how to measure qtc after building enclosu
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=127163
Printed Date: May 12, 2025 at 3:07 PM
Topic: how to measure qtc after building enclosu
Posted By: teenkertoy
Subject: how to measure qtc after building enclosu
Date Posted: April 29, 2011 at 3:01 AM
There are countless calculators, spreadsheets and programs to model the response and qtc of a sealed enclosure. However, I cannot find any information about how to measure qtc of a speaker/enclosure system after it has been built.
For example, I know the transient response of a sealed system is directly influenced by the internal volume, but how can you measure when you get the volume just right, and achieve critical damping of qtc=0.5? (or any other goal you want for that matter)
I know resonant frequency can be found by plotting impedance vs frequency, and I imagine there is a similar electrical measurement to find qtc (or perhaps an acoustic measurement?)
-J
------------- Malcom: "This is the captain. We have a...little problem with our engine sequence, so we may experience some slight turbulence and then...explode."
Jayne: "We're gonna explode? I don't wanna explode.
Replies:
Posted By: DYohn
Date Posted: April 29, 2011 at 6:02 PM
If you have an RTA, you need to measure nearfield f3, then use your calculated Fc value and the Qts of the driver in this formula: Qtc = (Fc X Qts)/f3
Or use this calculator.
https://www.ajdesigner.com/phpsubwooferclosed/resonance_frequency_equation_qtc.php ------------- Support the12volt.com
Posted By: teenkertoy
Date Posted: April 29, 2011 at 9:07 PM
Thanks DYohn, this is just what I was looking for.
-J
------------- Malcom: "This is the captain. We have a...little problem with our engine sequence, so we may experience some slight turbulence and then...explode."
Jayne: "We're gonna explode? I don't wanna explode.
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