posted
The easiest way to figure it out is to figure out the Vd of your driver (surface area * stroke). Assume your driver will displace that much of the box on the back stroke, and starting at ~14 psi you can figure out how high box pressure is when the woofer is in stroke.
(p1v1 = p2v2 where p1 = atmospheric 14psi, v1 = box inner volume, v2 = box vol. - Vd, so p2 = 14psi*Vb/(Vb-Vd) or thereabouts.
The pressure inside a ported box (or any box) is a fairly complicated matter as it isn't consistent all the way across the box, at a given moment in a ported box you can have a larger pressure front than in a sealed box, however a ported box won't sustain that pressure for long because that pressure front is what is responsible for the back wave coming out the port.
ShadowStar
-------------------- You can't build a reputation for what you're GOING to do.. But you can build one for TALKING about it!
It's all about knowledge, love and respect. Posts: 2578 | From: Somewhere In the Northeast | Registered: May 1999
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But you should indicate that this formula take only account of absolute pressure (1 atm = 14.7psi). + ((relative pressure created by the cone...)) if you want to know only the pressure created by the cone see below..
-------------------- Street A "not legal but not outlaw!" Score in my integra: -152.34 dB 51Hz TL sensor -157,1dB 51Hz AC mic
2005-2006 Street A Champion in Quebec province!
CRAZY TESTs: ||||||THE ONLY 6.5" TO SCORE 168.9dB(TL)OUTLAW IN THE WORLD with 6 Watts.|||||| -Crazy 5.25 Bose sub 1.1cu box: 138.0dB TL mic 55Hz with ONLY 100W ! ---------------------------------- www.teamxmax.com Posts: 643 | From: Quebec city | Registered: Mar 2000
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quote:Originally posted by kickercar: goto pepboys and find a boost gauge and hook it up to the box lol
Just remind that actually, THE Termlab pressure sensor use and integrate the exact same sensor then the vaccum or pressure gauge on the intake of the engine of a car... that's motorola that make them... I already posted something about that...
-------------------- Street A "not legal but not outlaw!" Score in my integra: -152.34 dB 51Hz TL sensor -157,1dB 51Hz AC mic
2005-2006 Street A Champion in Quebec province!
CRAZY TESTs: ||||||THE ONLY 6.5" TO SCORE 168.9dB(TL)OUTLAW IN THE WORLD with 6 Watts.|||||| -Crazy 5.25 Bose sub 1.1cu box: 138.0dB TL mic 55Hz with ONLY 100W ! ---------------------------------- www.teamxmax.com Posts: 643 | From: Quebec city | Registered: Mar 2000
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posted
If you want absolutly a number.. i would say around 0.1 to 4 PSI inside a box if the sensor is placed at the opposite corner of the sub.
0.1 psi = 154dB that is easy to reach with most sommon comercial sub..
5 psi = 183dB that is near the max scored in outlaw... and it mean that you displace 1/6 of the internal volume of air inside the box using the woofer !
Doc
-------------------- Street A "not legal but not outlaw!" Score in my integra: -152.34 dB 51Hz TL sensor -157,1dB 51Hz AC mic
2005-2006 Street A Champion in Quebec province!
CRAZY TESTs: ||||||THE ONLY 6.5" TO SCORE 168.9dB(TL)OUTLAW IN THE WORLD with 6 Watts.|||||| -Crazy 5.25 Bose sub 1.1cu box: 138.0dB TL mic 55Hz with ONLY 100W ! ---------------------------------- www.teamxmax.com Posts: 643 | From: Quebec city | Registered: Mar 2000
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quote:Originally posted by Doctorbass: I agree with ShadowStar.
But you should indicate that this formula take only account of absolute pressure (1 atm = 14.7psi). + ((relative pressure created by the cone...)) if you want to know only the pressure created by the cone see below..
Just remain that 20 dB diference is equal to 10 time the force applied .
