Power ratings demystified - AVS | Home Theater Discussions And Reviews
Baselworld is only a few weeks away. Getting the latest news is easy, Click Here for info on how to join the Watchuseek.com newsletter list. Follow our team for updates featuring event coverage, new product unveilings, watch industry news & more!


Forum Jump: 
 
Thread Tools
post #1 of 13 Old 02-14-2010, 12:47 PM - Thread Starter
Advanced Member
 
Th3_uN1Qu3's Avatar
 
Join Date: Oct 2008
Location: Bucharest, Romania
Posts: 714
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Here's some food for thought illustrating pro audio test standards. Now you know exactly how PA speakers are rated (notice the bass slope on all the tests, so they're obviously not rated for HT use ). http://www.sonidoprofesional.com/doc...erhandling.htm

I'll try to add to this thread any info i can find about audio power ratings. I'll try to find a document explaining amp power ratings as well.

Quote:
Originally Posted by Ivan Beaver
The nice thing about standards is that there are so many to choose from.
Th3_uN1Qu3 is offline  
Sponsored Links
Advertisement
 
post #2 of 13 Old 02-14-2010, 12:57 PM
AVS Addicted Member
 
LTD02's Avatar
 
Join Date: Oct 2003
Posts: 17,894
Mentioned: 59 Post(s)
Tagged: 0 Thread(s)
Quoted: 1073 Post(s)
Liked: 1475
maybe not all pa are the same? footnotes on page 2 of this jbl 'sub' seem more rigorous than what you have posted.

http://www.jblpro.com/catalog/suppor...pe=3&docid=626

Listen. It's All Good.
LTD02 is online now  
post #3 of 13 Old 02-14-2010, 01:20 PM - Thread Starter
Advanced Member
 
Th3_uN1Qu3's Avatar
 
Join Date: Oct 2008
Location: Bucharest, Romania
Posts: 714
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
That's some nice explanations there. Lemme see if i can find another reference that says the same.

Quote:
Originally Posted by Ivan Beaver
The nice thing about standards is that there are so many to choose from.
Th3_uN1Qu3 is offline  
post #4 of 13 Old 02-14-2010, 03:27 PM
AVS Special Member
 
Ivan Beaver's Avatar
 
Join Date: Dec 2005
Posts: 1,650
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 8 Post(s)
Liked: 47
The nice thing about standards is that there are so many to choose from

Danley Sound Labs

Physics-not fads
Ivan Beaver is offline  
post #5 of 13 Old 02-14-2010, 05:13 PM - Thread Starter
Advanced Member
 
Th3_uN1Qu3's Avatar
 
Join Date: Oct 2008
Location: Bucharest, Romania
Posts: 714
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by Ivan Beaver View Post

The nice thing about standards is that there are so many to choose from

It was about time for me to change my sig.

Quote:
Originally Posted by Ivan Beaver
The nice thing about standards is that there are so many to choose from.
Th3_uN1Qu3 is offline  
post #6 of 13 Old 02-14-2010, 06:14 PM
AVS Special Member
 
kryptonitewhite's Avatar
 
Join Date: Aug 2008
Posts: 4,602
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 12
Quote:
Originally Posted by Ivan Beaver View Post

The nice thing about standards is that there are so many to choose from

amen
kryptonitewhite is offline  
post #7 of 13 Old 02-14-2010, 06:40 PM
AVS Special Member
 
stgdz's Avatar
 
Join Date: May 2002
Location: MNsnowta in april :(
Posts: 2,188
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 14
So what is the general rule of thumb for db drop off per meter?
stgdz is offline  
post #8 of 13 Old 02-14-2010, 09:38 PM
AVS Special Member
 
cavu's Avatar
 
Join Date: Apr 2005
Location: CANADA
Posts: 6,886
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 13
Quote:
Originally Posted by stgdz View Post

what is the general rule of thumb for db drop off per meter?

Loss of what per meter of what??

Electricity in copper?

Sound in air??

In either case, it depends.

If it is sound in air, check HERE.

"The greatest obstacle to discovery is not ignorance  it is the illusion of knowledge." - Daniel Boorstin
"Our lives begin to end the day we become silent about things that matter.
" - MLK

cavu is offline  
post #9 of 13 Old 02-15-2010, 04:56 AM
AVS Special Member
 
Ivan Beaver's Avatar
 
Join Date: Dec 2005
Posts: 1,650
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 8 Post(s)
Liked: 47
Quote:
Originally Posted by stgdz View Post

So what is the general rule of thumb for db drop off per meter?

Assuming a free field (outside) and a device that is small in relation to the wavelength being reproduced (ie not a long line array), you lose 6dB per doubling of distance.

When the device becomes large-all sorts of things start to change.

It is not about lose per meter. but rather a ratio of distances involved.

The loss from 1M to 2M will be 6db, but from 100-101M will not even be noticed.

Danley Sound Labs

Physics-not fads
Ivan Beaver is offline  
post #10 of 13 Old 02-15-2010, 11:43 AM
AVS Special Member
 
stgdz's Avatar
 
Join Date: May 2002
Location: MNsnowta in april :(
Posts: 2,188
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 14
stgdz is offline  
post #11 of 13 Old 02-15-2010, 04:49 PM
 
mjg100's Avatar
 
Join Date: Dec 2006
Posts: 9,112
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 14
Quote:
Originally Posted by Th3_uN1Qu3 View Post

It was about time for me to change my sig.

Thank you.
mjg100 is offline  
post #12 of 13 Old 02-16-2010, 10:47 AM
AVS Special Member
 
Looneybomber's Avatar
 
Join Date: Sep 2006
Location: Lawrence, KS
Posts: 4,668
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 23
Quote:
Originally Posted by Th3_uN1Qu3 View Post

It was about time for me to change my sig.

I think there's too many folks with quotes from Ivan in their sigs. Doesn't Penngray also have an Ivan quote?

YID DIY
Looneybomber is offline  
post #13 of 13 Old 02-16-2010, 11:22 AM
AVS Special Member
 
Drew Eckhardt's Avatar
 
Join Date: May 2001
Location: Sunnyvale, CA USA
Posts: 2,674
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 14
Quote:
Originally Posted by stgdz View Post

thanks ivan that is what I was looking for.

Although the 6dB number is not appropriate for determining SPL in enclosed reverberant spaces like a home theater or concert hall.

If you were in a uniform diffuse field the SPL would not drop 3dB regardless of how far you moved beyond the critical distance.

Unfortunately, that situation is also not applicable.

In practice, real spaces have total SPL 3dB over the direct sound at what would be the "critical distance" and tend to average a 3dB draw down rate per distance doubling.
Drew Eckhardt is offline  
Sponsored Links
Advertisement
 
Reply DIY Speakers and Subs

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off