I watched 123toid's videos on winISD so I thought I'd give it a try. I added my woofer (10" RS270P-8A). I picked vented and cheby-chev (however you say it).
The program came up with a tuning frequency of 25Hz with a box volume of 1.65 CuFt. I'm clueless as to what I'm looking for on the graph. I noticed the more I increase box volume the further the line goes to the Left before it starts to roll down hill. If the box (volume) gets to big the line on the graph forms a hump.
So I'm assuming I want the line on the graph to be as flat as possible,with no humps? I made the volume 2CuFt and tuning frequency 28Hz. (See the the included picture). What is this graph telling me? Its not a whole lot different than the graph at 1.65CuFt at 25Hz. Do I also want my tuning frequency to not be lower than -3db on the graph?
- Right now the graph is just showing you what your f3 is. As far as whether you want it flat or not, that really depends on what you're going for. Knowing the background of what you're trying to do, you will want it flat. However there might be a time where someone's trying to make like a boombox, where they want a big jump in bass. What you're going to want to do from here though is to go to the signal tab and put a decent amount of simulated power through that woofer. once you've done that, then change your graph from transfer function magnitude to cone excursion. then when you start manipulating those numbers, you're going to see a difference in your cone excursion. You don't want it to go above that red line. You can also take a look at Max spl. Let me know if that helps. If not, I'll help walk you through it.
Thanks for the help. I now get what I'm looking for. The only problem is I cant get the "cone excursion" graph to do anything. My winISD looks sligtly different than yours on youtube with my "tabs" in different spots. So I clicked on the "signal" tab at which I typed "100" W in the System Input Power box. I then went to the transfer functions and selected "Cone Excursion". (I made sure NOT to pick "PR Cone Excursion"). It gives me a graph with a flat red line at around 7 (whatever that number represents, xmax perhaps?). Then under that line it shows a black line with some very slight rolls/bumps. The highest the black line gets to the red line is 4. I changed box volume (from 1 CuFt to even 5 CuFt) and tuning (5Hz to 30 Hz) and the black line never changes. I also clicked on the word "Generate" which made crazy noises through my headphones lol. But still, the graph didn't move at all. Theres also a box next to the word Generate in Hz. I played with that too. My guess is I'm mot activating something.
Make sure you are looking at cone excursion and not cone excursion (pr). If you are looking at the right graph, then it means you did not put in all the data. Most likely xmax.
You were right. I somehow forgot to enter in the xmax value. The cone excursion chart works fine now.
First time building and on this forum!
Got another WinISD question: I'm comparing a passive radiator and ported design, and I'm coming up with a need for 2x12" PR's for a set up of 2x4" woofers (and a tweeter). This doesn't make sense to me, as the "rule of thumb" is 2x speaker diameter. If so, I should only need one 8" PR, but this yields bad results.
Any ideas what could be wrong, if anything? Or are these graphs about right?
So a little confusion there. The typical rule of thumb is two times the volume displacement. To find the volume displacement, you take your xmax of your driver and multiple is by you surface diameter. SO if we take this subwoofer here your volume displacement would be (8.8xmax X 213.8sd) = 1881.44. Now double this to see what passive radiators will work. In order to have one that will work you take 1881.44*2 = 3762.88. So if you wanted to use this passive radiator, it's volume displacement is (11xamx X 211.2sd) = 2,323.2. You would need two of those passive radiators to cover that amount of volume displacement of one of the subwoofers.
Now it is important to understand what this means. This only means that these will most likely work well as far as xmax goes with the passive radiators. This does not mean it will tune well or work for the desired response you want.
For the TCP 115-4's volume displacement is 201.2. SO you will need something that will cover at least 402.2. The 8" passive radiator linked above would easily do that. Two of these much small passive radiators would work. You may be able to get away with one..you'd' have to trial and error it in winisd. Just keep in mind, winISD for passive radiators is somewhat broken. It will not spit out the right volume. You need to manually change your box volume.
Awesome, thanks for the explanation! I'll keep working on it in WinISD today.