0.707 or 0.85 Qtc?
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=20935
Printed Date: July 12, 2025 at 7:44 PM
Topic: 0.707 or 0.85 Qtc?
Posted By: paper
Subject: 0.707 or 0.85 Qtc?
Date Posted: November 03, 2003 at 10:07 AM
I want to build a sub(sealed) box for my car. Which should I use a 0.707 or 0.85 Qtc? Or maybe you have a better Qtc based on the experiment. Please tell me.
Replies:
Posted By: bberman1
Date Posted: November 03, 2003 at 10:22 AM
What make and model sub are you referring to?
Posted By: specialblendj
Date Posted: November 03, 2003 at 10:23 AM
OK, do you know what you are talkin about? Qtc is a t/h parameter of speakers, in this case subwoofers. The qtc of the sub you have will be a determining factor in the type of enclosure you want to build. enclosures don't have a qtc, as far as i know.
Posted By: paper
Date Posted: November 03, 2003 at 10:34 AM
Here is my subs spec Is this a good sub( for SPL not SQ)
Posted By: bberman1
Date Posted: November 03, 2003 at 11:13 AM
This is defiantly not a SPL sub. The Xmax which is how much the cone can move in one direction is 4 mm or just under 3/8 of an inch. The higher the Xmas the more air the sub can move, which translates into more SPL. From the specs it doesn’t sound like a very good SQ woofer either. What make and model is it?
Posted By: forbidden
Date Posted: November 03, 2003 at 11:19 AM
Dude, sometimes spec's are not the be the all end the all. If you r doin a spl setup, go into a specialty retailer as they are the ones to put you on the right path. You will need to do a sinewave sweep to find the loudest resonant frequency of your vehicle and then build and tune the box for that loudest resonant frequency with the appropriate speaker. Personally, these things absolutely wail, but the trade off is that if this is your daily driver, then you will get mighty bored with this in a hurry. If you want to build a system that plays loud that you can listen to, tell the dealer this. Be aware that volume levels in excess of 110db will cause permanent hearing damage. The box in this case will have the most to do with the output capabilities of the sub. Biuld it too small and you get nice tight bass but no depth, build it to big and the amplifier will lose control of the motion of the driver, and you will have no tightness to the bass, which btw will probably sound like a wet fart. Build that box bang on and hold on, you should get shaken like a bowl of jello in an earthquake.
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