Hi all !!!
This is my first trial build. I have done some work in BassBox Pro and would like some help analysing the Graph Plots for my design..
I was trying to go down to or near 40hz but the best am geting is 49hz. thats fine for now but what bout the other detail in the plot
pics...
http://postimage.org/gallery/vdzb5x4/
This is my first trial build. I have done some work in BassBox Pro and would like some help analysing the Graph Plots for my design..
I was trying to go down to or near 40hz but the best am geting is 49hz. thats fine for now but what bout the other detail in the plot
pics...
http://postimage.org/gallery/vdzb5x4/
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The box you show is designed for maximum output with flat response.
You can tune the box lower using a longer port if you want lower extension, but the box will then roll off slightly in response down low, Hoffman's Iron Law at work.
If you prefer the extension of another 1/3 octave and can live with the reduced upper output, go for it.
You can tune the box lower using a longer port if you want lower extension, but the box will then roll off slightly in response down low, Hoffman's Iron Law at work.
If you prefer the extension of another 1/3 octave and can live with the reduced upper output, go for it.
Flat response is a good thing, but the response of your sub in room will not be flat.
Placing the sub in a corner or near walls will increase low response more than upper response.
Many (myself included) would prefer lower extension with slightly less output, to a flat response that rolls off like a rock an octave above the low note on a grand piano
.Art
The link is Postimage.org / gallery - Ca R, CD, Gd, Ma P, Mei P, Na R, Ph R, Si
Art?
So lower extension it is then... What next?
Art?
So lower extension it is then... What next?
Make some sawdust, experiment with different tunings, report back with what your preference is.
Art
Hi Guys. just a quick up date.... I have mod the box design a bit. Made it a 18" cube with a sigle brace (this is a first build on a budget). It now goes to 47hz flat.
I was lucky to get my local DIY store to do the cuting. So now ...... some glue, screws, sealant..
Some CAD pics...
I was lucky to get my local DIY store to do the cuting. So now ...... some glue, screws, sealant..
Some CAD pics...
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Hello all. After much inactivity am going this Sub building one last Go!!.
The driver I am using is Skyteck\Qtx 902.222 mainly because of the price.
Quick Stats; Fs.29hz - Vas.129L - Xmax.6mm - Sd.506cm2 - Qes.0.71
Re.71mH - Qms.1.58 - Spl. 88.5.
The Amp is courtesy of my current Wharfedale Topaz Sw12 (150w).
Software is BassBox Pro6.
The aim is a Sealed box of minimal proportions. Originally I came up with a 18'' cube, had the sheets cut as such but after seeing the sheets mucked up decided that was too big.
So I began thinking of ..
1. 14'' cube. would i be able to get good results by stuffing to get a more respectable Vb. BassBox doesn't seem to account for the effect of stuffing to well.
what are the general rule of thumb regarding amount of stuffing?
2. A 18x14x14'' Down firing Box, again with use of stuffing.
3. A 18x18x14 Front mounted
What are your thoughts, guidance, discipline, advice?
Thank you for taking the time to read this an for any replies....
The driver I am using is Skyteck\Qtx 902.222 mainly because of the price.
Quick Stats; Fs.29hz - Vas.129L - Xmax.6mm - Sd.506cm2 - Qes.0.71
Re.71mH - Qms.1.58 - Spl. 88.5.
The Amp is courtesy of my current Wharfedale Topaz Sw12 (150w).
Software is BassBox Pro6.
The aim is a Sealed box of minimal proportions. Originally I came up with a 18'' cube, had the sheets cut as such but after seeing the sheets mucked up decided that was too big.
So I began thinking of ..
1. 14'' cube. would i be able to get good results by stuffing to get a more respectable Vb. BassBox doesn't seem to account for the effect of stuffing to well.
what are the general rule of thumb regarding amount of stuffing?
2. A 18x14x14'' Down firing Box, again with use of stuffing.
3. A 18x18x14 Front mounted
What are your thoughts, guidance, discipline, advice?
Thank you for taking the time to read this an for any replies....
1.445cf is what bbpro comes up with for me using your spec.
You can calculate the sag of a driver from:
- 24,849 is a constant value based on the relationship of acceleration due to gravity and Pi.
- Xmax is the maximum linear excursion of a loudspeaker voice coil while remaining within the magnetic flux field (mm).
- Fs is the free-air resonant frequency of the woofer (Hz).
= 24,849/ (6 x 841)
= 24,849/5046
=4.92%
As a general rule of thumb, any time the sag exceeds 5% of the driver's Xmax, it's not recommended for a down-firing subwoofer application.
You can calculate the sag of a driver from:
Percentage of Sag = 24,849 / ( Xmax * Fs²)
where- 24,849 is a constant value based on the relationship of acceleration due to gravity and Pi.
- Xmax is the maximum linear excursion of a loudspeaker voice coil while remaining within the magnetic flux field (mm).
- Fs is the free-air resonant frequency of the woofer (Hz).
= 24,849/ (6 x 841)
= 24,849/5046
=4.92%
As a general rule of thumb, any time the sag exceeds 5% of the driver's Xmax, it's not recommended for a down-firing subwoofer application.
Thanks for that Lil lesson Mr TBG..
I am still fooling around with BoxPro. ill get some graphs and cad up soon.
Whats wrong with modern men these days, Non of my friends has any sort of power tools.. lol. Ill just have to buy me a jig saw and a bench...
How goes the Tower.. that's my next Lil project when I (eventually) get this sub done.
I am still fooling around with BoxPro. ill get some graphs and cad up soon.
Whats wrong with modern men these days, Non of my friends has any sort of power tools.. lol. Ill just have to buy me a jig saw and a bench...
How goes the Tower.. that's my next Lil project when I (eventually) get this sub done.
http://www.commsandsound.com/thielesmall_902127.pdf
Hi,
its a skytronic 902.222 : 902.222 - for lower prices order online through Pricedumper.co.uk
1x Skytronic 902.222 12" 300W PP Cone Woofer Speaker | eBay
no idea what the real specs are .....
rgds, sreten.
Whats wrong with the Topaz 12" Driver ? Or its box for that matter.
Hi,
its a skytronic 902.222 : 902.222 - for lower prices order online through Pricedumper.co.uk
1x Skytronic 902.222 12" 300W PP Cone Woofer Speaker | eBay
no idea what the real specs are .....
rgds, sreten.
Whats wrong with the Topaz 12" Driver ? Or its box for that matter.
Yeah, WinISD calcs a base 0.895 Qtc, so damping it to max flat will bring it up to a ~58 Hz F3/~46.5 Hz Fb.
GM
Hi guys. Yes it is the Skytronic also called Qtx is some parts. It hoped to find some manufacture specs with the driver but there was nothing in the box.
Took me a good couple hours roaming the net to find some specs. Found quite a bit of data, then used BoxPro the cal the rest. As you said all seem to line up but accuracy is anyone's guess.
The Topaz driver was damaged beyond repair. But the box and amp are fine bar the completely snap off xover knob.
I did consider just using the Topaz box.... Until I stumbled across this website. Now I wanna DIY.
However I am trying for a compact enclosure.
Took me a good couple hours roaming the net to find some specs. Found quite a bit of data, then used BoxPro the cal the rest. As you said all seem to line up but accuracy is anyone's guess.
The Topaz driver was damaged beyond repair. But the box and amp are fine bar the completely snap off xover knob.
I did consider just using the Topaz box.... Until I stumbled across this website. Now I wanna DIY.
However I am trying for a compact enclosure.
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