4th order adjustable port help

[kirill007]

http://redspade-audio.blogspot.be/2010/06/winisd-entering-new-driver-data.html

[4bannger]

In the help function they explain properly how to input a new driver, there is a certain order to it and you'll have to let the software calculate a few values for you.

Never pick another subwoofer if you aren't going to use that one, not even one that might be close because it will be different as you probably already knew.

I've gotten that far into it but like the type r for example non of the site I found no the alpine site list all the stats I need to put it. I know the program will calculate some of the missing info but with the info that's on the site won't even get me that far.

My idea was to make a 10 cuft gross box before all displacement from bracing and subs. And make like 6 maybe more bolts on adjustable ports make them for 29hz 32hz 35hz and 40hz and make 2 for each tuning and test large port area and small port area. Large port area like 15spin per cuft and for small like 10 sqin per foot

[4bannger]

In the help function they explain properly how to input a new driver, there is a certain order to it and you'll have to let the software calculate a few values for you.

Never pick another subwoofer if you aren't going to use that one, not even one that might be close because it will be different as you probably already knew.

I've gotten that far into it but like the type r for example non of the site I found no the alpine site list all the stats I need to put it. I know the program will calculate some of the missing info but with the info that's on the site won't even get me that far.

My idea was to make a 10 cuft gross box before all displacement from bracing and subs. And make like 6 maybe more bolts on adjustable ports make them for 29hz 32hz 35hz and 40hz and make 2 for each tuning and test large port area and small port area. Large port area like 15spin per cuft and for small like 10 sqin per foot

[4bannger]

Okay so on a side note I'm making a new box. False wall 4th order the sealed side is 4.5cuft before displacement. And the ported is 7.5 after port without factoring in bracing. Going to adjustable port. Going to hear how it sounds and see if I like it and mess with the tuning a little. If I like it I'll make the false front and back that go from the floor to the ceiling. Or wait till I get some sundown x15's

[kirill007]

This is how your box's (4th order tuned to 38Hz, because the 29Hz looked even more redicioulous) SPL graph looks like:

EDIT:

This is how a ported box tuned to 34Hz 9cu ft of internal air space and 140sq inches of port looks like:

[4bannger]

This is how your box's (4th order tuned to 38Hz, because the 29Hz looked even more redicioulous) SPL graph looks like:

EDIT:

This is how a ported box tuned to 34Hz 9cu ft of internal air space and 140sq inches of port looks like:

Is that good or bad. Please bare with me I'ma bit of a newb

[kirill007]

No problem, I can explain what you are seeing, but to properly interpret the graph I need to know what vehicle you have since that will affect frequency response in the lower area.

But as you see in the top one, you have a peak at around 30Hz and everything above that will drop quite quickly, at 50Hz you have already dropped 7dB in comparison to the peak at 30Hz, and at 60Hz you'll be left with almost nothing. That isn't a huge problem if you had great midbass in the front stage, but that's quite hard to achieve.

So to have some bass above 60Hz, you'll have to make that up by letting your subwoofer play those frequencies up to about 80Hz, I don't recommend any higher if you care about staging, if you don't then up to 100-120Hz will be fine but then you'll have to watch out for the subwoofer overheating if you are overpowering it.

And if you look at the ported box you can see that the usuable frequency range will be about 30-90Hz, the peak is 6dB higher then the 30 or 90Hz tone which seems quite a lot but usually it's nothing too bad.

Because of car acoustics you'll have a fatter low end, which means you might even play down to 28Hz with authority.

Not knowing what kind of car you have means that this enclosure is just a example.

[bbeljefe]

OP, here is a link to the owner's manual for the Type R 15. It has all of the pertinent TS numbers for the driver.

Kirill007 - Since you already have the driver in your database and if you don't mind, try modeling it with a tuning of 25Hz. That's a low EBP sub with a low Fs so keeping the volume large like you have it and lowering tuning should improve low end response... although it may result in a nasty dip above tuning. But there's only one way to find out.

Another thing you may want to consider, OP, is a quarter wave transmission line. It will be a monster big box but given the dimensions of your 4th order, you seem not to be concerned with space and a t-line will give you the best low end extension while still maintaining a flat response all the way to the midbass region.

Here's a very good write up on t-lines (on this site) and there are also a number of them on the interwebz. To give the drivers some acoustical suspension and help reduce overall box volume, I would reduce the line area by about 20% and tune it at Fs. If you're interested in chest compressing, house shaking low end response, you won't build a better box.

[alaskanzx5]

Question about the winisd graphs.

I somewhat understand them but what I don't understand is how to interpret at what freq range it will play its best. Ice heard that its anything above 0db and I've heard that it can go down to -5db.

askng because 1 I would like some input on that and 2 I'm sure op would.

[bbeljefe]

When looking at a response graph everything at 0dB is flat, meaning that it won't be boosted or attenuated. In the graphs above, everything at ~120dB should be flat and then, the rest is obvious.

The point at which a loudspeaker's response is below usable levels is called F3 or -3dB, which means it is 3 decibels below flat. That translates to about half the perceived volume level of flat response. The rate at which response falls is called the slope and it is measured per octave. In the ported graph above, the slope is ~24dB per octave, meaning that the response falls by 24dB from the point it falls below flat (28Hz) until the next lower octave, which is half that frequency (14Hz).

Also notice that response falls at ~24dB per octave from the tuning frequency. That's typical of a box with ample volume. When the box is too small, the slope gets worse, sometimes to the point that it looks like a perfectly vertical line.