yep... similar but the bandpass has still a lower f3, nice one.
now thats around 6.5 cuft.. (ouch)
and bandpass is from 54hz to 16hz +\- 3dB
I'd maybe need somehow a bit higher..
check this for a 83hz to 19 hz band pass
front chamber
0.706cutf fb 50hz
rear chamber
3cutf fb 17 hz
vs vented 6.5cuft @ 22 hz
the bandpass is as good as the vented but half its volume. now thats a deal!
what do you guys think of that one?
now thats around 6.5 cuft.. (ouch)
and bandpass is from 54hz to 16hz +\- 3dB
I'd maybe need somehow a bit higher..
check this for a 83hz to 19 hz band pass
front chamber
0.706cutf fb 50hz
rear chamber
3cutf fb 17 hz
vs vented 6.5cuft @ 22 hz
the bandpass is as good as the vented but half its volume. now thats a deal!
what do you guys think of that one?
that thing i stated above, i tried it today with 3 different apps,
winisd pro
winisd
and jbl speakershop
they all give me some strange results..
winisd pro tells me that a bandpass setup would suck compared to vented box..
winisd shows that a bandpass system would be a better size/performace ratio than vented
and jbl shows some very strange stuff....
any ideas wich one should i trust?
winisd pro
winisd
and jbl speakershop
they all give me some strange results..
winisd pro tells me that a bandpass setup would suck compared to vented box..
winisd shows that a bandpass system would be a better size/performace ratio than vented
and jbl shows some very strange stuff....
any ideas wich one should i trust?
Basically, I wouldn't trust any of them, because of the wierdness of your parameters.
I tried modeling this woofer back in the first thread you started. I used Bullock and White's freeware DOSBOX which, while a DOS program, still accurately computed such things as SPL from the parameters. DOSBOX came up with an SPL, all right, but had to change your Mms parameter to do it.
Then, of course, we tried using the parameters to calculate SPL ourselves. The woofer, by the manufacturer's own stated parameters, is .24% efficient instead of the manufacturer's stated .4% efficiency.
On the same chart where the manfacturer tells us the woofer is .4% efficient, the manufacturer lists other parameters that gurantee the speaker CANNOT be .4% efficient.
Apparently, a woofer with this particular combination of parameters cannot exist in the real world, and that is what is driving these programs nuts.
Here is the model using Subwoofer Simulator. This is running at 50 watts. I had to make a BL product rating, (unstated in the chart), to make this a smooth curve.
I tried modeling this woofer back in the first thread you started. I used Bullock and White's freeware DOSBOX which, while a DOS program, still accurately computed such things as SPL from the parameters. DOSBOX came up with an SPL, all right, but had to change your Mms parameter to do it.
Then, of course, we tried using the parameters to calculate SPL ourselves. The woofer, by the manufacturer's own stated parameters, is .24% efficient instead of the manufacturer's stated .4% efficiency.
On the same chart where the manfacturer tells us the woofer is .4% efficient, the manufacturer lists other parameters that gurantee the speaker CANNOT be .4% efficient.
Apparently, a woofer with this particular combination of parameters cannot exist in the real world, and that is what is driving these programs nuts.
Here is the model using Subwoofer Simulator. This is running at 50 watts. I had to make a BL product rating, (unstated in the chart), to make this a smooth curve.
Okay, here is the vented system of 6.5 cu ft and the bandpass system of 3.7 cu ft compared in Subwoofer Simulator, a great freeware program by our own member F4ier.
Subwoofer simulator can be downloaded here:
http://www.geocities.com/f4ier/speaker.htm
The shape looks a little different, but if you check the markings, you see the variation is not any greater than the other programs'.
I included cone excursion for the two systems. Both for frequency response and cone excursion, vented is in white, bandpass is in yellow.
This system is run at 30 watts.
A few observations. First, it is quite useless to build any system that goes down to 20 Hz with this system when your cone excursion is only 4 mm. As you see here, the cone excursion required even at 30 watts is twice your stated cone excursion. And 102 dB is not really hearable at 20 or 25 Hz-you want more than that to be worth your while. Now you know why Shivas and other fine subs have linear excursions over 12 mm.
Does your various programs have a place to fill in the Bl product? The Bl product is unlisted in the chart-but if you put it in, (assuming your program lets you do that) at a value of 13 Tm, I'll bet you will see a curve that is reasonably smotth. The smaller the Tm, the more irregular the response.
Your simulation shows something remarkable that I will explain later. Meanwhile, try inputting that 13 TM value in your various programs and see what happens.
The program where the enclosure worked well probably input a value of 13 Tm automatically, since it is not a spec Max speakers gives us.
Subwoofer simulator can be downloaded here:
http://www.geocities.com/f4ier/speaker.htm
The shape looks a little different, but if you check the markings, you see the variation is not any greater than the other programs'.
I included cone excursion for the two systems. Both for frequency response and cone excursion, vented is in white, bandpass is in yellow.
This system is run at 30 watts.
A few observations. First, it is quite useless to build any system that goes down to 20 Hz with this system when your cone excursion is only 4 mm. As you see here, the cone excursion required even at 30 watts is twice your stated cone excursion. And 102 dB is not really hearable at 20 or 25 Hz-you want more than that to be worth your while. Now you know why Shivas and other fine subs have linear excursions over 12 mm.
