can i get some opinions on what size boxes (cu.feet) these will be mst acurat in - diyAudio
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Old 9th April 2004, 01:03 AM   #1
zuki is offline zuki  United States
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Default can i get some opinions on what size boxes (cu.feet) these will be mst acurat in

sealed box specs

i just want to know which box volume they will test/measure best in. (cubic feet figures) sealed

or any other opinions

thank you

#1

T / S Parameters
Qts : 0.38
Qes : 0.43
Qms : 3.60
Vas : 78 L
Sd : 355.41 cm^2
XMag : 12.5 mm
XSus : 18.9 mm
XMax : 12.5 mm
MMd : 124 g
Re : 2.39
Fs : 21 Hz
Bl : 16.9



#2


T / S Parameters
Qts : 0.30
Qes : 0.34
Qms : 3.16
Vas : 181.65 L
Sd : 545.42 cm^2
XMag : 12.5 mm
XSus : 18.9 mm
XMax : 12.5 mm
MMd : 178 g
Re : 2.39
Fs : 17 Hz
Bl : 21
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Old 9th April 2004, 01:54 AM   #2
Wizard of Kelts
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Hard to say what is the "best" box for a woofer. Here are a cpuple of decent suggestions.


For #1:
If you want to do sealed, then a good box would be 42 liters, for a Qtc of .65, an Fc of 36 Hz and an F3 slightly above that.

It will also do well ported in a 73 liter box tuned to 21 Hz, with an F3 of 21 Hz.



For speaker #2:
For sealed,
1.4 cu ft for a Qtc of 0.71 and an F3 or 40 Hz,
or
Ported- 3 cu ft tuned to 23 Hz with a 4 in diameter vent 18 in long, F3 at 23 Hz.

Here is the chart for speaker #2. Closed box in red, vented box in blue:
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File Type: gif zuki's speaker no 2, april 8 b.gif (12.9 KB, 207 views)
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Old 9th April 2004, 02:28 AM   #3
zuki is offline zuki  United States
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convert litres to cf

i thought the sealed box would/could be smaller
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Old 9th April 2004, 04:41 AM   #4
zuki is offline zuki  United States
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can i have help converting litres to cubic feet

thank you.

as the #'s behind the decimal seem to make me wonder if i am not making the box the right size.
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Old 9th April 2004, 05:03 AM   #5
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Here

http://www.sciencemadesimple.net/conversions.html

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Old 9th April 2004, 05:20 AM   #6
Nanook is offline Nanook  Canada
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Default are u on drugs?

what program are you using.? Win ISD indicates a 32l box, f3=41Hz, Qtc=.721 for driver #1 sealed.
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Old 9th April 2004, 05:53 AM   #7
Wizard of Kelts
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Sorry, Zuki, you did ask for cubic feet. I converted the second, but not the first.

One cubic foot equals 28.3 liters.

So 42 liters equals 42/28.3 = 1.48 cu ft. That's for the sealed box for #1.

73 liters equals 73/28.3 = 2.58 cu ft. That's the ported box for #1.
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Old 9th April 2004, 06:13 AM   #8
Wizard of Kelts
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Default Re: are u on drugs?

Quote:
Originally posted by Nanook
what program are you using.? Win ISD indicates a 32l box, f3=41Hz, Qtc=.721 for driver #1 sealed.
Nanook:

No, I'm not on drugs at the moment. Why, you got any handy?


In absolutely no shape, size or form do I feel compelled to take any programs's recommendation. I have been using formulas to design loudspeaker boxes before I ever owned a computer. In the case of driver #1, I used no programs at all.

When Zuki asked for a good sealed box, I basically had my choice of any final Qtc between 0.5 and 1.0. For convenience's sake, I decided to to choose a sealed box of 1.5 cubic feet, which yielded a highly satisfactory Qtc of 0.65, according to the well-known formula below. This formula, while an approximation, is used by Small and others before him to figure final Qtc and Fc.

As for the vented box, the Qts of 0.38 made a program unnecessary. The Classic Tuned Box, according to Thiele and Small, is like this:

Take a speaker of Qts of 0.38. Put into a box equal to it's Vas, tune to Fs and you get an F3 = Fs. So that is what I did. No programs necessary. Unfortunately, I misread the Vas as being 73 liters, when it is in fact 78 liters. It would have worked well in a box of 73 liters, anyway. However, I should have written a 78 liter box, not a 73 liter one.
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Old 9th April 2004, 06:32 AM   #9
Wizard of Kelts
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Quote:
Originally posted by zuki

i thought the sealed box would/could be smaller
Zuki:

Sure, you can make the sealed boxes smaller. Like I said, the desirable choices are between a final Qtc of 0.5 and 1.0. That leaves a lot of lattitude.

For #1, a sealed box of 1 cubic feet will yield a final Qtc of 0.74, an Fc of 41 Hz and an F3 a touch below that.

For #2, a sealed box of 1 cubic foot will yield a Qtc of 0.82, an Fc of 46 Hz and an F3 a couple of Hz below that. Very workable, if that is what you want.
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Old 9th April 2004, 12:17 PM   #10
Nanook is offline Nanook  Canada
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Default R U on drugs?

kelticwizard:

certainly no disrespect intended regarding drugs.

I tend to always aim for Qtc = .707, thus my recomend of a 32 l sealed box. The programs generally are all based on the same work. Obviously an overly warm sound can be delivered as in the infamous LS3/5 (Qtc about 1.24 or so if memory serves me correctly---something I no longer take for granted).

Anyways, again certainly no disrespect was intended.
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