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Recommended QTS for infinite baffle Car subs 0.5 to 0.7 or higher than 0.7??
Recommended QTS for infinite baffle Car subs 0.5 to 0.7 or higher than 0.7??
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Old 11th October 2019, 06:23 AM   #1
audfrknaveen is offline audfrknaveen  India
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Default Recommended QTS for infinite baffle Car subs 0.5 to 0.7 or higher than 0.7??

Hello all,

What is the Recommended QTS for infinite baffle subwoofers for my car ???

As far as I know, high Qts is needed, but is it in the range of 0.5 to 0.7 or higher that 0.7 is recommended ???

Any suggestions please....
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Old 11th October 2019, 07:12 AM   #2
picowallspeaker is offline picowallspeaker  Italy
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I doubt that you can find an infinite baffle application inside a car.
The concept of IF applies to the propagation of sound around the box, as the model is a monopole with no boundaries. Once you move from 4pi steradians, you'll get reinforcement from the boundaries - according to the wavelenght, of course, and that explains why it's easy to talk about pressurization inside a car.

Qtc indicates the kind of rolloff and what happens at the 'knee' around Fb.
It's mostly Fs related, as you want to design to have the lowest extension with good punch, so highish Q against 0.7 or lower.
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Old 11th October 2019, 08:17 AM   #3
audfrknaveen is offline audfrknaveen  India
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please see the attached image.
Trying to find suitable Qts drivers for this application.
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File Type: jpg ib subs.jpg (121.1 KB, 95 views)
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Old 11th October 2019, 11:31 AM   #4
picowallspeaker is offline picowallspeaker  Italy
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I see a finite baffle, about 1x0.3m ; two huge woofers and two tweeters at the sides. A back chamber with high losses. Qts is derived from electrical and mechanical Q. Any speaker designed for car should do the job. For subwoofers, the restricted BW calls for lower sensitivity, so a dedicated amplifier with electronic crossover is the norm...or you're gonna go with the example that you gave, 25 cm woofers, that have about 90 dB/W/m sensitivity.
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Old 11th October 2019, 12:07 PM   #5
Sonce is offline Sonce  Macedonia
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Quote:
Originally Posted by audfrknaveen View Post
please see the attached image.
Trying to find suitable Qts drivers for this application.
Qts around 0.7 would be fine.
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Old 11th October 2019, 01:41 PM   #6
audfrknaveen is offline audfrknaveen  India
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Currently I'm looking to buy this driver as it is easily available in my area.

TS-W306R | Pioneer

The Qts is slightly higher than 0.7
That's why I'm wondering is this ok for my application.

Thank you so much for the inputs everyone !!!
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Old 11th October 2019, 05:51 PM   #7
audfrknaveen is offline audfrknaveen  India
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Quote:
Originally Posted by picowallspeaker View Post
I see a finite baffle, about 1x0.3m ; two huge woofers and two tweeters at the sides. A back chamber with high losses. Qts is derived from electrical and mechanical Q. Any speaker designed for car should do the job. For subwoofers, the restricted BW calls for lower sensitivity, so a dedicated amplifier with electronic crossover is the norm...or you're gonna go with the example that you gave, 25 cm woofers, that have about 90 dB/W/m sensitivity.
You are right !!!
Ideally it's a finite baffle with high losses. But I want to go this way to have more space for luggage. It's. a compromize
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Old 11th October 2019, 06:08 PM   #8
picowallspeaker is offline picowallspeaker  Italy
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That pioneer sub is huge! I wouldn't put it in my room, go figure in a car's inside!
High losses is a joke, I imagine pressure would make the sound spill from every fessure!
And what about the rest of the set-up?
Subwoofer covers only the first octave ( even less) and can be easily be forgotten when/if the system plays fine.
OR
If you wish to use two of them as woofers, those are said to work good till 125 Hz, so you need two fullrange or midwoofer and tweeter to play the rest ( of audio spectrum).
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Old 11th October 2019, 06:12 PM   #9
tsmith1315 is offline tsmith1315  United States
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High Qts isn't as important as you'd think in this situation. Reasonable efficiency and excursion is. I've had great success with low Qts (0.2-0.3), low Fs drivers in rear package trays.

I consider this much less of a compromise than a boxed woofer stuffed inside the trunk, you may be pleasantly surprised.
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Old 11th October 2019, 07:23 PM   #10
GM is offline GM  United States
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Right, Ideally we want a flat response, so need a 0.707 Qtc alignment to blend to the cabin's 2nd order rise, but need to measure the cabin gain to figure out what driver Fs, box tuning [Fb] is required to match up to it, which often requires a lower Qts driver than one would think and why premium JBL, etc., mobile audio [sub] woofers have < 0.5 Qts to match up with differing size cabins, rear box volumes [Vb].

That said, with the amps, electronics available today, probably best overall to use a ~0.5 Qts driver for transient perfect response as the mean and let cabin gain combined with parametric EQ allow sufficient latitude for tailoring it to one's 'taste' based on windows up/down and/or different music genres.

GM
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