The AV12 would probably work best in a vented alignment, since the Qts is.
The slight rise you referred to is a function of the Qts of the driver and the enclosure alignment. The larger the enclosure, the more efficient it becomes at allowing low bass to be produced with no roll-off, and the less vent length you need for tuning. The enclosure and the venting work in relationship with each other - if you alter one, you must also alter the other to compensate. The t/s parameters of the driver will tell you what vented alignment works best.
Try breathing through one nostril, then two, then your mouth - you get the idea. Multiple ports obviously reduce air speed, but they also simply allow more air to pass without restriction at a given pressure differential. but then I'll just be tripping over and cursing them nightly. Seriously though, what the hell am I supposed to do with 7-8 feet of leftover Sonotube? I thought about cutting it into a couple of pieces and letting my kids play with them. But after working on and finishing that pair of 8" 3-ways, I've got the bug to keep going. This is *supposed* to be a birthday present, and my birthday is still over a month away. I'll check back in for advice once I actually have the sonotube. that as you tune lower and lower beyond "flat", you get a nasty bump in response just before rolloff begins. I thought a couple of sources I read said. I have one question regarding "tuning" the box by changing the volume. I'd go multiple ports to decrease the airspeed, is that correct? I'd do 14" but that seems a little tight for a 12" driver. I don't want to go over 16", or I lose the advantage of small footprint. I've also written the formulas into Excel. it was one that was giving me a longer port for a smaller pipe if you use more than one. unless I'm supposed to cut the calculated length in half? What happens to length if you go to 2 ports that are smaller? Say, a single 4" to double 3"? I tried to do that calculation online, but kept getting a LONGER length for the double threes. especially if I can go no larger than 16".Įdit.I realize that as you go larger in diameter, a port has to get longer. that really was my first choice for construction (except for hiding the driver). but after just laying down the dough, and not having even seen the dang thing yet, I can't imagine hiding it! Also, honestly, this driver is pretty cool looking. or my two year old will figure out SOMETHING. for some reason I can't shake the feeling that I'm going to damage it SOMEHOW. I just can't seem to get comfy with a downward firing woofer. I won't do that, however, having to buy 12' lengths. That would give me a nice small footprint and plenty of internal volume. I'd like to use a 14" tube, 48" tall, if I could find it. It was suggested to me to use two tubes, like a 16" and 18", put the 16 inside the 18, and fill the space with expanding foam. You've got me thinking, again, about how easy a sonosub would be. and before that, get the dang thang home.
In general, the two pieces of software create very similar plots, and in fact close to identical at the bottom end where we're most concerned.I have as yet failed to find a retailer for a tube. I guess my point is that you're giving WinISD a bad rap about something that wouldn't be a concern to anyone except perhaps someone like yourself who wants accuracy across the board for testing. Certainly if the Le is a decent value, the crossover will overwhelm the response that is modified by the inductive reactance and so if it models a bit different above the crossover area it wouldn't be enough to make me change from the very nice flexibility of WinISD. not enough to worry about anyway for the average guy. The fact that it is standardized to 1KHz is because this is in the linear region of the driver and isn't a whole lot different at (for example) 100Hz.
The shape at the higher frequency is dictated by the series inductance Le. Fs is derived properly by WinISD from Mms and Cms, so both pieces of software as expected model the lower frequencies quite similar as evidenced by your graphs. The equivalent parallel inductance and resistance that concerns resonance is taken care of by Fs and Qts. Quite a few driver manufacturers don't even break out the series and parallel inductance values. Yeah, the Unibox model does look a little closer at the higher frequency where series inductance has an effect, but in the region from 10Hz to 60Hz, the two software models are almost identical. Click to expand.It's statements like this from someone very well respected in this field, that force me to comment, because you're giving WinISD a unnecessary bad rap.