Does your various programs have a place to fill in the Bl product? The Bl product is unlisted in the chart-but if you put it in, (assuming your program lets you do that) at a value of 13 Tm, I'll bet you will see a curve that is reasonably smotth. The smaller the Tm, the more irregular the response.
Your simulation shows something remarkable that I will explain later. Meanwhile, try inputting that 13 TM value in your various programs and see what happens.
The program where the enclosure worked well probably input a value of 13 Tm automatically, since it is not a spec Max speakers gives us.
Ilianh said:hum.. seeing those excursion needs, i'd probably want to get something... more excursionable
Excursionable! LOL, I like it!
It should be pointed out that speakers come with extra excursion outside the linear range. Mechanical excursion-the actual range a speaker can move before damage occurs-is usually at least 1.5 to 2 times the linear excursion, (also written as Xmax). Unless Xmax specifies mechanical, it generally is assumed to mean linear.
That is why I chose 7 or 8 mm for the chart illustration instead of 4 mm. Your speaker can move past the linear ecursion, but compression and distortion begin to set in at that point.
Besides, the lower you go into the deep bass, the higher the SPL ahs to be to have an effect. 102 dB at 20 Hz might not be all that audible to a lot of people.
The configuration might be useful if the room has a mode that enhances bass between 20 Hz and 30 Hz-there it would be good.
Ilianh said:First day of new semester, second one. Out of six.. actualy im at school right now.. first day and I have 5 pages of homework in maths...
The only reason I asked was to find out if it was your first day of college so I could congratulate you. Now we know it isn't. But as long as I went down that road, I might as well find out: did you mean you have already finished six semesters or have six semesters ahead of you?
Ilianh said:I start college monday (around 40 hours classes / week)
Forty hours of classes? Do you have the same system up in Canada that they have in the USA? Here we generally aveage 15 hours a sememster-12 hours constitutes a full time student. It takes 120 hours total to graduate.
If you have the same system up there, then at the rate you're going, you will finish a four year degree program in a year and a half!!
Ahh yes, I miss those day-long class/lab sessions
I won't be experiencing them for a while. Good luck with your studies!kelticwizard, thanks for the kind words about SubSim, I appreciate it
I see you're beginning to like the program. SubSim is back under development, but finding permanent work is first in my to-do list, of course. So development is slow, but steady.cheers,
Isaac
f4ier said:kelticwizard, thanks for the kind words about SubSim, I appreciate it
cheers,
Isaac [/B]
I do mention the program frequently, because it has the most complete picture for any freeware program out there. Such matters as impedance phase, cone excursion, and so many other things all on one chart, all in front of you. Awesome.
I was slow to "take" to the program, but once I got the idea, it all fell into place. Realistically, it is not like WinISD where a 2 minute warmup is all that is necessary. But it isn't that long to learn either
The major thing that you have to get used to is the fact that when you "X" out of a dialog box that you just filled with parameters, the info is retained. In most programs, you need to click an box that says "OK" or else the information is lost. With this program, that is not necessary.
I will be checking into Crossover Simulator soon as well. Lots of questions there. Believe me, I'll give you a holler if I need help.
Good luck with your job search. If your contribution to this forum is any indication, the employer who hires you on will have done himself a great service indeed!
so, hum back to subject
The only way out of this is to actualy either have a large surface or a big x-max, I checked some 15's at 5mm xmax at a surplus store.
I guess a 10" with a very large xmax (expensive) would do as good as a 15" with relativly low xmax (cheap), but the 10"'s distortion will be greater.
and i get 2 of those for the price of one shiva, around 3 of those = to the price of 1 tempest with shipping and all
They are 85$ cdn each, no taxes, i'll ask and see if i can borrow one to measure it.
that will make me 2400 sqcm at 5 mm xmax
what do you guys think? the problem may be the size of that thing.. but.... the sound would be good
The only way out of this is to actualy either have a large surface or a big x-max, I checked some 15's at 5mm xmax at a surplus store.
I guess a 10" with a very large xmax (expensive) would do as good as a 15" with relativly low xmax (cheap), but the 10"'s distortion will be greater.
and i get 2 of those for the price of one shiva, around 3 of those = to the price of 1 tempest with shipping and all
They are 85$ cdn each, no taxes, i'll ask and see if i can borrow one to measure it.
that will make me 2400 sqcm at 5 mm xmax
what do you guys think? the problem may be the size of that thing.. but.... the sound would be good
The trouble with 15's is that they tend to have very large Vas values, making huge boxes necessary to get to the same F3 that smaller drivers can deliver in smaller boxes.
Still, measure it anyway, you never know what might be in store.
Inexpensive drivers from "off-brands" sometimes have Thiele-Small values that do not work out when placed in the box. Even good quality brands have variation from the stated specs, but at least have a tendency to deliver similar performance when placed in a box built for the stated specs. "Off-brands" frequently do not deliver when placed in a box built for stated specs.
But if they let you try it-hey, what have you got to lose? Every speaker company started out small and unknown, after all.
Still, measure it anyway, you never know what might be in store.
Inexpensive drivers from "off-brands" sometimes have Thiele-Small values that do not work out when placed in the box. Even good quality brands have variation from the stated specs, but at least have a tendency to deliver similar performance when placed in a box built for the stated specs. "Off-brands" frequently do not deliver when placed in a box built for stated specs.
But if they let you try it-hey, what have you got to lose? Every speaker company started out small and unknown, after all.
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