A-weighted; C-weighted SPL?

 

Bronze Member
Username: Mattellermets

Danville, IL US

Post Number: 51
Registered: Sep-04
alllrighty. first thing. its 3:45am and i am curious, but dont feel like searching the vast internet for this answer... although im not 100% sure this is the correct branch of the forum for the question, oh well here goes:

what do "weightings" mean when it comes to car audio?

i was at radioshack, playing with the digital spl meter... i can easily max it out (127db) inside my s10 with shivas on 150w rms each... with the switch on C-weighted i believe

if i remember correctly, having it set for A-weighting gave me under 120db (all interior meterings... actual listening positions)

what does this mean, what is it for, and how does it work? :-)
 

Bronze Member
Username: Wojopro

Post Number: 39
Registered: Nov-04
BUMP
 

Gold Member
Username: Glasswolf

NorthWest, Michigan USA

Post Number: 6264
Registered: Dec-03
C weighting is a curve formulated to replicate the natural curve of human hearing. In other words, using a pink noise signal generator, a C weighted curve would "sound" flat to the human ear.

This explains it easier tahn I could, not being able to graph things here myself
http://www.norsonic.com/web_pages/correlation.html

let me know if I can further explain any of it


 

Bronze Member
Username: Wojopro

Post Number: 43
Registered: Nov-04
So which one would a tournament use??? A or C???
 

Bronze Member
Username: Mattellermets

Danville, IL US

Post Number: 52
Registered: Sep-04
awesome. that page told me exactly what i wanted to know... thanks.

so is there actually a formula for determining the center of the band of frequencies that produce the most SPL in a certain environment? that would be kinda neat.. if i'm lucky, it'll be something like what i'll learn in physics 106 and 235 next semester.. hehe
 

Gold Member
Username: Glasswolf

NorthWest, Michigan USA

Post Number: 6293
Registered: Dec-03
C weighted curves are used on an RTA at events.

Yes, you can find the sympathetic or resonant frequency of the car's cabin. That's the most efficient point to tune a sub's ports to on a ported or bandpass enclosure. This will use cabin gain coupled with the peak efficieny of the tuned ports to produce the best SPL.
However, this also is usually around 55-70Hz, and to the human ear, it'll sound like two cats sex0ring. Not a real pleasant tuned frequency for subs.. loud, but very boomy and high.
for best SQ, you usually shoot closer to the Fs of the speaker, which tends to be around 25-32Hz.
nice and deep and works in conjunction with the free air resonant frequency of the driver itself.
 

Bronze Member
Username: Mattellermets

Danville, IL US

Post Number: 53
Registered: Sep-04
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