10db = 10times the energy applied, and typically twice the airpressure
20dB = 100times the power factor
-------------------- World Record-Loudest SPL in my driveway Team Powermaster/XS-Power Hifonics Amps, Kicker subs-The way it should be....all were Stolen from me...boo hoo Zensky....World Domination at It's Finest www.zensky.com Posts: 3714 | From: Columbus, OH - formerly FL | Registered: Oct 2003
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quote:Originally posted by Doctorbass: I agree with ShadowStar.
But you should indicate that this formula take only account of absolute pressure (1 atm = 14.7psi). + ((relative pressure created by the cone...)) if you want to know only the pressure created by the cone see below..
Just remain that 20 dB diference is equal to 10 time the force applied .
10db = 10times the energy applied, and typically twice the airpressure
20dB = 100times the power factor
I was giving an example about PSI..not energy or power factor
1 Pascal = 1 newton per square meter and it is also equal to 94dB of relative sound pressure.
Remember the 0dB we use is in reality 20uPa of pressure.. apparently, it'is due to an error they did when they decided the 0dB level. it should be 0Pa or 0upa or whatever zero. The human hearing limit they measured was'nt totally "no noise" after that, with their scale, some people was able to hear a sound of 0dB.... and some was able to hear -10 dB.. their scale has an offset..
an article about microphone measurement explain: "Signal to noise ratio, S/N The signal to noise ratio, or S/N, expresses the relation between a reference sound pressure level and the A-weighted equiva- lent noise level (self-noise). The reference sound pressure level is 94 dB re. 20 µPa. Hence the signal to noise ratio is 94 dB minus the equivalent noise level."
-------------------- Street A "not legal but not outlaw!" Score in my integra: -152.34 dB 51Hz TL sensor -157,1dB 51Hz AC mic
2005-2006 Street A Champion in Quebec province!
CRAZY TESTs: ||||||THE ONLY 6.5" TO SCORE 168.9dB(TL)OUTLAW IN THE WORLD with 6 Watts.|||||| -Crazy 5.25 Bose sub 1.1cu box: 138.0dB TL mic 55Hz with ONLY 100W ! ---------------------------------- www.teamxmax.com Posts: 643 | From: Quebec city | Registered: Mar 2000
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quote:Originally posted by Doctorbass: If you want absolutly a number.. i would say around 0.1 to 4 PSI inside a box if the sensor is placed at the opposite corner of the sub.
0.1 psi = 154dB that is easy to reach with most sommon comercial sub..
5 psi = 183dB that is near the max scored in outlaw... and it mean that you displace 1/6 of the internal volume of air inside the box using the woofer !
Doc
i thought the technology in the TL was based off of the sensor Chrysler uses for windtunnel tests.
-------------------- World Record-Loudest SPL in my driveway Team Powermaster/XS-Power Hifonics Amps, Kicker subs-The way it should be....all were Stolen from me...boo hoo Zensky....World Domination at It's Finest www.zensky.com Posts: 3714 | From: Columbus, OH - formerly FL | Registered: Oct 2003
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-------------------- Street A "not legal but not outlaw!" Score in my integra: -152.34 dB 51Hz TL sensor -157,1dB 51Hz AC mic
2005-2006 Street A Champion in Quebec province!
CRAZY TESTs: ||||||THE ONLY 6.5" TO SCORE 168.9dB(TL)OUTLAW IN THE WORLD with 6 Watts.|||||| -Crazy 5.25 Bose sub 1.1cu box: 138.0dB TL mic 55Hz with ONLY 100W ! ---------------------------------- www.teamxmax.com Posts: 643 | From: Quebec city | Registered: Mar 2000
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posted
i've had people refer to me as doctor bass, assuming that's where it came from...
i say, nope. i don't need the confusion.
D-Bass and Doctorbass.....spooky.
-------------------- World Record-Loudest SPL in my driveway Team Powermaster/XS-Power Hifonics Amps, Kicker subs-The way it should be....all were Stolen from me...boo hoo Zensky....World Domination at It's Finest www.zensky.com Posts: 3714 | From: Columbus, OH - formerly FL | Registered: Oct 2003
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