a guarantee you are going to have to give up one of the two remaining. Likewise, you can see why high sensitivity is not inherently desireable.

Beyond that...it's of little use.

 

[iceteebone 5,000+ posts]

Technically, if you have the sub's full specs, it's not hard to calculate the TRUE sensitivity of the subwoofer regardless of the manufacturer's "stated" figure using the formula;
SPL=112+10*LOG(9.64*10^(-10)*Fs^3*Vas/Qes)

Where Vas is in Litres

That said.....Sensitivity is pretty meaningless for the most part with regard to subs. About the only thing I use it for is a very brief reference to the subwoofers potential box size and low frequency output based on Hoffman's Law. Small box, sensitivity, low frequency extension. You can only have two of the three. So if a sub has a high sensitivity, it's a guarantee you are going to have to give up one of the two remaining.

Beyond that...it's of little use.

wow i never seen logairthims used in real life applications. //content.invisioncic.com/y282845/emoticons/eek.gif.771b7a90cf45cabdc554ff1121c21c4a.gif

 

[thch 10+ year member]

pretty much anything engineering uses logrithms.

this case its only used to convert from the logrithmic scale (dB) to the linear scale.

its used a bit in computer science, and in many physical applications.

 

[Raven 10+ year member]

Technically, if you have the sub's full specs, it's not hard to calculate the TRUE sensitivity of the subwoofer regardless of the manufacturer's "stated" figure using the formula;
SPL=112+10*LOG(9.64*10^(-10)*Fs^3*Vas/Qes)

Where Vas is in Litres

I see someone has been into the Adire Tech Papers. =) I totally forgot all about that until you mentioned it.

 

[squeak9798 5,000+ posts]

I see someone has been into the Adire Tech Papers. =) I totally forgot all about that until you mentioned it.

I actually read about it in the LSDC.

But, no matter, Adire has it in their tech pages aswell.