Some people were talking about aiming the sound pressure at the mic to increase the spl measurement. Since high frequency is more directional, why not use a big monster tweeter? I know nothing about these spl contests and their rules, but if I were going to try something I would build a narrow horn facing the mic. Get multiple titanium diaphram PA style tweeter motors (type used in outdoor concerts) and just blast away.
posted
In dB drag you must play under 80 Hz, so high frequencys wouldn't work, you'd have to go outlaw if you want to try that.
-------------------- My system right now: A Sony HU and Focal Access 5.25" front system Posts: 553 | From: Vasa, Finland | Registered: Nov 1999
| IP: Logged |
posted
Wow! I didn't remember that I posted in this thread back in 2002. There's some good reading material here.
-------------------- My system right now: A Sony HU and Focal Access 5.25" front system Posts: 553 | From: Vasa, Finland | Registered: Nov 1999
| IP: Logged |
posted
Me too!.. and i see here that some idea about the 180dB barrier have changed!.. it's now about scealed enclosure BUT BANDPASS style enclosure like Scott Owen truck
-------------------- 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: 645 | From: Quebec city | Registered: Mar 2000
| IP: Logged |
posted
im building something similar to the edge audio truck in an explorer. i say similar but no im not copying in any way. its actually quite different, but on paper it seems similar. its only using a partially enclosed half wall, like a sonotube/bandpass half wall. ill let you know how that works.
-------------------- Kenneth- TEAM DAILY Louisville, KY Posts: 1325 | From: Floyds Knobs, IN | Registered: Mar 2005
| IP: Logged |
posted
wow whomever said that car audio has no educational values and we are a bunch of dumb bassheads needs to read this thread
Posts: 37 | From: warner robins ga. | Registered: Oct 2006
| IP: Logged |
posted
Theres alot of good threads around here that involve critical observation and mathmatics. It's just a matter of moving past the typical walmart boombox mentality.
-------------------- Yes this is my sig, no there is nothing for you to see. Quit looking at me, nothing is going to happen. Stop staring at me, cut it out, leave me alone.... Posts: 3084 | From: AZ | Registered: May 2003
| IP: Logged |
I'm chiming in late but I have to say a few things.
1. I don't think sound pressure = air pressure 2. Given that I believe you use the air pressure to control certain aspects of you woofer loading. 3. so as to get the woofers to make the most violent sound pressure possible to equal Max SPL. 4. a focused sound wave would be more effective then one which is wide or multiple, because a focused wave will not cause sound cancellation like those other designs. 5. I learned that the air in the box of a ported enclosure was the spring and that the air in the port was the diaphragm and acted just like a passive radiator. And that air would move forward and backwards like a diaphragm, so that there wasn't any actual air really escaping from the box. But the air just in front of the port could be excited to move like the air coming off the woofer itself. 6. Finding the resonant Frequency and working with it to enhance your spl is better then working against it. (it's better to surf with the waves toward the shore then to fight paddling back out).
These are the principles I use for my spl installations
quote:Originally posted by Whip11: 1. I don't think sound pressure = air pressure
The two are not equal but there is a definite relationship between them. Any medium, such as air, at equilibrium has a rest pressure. If something happens within the medium (say a speaker cone moves forward), the air pressure deviates some from the rest pressure. That deviation is sound pressure.
Posts: 3961 | From: State College, PA | Registered: Sep 2000
| IP: Logged |
posted
You are right when you call air the medium, with out air molecules to vibrate we have no sound. I am sure that air pressure is a by product of producing sound like heat is a by product of certain energy s.
You should also remember that that woofer that goes out also goes back an equal amount thus canceling the the out force. there is some air disturbance but not near as much as the sound wave that is produced. If air pressure was a good indicator of sound pressure we would install a valve in our cars to prevent the cone movement backwards from registering like reed valves in a compressor.
posted
All sound is is fluctuations in air pressure! That is what sound pressure is; a sound wave is just that disturbance propogating. While it is true that the net volume displacement over one cycle is zero, the "force" does not "cancel"- the cone motion causes a pressure fluctuation in front of it and that, because of the springiness of air, propogates outward.
Posts: 3961 | From: State College, PA | Registered: Sep 2000
| IP: Logged |
posted
Air pressure is relatively static and is decided by the amount of air molecules, the temperature and the volume of space in which it resides.
For most intents and purposes, the air pressure around us at sea level is a little over 14PSI
Sound is just that : Sound. In order to be considered a sound, there must be a cyclic variation of pressure. Typically it is cyclic around an equilibrium (which happens to be the air pressure around us.) The magnitude of the cycles (judged by their amplitude, in pressure units) gives the SPL. This is all straight from a physics book.
For another point to consider - Is it more efficient to produce pressure variations in a high pressure environment (for example, a 20psi relative air pressure, an unlikely scenario) or in a low pressure environment (for example, a 10psi relative air pressure, also an unlikely scenario?)
For example, which allows more of the work done by the motor to be transferred into sound energy and the least energy lost to other considerations? (More complex issues such as phase addition are excluded from the query.
-------------------- 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: 2579 | From: Somewhere In the Northeast | Registered: May 1999
| IP: Logged |
![[Razz]](tongue.gif)
![[Wink]](wink.gif)
![[Cool]](cool.gif)
Printer-friendly view of this topic