calculating Q for spl due to RLC notch filter - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way

Multi-Way Conventional loudspeakers with crossovers

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
Reply
 
Thread Tools Search this Thread
Old 21st August 2009, 01:30 AM   #1
Dave R is offline Dave R  United States
diyAudio Member
 
Dave R's Avatar
 
Join Date: Aug 2006
Default calculating Q for spl due to RLC notch filter

Is there such a thing as a "Q" for the notch in spl caused by a parallel RLC filter, and if so is it calculated similar to the Q for the notch in the impedance? I can't seem to find this defined anywhere.

Numbers below are for example only.

freq atten
(Hz) (dB)
---- ------
6184 -2.00
7039 -2.83
9016 -4.00 << (notch center freq)
11548 -2.83
13145 -2.00

Is it simply calculated at the point where the attenuation is .707 x SPL@ notch?

In this case where atten = 4.00 x .707 = 2.83, I'd be inclined to calculate Qspl as follows:

Qspl = [9016/(11548-7039)] = 2.0

What I'm leading toward is trying to size up the RLC values for a notch filter, when the Q for spl can be obtained from measured data.

Dave R
the 200% Norske
__________________
- Dave R
the 200% Norske
  Reply With Quote
Old 21st August 2009, 01:58 AM   #2
infinia is offline infinia  United States
diyAudio Member
 
infinia's Avatar
 
Join Date: May 2005
Location: Californication
Q is defined for any second order system response ie any RLC. So you would measure it the same way for a speaker driver or a sallen key filter stage. Q = central freq /half power BW


Hint use 3 dB away from central point not 0.707
If meas. using voltage then 0.707 is correct.
Vp=1 V then 20log*1/0.707= 3 dB
__________________
like four million tons of hydrogen exploding on the sun
like the whisper of the termites building castles in the dust

Last edited by infinia; 21st August 2009 at 02:20 AM.
  Reply With Quote
Old 21st August 2009, 05:59 PM   #3
Ron E is offline Ron E  United States
diyAudio Member
 
Ron E's Avatar
 
Join Date: Jun 2002
Location: USA, MN
Quote:
Originally Posted by Dave R View Post
Is there such a thing as a "Q" for the notch in spl caused by a parallel RLC filter, and if so is it calculated similar to the Q for the notch in the impedance?
See attached. Have fun.
Attached Files
File Type: zip NOTCH.zip (23.0 KB, 32 views)
__________________
Our species needs, and deserves, a citizenry with minds wide awake and a basic understanding of how the world works. --Carl Sagan
Armaments, universal debt, and planned obsolescence--those are the three pillars of Western prosperity. Aldous Huxley
  Reply With Quote
Old 22nd August 2009, 02:56 PM   #4
Dave R is offline Dave R  United States
diyAudio Member
 
Dave R's Avatar
 
Join Date: Aug 2006
Thanks Ron. Nice little spreadsheet.
__________________
- Dave R
the 200% Norske
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Notch filter godless Multi-Way 5 22nd April 2008 10:26 AM
need help wana change 60-Hz twin-T notch filter to 279 Hz filter prorms Solid State 0 10th February 2008 12:38 AM
Can Zaphs notch filter be used without the BSC filter? GuyPanico Full Range 0 21st July 2007 02:27 AM
Notch filter qguy Multi-Way 3 26th October 2006 10:26 PM
Does anyone have a notch filter for NSB's? GuyPanico Multi-Way 6 21st July 2006 03:06 AM


New To Site? Need Help?

All times are GMT. The time now is 01:11 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2