
Home  Forums  Rules  Articles  diyAudio Store  Gallery  Wiki  Blogs  Register  Donations  FAQ  Calendar  Search  Today's Posts  Mark Forums Read  Search 

Please consider donating to help us continue to serve you.
Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving 

Thread Tools  Search this Thread 
3rd July 2006, 05:22 AM  #1 
diyAudio Member
Join Date: Jul 2006

Calculate SPL
Ok i am a bit slow, is there some calculation given an amount of watts and sensitivty that tells you a theoretical max spl? For example I have SoundStream Tarantual series T415 with a 91db at 1 watt at 1 meter, and will be pushing those with a 2000 watt rm Picasso PCA200D amp also from soundstream. Without sitting there figuring out exponents (2, 4, 8, 16, 32, 64, 128,256,512,1024,2048) i know this because of computer programming lol. By my faulty calculations i would only hit around 124db. I think that is right, 11 doubles in power, 3db gain for a total gain of 33db added to a sensitivity of 91db = 124. However on 1000 watts and 2 10" in a ported box i hit 138.9 on a term lab meter (official meter of db drags) and the box was to small for the speakers, and the starting sensitivity was only 82. Something just don't add up, with 2 15"'s seeing 2000 watts i should be in the 145150 on the termlab meters.
anyone know how to figure out what the theoretical SPL should be. I use winisd and it says the same 124db, and only like 110db on my 10's. 
3rd July 2006, 01:54 PM  #2 
diyAudio Member

In house and car there are room and cabin gain, these increase spl tenfold up an extra 10  30 db, for reasons I cant fully explain, but I know is right

5th July 2006, 07:45 AM  #3 
diyAudio Member
Join Date: Feb 2004
Location: Chinook Country.Alberta

ah.. a dB question ...
the formula for sound pressure level increase ,not power is db=20*log(p2/p1)so for example. if p2=say 100 watts, p1=1 watt, log of 100/1 is the same as log 100(essentially)=2, then 20 * 2 is 40, therefore total accoustical db =91+40=133
similarly 1000watts=:136 dBfor power db the formula is dB=10*10log(p2/p1) this is with the assuption that Z=2 ohms total..not 1/2 ohm of course. Q?: what does SS use for spl, 91 is posted but is that 2 Ohms (voice coils in series) or 1/2 ohm (VC in ll)? also in house there may be as much as 9db "room gain" and upto 12 or 15 db "car gain"..as previously stated.
__________________
stew ☮ "A sane man in an insane world appears insane." 
5th July 2006, 07:51 AM  #4 
diyAudio Member
Join Date: Feb 2004
Location: Chinook Country.Alberta

db
nt
__________________
stew ☮ "A sane man in an insane world appears insane." 
Thread Tools  Search this Thread 


Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
is it correct to calculate OTL?  sam8888ysl  Tubes / Valves  15  26th November 2007 05:48 AM 
How to calculate the BL of driver  p_eric  Subwoofers  21  3rd November 2006 11:52 AM 
help ! how to calculate??????????  bogdan_borko  Solid State  3  18th January 2006 10:15 PM 
Calculate BL  Dave Jones  MultiWay  19  8th May 2004 01:16 AM 
Calculate BL?  Dave Jones  MultiWay  3  4th May 2004 08:04 PM 
New To Site?  Need Help? 