theorhetical vs. application

[slim j 10+ year member]

I have heard that

a) if you double cone area ---~3 db gain

b) if you port the box ---~3db gain

c) if up double the power ---~3 db gain

I wouldn't think it you did all 3 that you would get a ~9db gain, but maybe. I was wondering which, in general, in real applications is most closely related to its theorhetical gain.

I know this may be install dependant, but I was curious if anyone ever did a test.

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[CBFryman2 5,000+ posts]

I have heard that
a) if you double cone area ---~3 db gain

b) if you port the box ---~3db gain

c) if up double the power ---~3 db gain

I wouldn't think it you did all 3 that you would get a ~9db gain, but maybe. I was wondering which, in general, in real applications is most closely related to its theorhetical gain.

I know this may be install dependant, but I was curious if anyone ever did a test.

Let's first analyze where these come from.

a.) This is Theoretical anecho at best. When you double displacement YES! in fact you do gain 3db...but in a scence that you add another woofer you also halv over all system efficency off of a given power. This, in theory, would mean that you gain 0dB but we know that not to be true. With the same exact power (which is impossible with most amplifiers) you could gain 2-3dB usually. Which is a mild to moderate increase in loudness. Because doubleing woofers means halving impeadance (when wired in parallel) it oculd be 9dB or more...which is doubleing loudness.

b.) Porting the box, in theory anecho will gain an AVERAGE of 3dB over the entire banwith. This is theoredical anecho. Put the box in a cabbin and apply real power to it and realize that in a subwoofer application you are operating with in an octave of the tuning frequincy most of the time and you are looking a a 3-9dB gain over all and as much as a 12dB gain in your peak. Realize I said AS MUCH, and agian these are big generalizations. THey are also anecho. In car it could be the same or it could be even more or even less.

c.) Double power does, in theory, double displacement and there for gain 3dB. However...realize that doubleing power could raise the voltage enough to push past the inductance...the more voltage you apply the lower the effects of inductance have on the impeadance... You could also run into power compression problems when you double power. 1w to 2w this will hold true. 1000w to 2000w you may gain 3db, 5dB, 1dB, 0.5dB. Entirely application dependant.

Going from a single 12" in a sealed enclosure to two 12's in a ported enclosure with twice the power could yeild 6dB or it could yeild a whopping 20dB+ which is 4 times as loud.

All of thoes are generalizations refering to an anecho environment. Real woofers with real power in a real vehicle is another story. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[Flipx99 5,000+ posts]

What is anecho?

 

[.::DuD3::. 10+ year member]

What is anecho?

x2, not on dictionary.com lol

Let's first analyze where these come from.
a.) This is Theoretical anecho at best. When you double displacement YES! in fact you do gain 3db...but in a scence that you add another woofer you also halv over all system efficency off of a given power. This, in theory, would mean that you gain 0dB but we know that not to be true. With the same exact power (which is impossible with most amplifiers) you could gain 2-3dB usually. Which is a mild to moderate increase in loudness. Because doubleing woofers means halving impeadance (when wired in parallel) it oculd be 9dB or more...which is doubleing loudness.

b.) Porting the box, in theory anecho will gain an AVERAGE of 3dB over the entire banwith. This is theoredical anecho. Put the box in a cabbin and apply real power to it and realize that in a subwoofer application you are operating with in an octave of the tuning frequincy most of the time and you are looking a a 3-9dB gain over all and as much as a 12dB gain in your peak. Realize I said AS MUCH, and agian these are big generalizations. THey are also anecho. In car it could be the same or it could be even more or even less.

c.) Double power does, in theory, double displacement and there for gain 3dB. However...realize that doubleing power could raise the voltage enough to push past the inductance...the more voltage you apply the lower the effects of inductance have on the impeadance... You could also run into power compression problems when you double power. 1w to 2w this will hold true. 1000w to 2000w you may gain 3db, 5dB, 1dB, 0.5dB. Entirely application dependant.

Going from a single 12" in a sealed enclosure to two 12's in a ported enclosure with twice the power could yeild 6dB or it could yeild a whopping 20dB+ which is 4 times as loud.

All of thoes are generalizations refering to an anecho environment. Real woofers with real power in a real vehicle is another story. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

so you're saying if you add another woofer and give it the same amount of power that the other woofer was handling, but divide it among evenly between both woofers, you'll still see a 2-3dB increase? explain //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[Relax 10+ year member]

x2, not on dictionary.com lol
so you're saying if you add another woofer and give it the same amount of power that the other woofer was handling, but divide it among evenly between both woofers, you'll still see a 2-3dB increase? explain //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

anecho- echoLess chamber- means only the sub's output is measured, no cancelation or addition of waves.

To gain 3db when double surface area, the same amount of power needs to be given to each woofer. Meaning 1 12 sub on 200w is in theory as loud as 2 12 subs on 100w. You give them 200w each and you get +3db.

The problem comes when people say add a subwoofer. Depending on how you wire subs up- you may not need to add power at all to see this increase. Example would be a mono amp that does 200w at 4 ohms, 400w at 2 ohms. Say we hook the single 12 above up (its a 4 ohm sub) it would get 200w. If we parallel the second sub for 2 ohms- the amp will put out 400w. Hence we get the same 200w to each woofer and 2 x the cone area. But if this amp only did 300w at 2 ohms- we would see less then 3 db increase.

Of course none of this really matters, as doing any of this in a car would probably result in a greater increase, somewhere around 6dB I would guess.

 

[CBFryman2 5,000+ posts]

Relax summed it up pretty well. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[reneeb7363 10+ year member]

actually anechoic (anti-echo)

wiki def here: http://en.wikipedia.org/wiki/Anechoic_chamber

"An anechoic chamber is a room in which there are no echoes. This description was originally used in the context of acoustic (sound) echoes caused by reflections from the internal surfaces of the room ..."

 

[CBFryman2 5,000+ posts]

actually anechoic (anti-echo)
def here: http://en.wikipedia.org/wiki/Anechoic_chamber

"

anecho- echoLess chamber

kthxbi

 

[reneeb7363 10+ year member]

anecho is NOT a word

Edit: Thank you for the great information tho!

 

[Relax 10+ year member]

anecho is not a word- we were just using it because its kind of slang for anechoic (plus I couldn't remember the spelling.)

 

[nauc 10+ year member]

and dont forget that doubling the power might not get you anything, depends on how much the speaker/sub is already moving

 

[CBFryman2 5,000+ posts]

anecho is NOT a word

Edit: Thank you for the great information tho!

aint aint a word and I aint gonna use it. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif