That depends on what he's looking for. If he's looking for the most low end extension then 200 liters tuned to 15 hz would outperform 100 liters tuned to 20 hz. A 15 hz tuning won't require a hi-pass filter while a 20 hz tuning will. With 700 watts of power there's a 10 db difference between the two at 15 hz.
Hi,
No it won't well in practical reality, your just chasing simulator numbers.
rgds, sreten.
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Thanks for the link sreten, nice website!
So you mean that the WinISD calculations above a certain volume enclosure are not correct? And that it is not possible or when you do it anyway it will sound like crap?
I really thought that with 2 x 700WRMS, 15" and a big XMax you could get kinda low, at least lower then most available subwoofers...
Yes and no. WinISD is accurate at showing basic output but does not calculate transient response. It does calculate group delay which does correlate some what to transient response but not completely.
The Q of a chamber and driver, Qtc, will tell you more about what it will sound like vs. how loud it gets (spl). A too large box (Q below .5) will be more sensitive at low frequencies but the driver will have less air-spring to help it and tends to sound muddy or dull than a box with a Q above .5
Conversely, a box with a high Q, above .8 will sound sharper but also boomy as the bandwidth is narrow in comparison. You have to find something in the middle that you like. This cannot be explained only experience will show you what you like.
p.s. i still think those two drivers in sealed boxes with a little eq. would sound great.
p.p.s BR boxes do have Q's but most people tend to ignore them. (i don't know why. maybe it's too complex
)
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what are the dimensions of the room, I can sim the room and give you a rough estimate.
edit: I'll explain how to as well.
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ok, if the room is sealed you will get about +3-6db gain below 35Hz, if the room has one open door you'll get ~+2db gain if there are lots of openings... no gain for you
This is the simplified good enough version (the complex version includes ray tracing, decay times and a bunch of other boring stuff), to figure this you calculate the primary room modes ( Room Mode / Standing Wave Calculator ) the average of the three primary modes will give you the gain Low pass frequency, which in your case 35.0333Hz. Below that frequency the low frequency waves will start to "stack" which is generally referred to as room gain.
edit: good reference : http://www.silcom.com/~aludwig/Room_acoustics.html
This is the simplified good enough version (the complex version includes ray tracing, decay times and a bunch of other boring stuff), to figure this you calculate the primary room modes ( Room Mode / Standing Wave Calculator ) the average of the three primary modes will give you the gain Low pass frequency, which in your case 35.0333Hz. Below that frequency the low frequency waves will start to "stack" which is generally referred to as room gain.
edit: good reference : http://www.silcom.com/~aludwig/Room_acoustics.html
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Waw, Thanks for your efforts! At the moment the room is very leaky... And only a single glas window (2-3mm) separates the Room from the street
That should change but it will not right away happen, the plan is ever to soundproof the place and use real seat and so on.
Maybe I should use one sub in a sealed and on in a BR, I'm going to sleep and dream about...
That should change but it will not right away happen, the plan is ever to soundproof the place and use real seat and so on.
Maybe I should use one sub in a sealed and on in a BR, I'm going to sleep and dream about...
Actually using a combination of sealed and ported subs worked well in my room.'
My subs were really cheap ($99- each ) 10 inch HT units but the price was right at the time, 4 of them in the room worked OK but when I sealed the ports in a couple the overall sound depth improved "in my room" so worth looking at
My subs were really cheap ($99- each ) 10 inch HT units but the price was right at the time, 4 of them in the room worked OK but when I sealed the ports in a couple the overall sound depth improved "in my room" so worth looking at
Hi,
The calculations might be correct, but the reality is less likely to be correct,
taking any simulator to its extremes is not a good idea, extreme alignments
require very accurate parameters, sensible alignments can handle some
variation in the actual parameters.
Whilst some might mess around buildling small vented speakers with Vbox
much larger than Vas, the idea of hoping a 200L box works well for a
80L Vas driver and building it to find out is far more hard work.
Make sure your not modelling nonsense, excursion limits are included.
rgds, sreten.
Greets!
Well, using Keele's extended bass self [EBS] alignment, Vb = 2.6*Vas = 215.8 L with a Fs/1.52 = 21.7 Hz Fb, so this is the absolute lowest I'd go in a BR.
Note that he assumes a 0.625 Qts, so in theory some series resistance would be required, using up some system efficiency.
Such alignments usually need corners to keep the drivers from distorting too much when pushed plus thermal power compression will lower peak SPL capability.
All things considered then, at this net Vb you're better off overall with some form of TL or horn where you can tune them up to an octave below Fs.
GM
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