4th order adjustable port help

[alaskanzx5]

Well that helps me a lot thank you.

[4bannger]

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.

Okay well I have a toyota sequoia suv. Thanks for taking so much time to help. I don't have my computer on hand. So if you would like or maybe you wanna kill some time. Could you model a 4th order wall with 4 cuft sealed and 7 cuft ported. I'm not sure what my the best option for tuning would be. I currently have my 4th order tuned at 40hz but you you had a better suggestion that would be great.

[kirill007]

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.

Why would you think he needs more low end? Cabin gain will take care of that in his SUV, except if he wants a exagerated low end.

And this was a example, not for his situation.

I lost the driver since my laptop had a few problems.

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.

Okay well I have a toyota sequoia suv. Thanks for taking so much time to help. I don't have my computer on hand. So if you would like or maybe you wanna kill some time. Could you model a 4th order wall with 4 cuft sealed and 7 cuft ported. I'm not sure what my the best option for tuning would be. I currently have my 4th order tuned at 40hz but you you had a better suggestion that would be great.

I'm trying to tell you that a 4th order won't give you satisfactory results over a ported box in your situation.

As you can see on the graph, the peak of the ported box is 128dB and the one on the 4th order bandpass is only at 124dB, which is 4dB lower which is noticeable and the average (useable) SPL is higher.

Bandpass only has disadvantages in your case (SUV), quieter, not as good frequency response, more volume is needed, you don't notice stress on the subwoofer as easy,...

EDIT: what is the issue with your 4th order bandpass at the moment?

[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.

Why would you think he needs more low end? Cabin gain will take care of that in his SUV, except if he wants a exagerated low end.

And this was a example, not for his situation.

I lost the driver since my laptop had a few problems.

Cabin gain will neither keep excursion under control below tuning, nor flatten out the peak at 38Hz. Moreover, low notes are a lot more difficult to achieve than high ones and this quote from the OP leads me to believe that he does indeed want improved low end response:

"Would like to move more air and hit the lows better".

[kirill007]

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.

Why would you think he needs more low end? Cabin gain will take care of that in his SUV, except if he wants a exagerated low end.

And this was a example, not for his situation.

I lost the driver since my laptop had a few problems.

Cabin gain will neither keep excursion under control below tuning, nor flatten out the peak at 38Hz. Moreover, low notes are a lot more difficult to achieve than high ones and this quote from the OP leads me to believe that he does indeed want improved low end response:

"Would like to move more air and hit the lows better".

Offcourse it won't keep excursion under control but the low end will be "boosted", which means if you tune to a flat response in Winisd, you'll get a heavily exaggerated low end.

If that's what he wants he can just tune 6Hz lower, eventhough I wouldn't recommend it unless he only plays chopped and screwed music and other bass that is only below 40Hz, everything above that will be quite a big compromise.

And as I said before this is just a example, not a box specifically designed for him, but it would probably work good enough for him.

Moving more air and hitting the lows better isn't a good description of a goal.

[bbeljefe]

Offcourse it won't keep excursion under control but the low end will be "boosted", which means if you tune to a flat response in Winisd, you'll get a heavily exaggerated low end.

If that's what he wants he can just tune 6Hz lower, eventhough I wouldn't recommend it unless he only plays chopped and screwed music and other bass that is only below 40Hz, everything above that will be quite a big compromise.

And as I said before this is just a example, not a box specifically designed for him, but it would probably work good enough for him.

Moving more air and hitting the lows better isn't a good description of a goal.

No, when you roll off at 28Hz and get acoustical gain below that, you get a wider, more flat response curve. A built in peak at 38Hz isn't going to improve low end response, it's going to improve response in the 30s.

And what's wrong with the man's explanation of what he wants? He said he wanted better lows and more air movement. Unless he is confused about what a low note is, the description seems pretty simple and well articulated to me.

[4bannger]

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.

Why would you think he needs more low end? Cabin gain will take care of that in his SUV, except if he wants a exagerated low end.

And this was a example, not for his situation.

I lost the driver since my laptop had a few problems.

Cabin gain will neither keep excursion under control below tuning, nor flatten out the peak at 38Hz. Moreover, low notes are a lot more difficult to achieve than high ones and this quote from the OP leads me to believe that he does indeed want improved low end response:

"Would like to move more air and hit the lows better".

Okay maybe it was me that is starting the confusion. I will restate my goal and maybe this will make more since. I want to build the best box for all around spl. My goal is to get these subs as loud as I can. I would like to tune the box to something that will do good and be loud on the different frequencies. And I would also like to make the box into a wall if at all possible. I've never don't a walled build and would like the experience.

There was nothing really "wrong" with my current 4th order box. I just wanted to know if it could be better or louder. To the ear o meter it's pretty loud but I'm sure with a better box it could be better and louder.

To explain what I currently have just incase if everyone missed it. For sub amp I'm running a

Ta1.3000d and have 2 alpine type r 15's dual 2 being wired at .5

Maybe you guys who are much more experienced than me can give me some good ideas as far as airspace and tuning. I've built ported boxes I just don't know how to build a box geared about getting as loud as possible and still being musical.

[4bannger]

One more thing and sorry for posting twice (editing the post sent me to a weird message box thing) how are 4th orders not good for SUVs from what I have seen most walled suvs are 4th order boxes and they are hitting pretty high numbers. I guess the difference is those boxes they might not be so "musical" and only hit good number on a termlab at certain frequencies.

[kirill007]

Offcourse it won't keep excursion under control but the low end will be "boosted", which means if you tune to a flat response in Winisd, you'll get a heavily exaggerated low end.

If that's what he wants he can just tune 6Hz lower, eventhough I wouldn't recommend it unless he only plays chopped and screwed music and other bass that is only below 40Hz, everything above that will be quite a big compromise.

And as I said before this is just a example, not a box specifically designed for him, but it would probably work good enough for him.

Moving more air and hitting the lows better isn't a good description of a goal.

No, when you roll off at 28Hz and get acoustical gain below that, you get a wider, more flat response curve. A built in peak at 38Hz isn't going to improve low end response, it's going to improve response in the 30s.

And what's wrong with the man's explanation of what he wants? He said he wanted better lows and more air movement. Unless he is confused about what a low note is, the description seems pretty simple and well articulated to me.

You say the same thing as I do, not only do you gain below 28Hz, you also gain above 28Hz.

As I said 3 times already this was just a example, not for him. There are scenario's where a peak at 38Hz in Winisd will result in a flat response once in the car.

[kirill007]

One more thing and sorry for posting twice (editing the post sent me to a weird message box thing) how are 4th orders not good for SUVs from what I have seen most walled suvs are 4th order boxes and they are hitting pretty high numbers. I guess the difference is those boxes they might not be so "musical" and only hit good number on a termlab at certain frequencies.

Usually those 4th orders are with large numbers of drivers and lots of power to make up for the lack of a good enclosure. (or they aren't "musical" even though that is very different between people)

If you want to experiment with 4th orders, then do it, if you want to build something really loud and sound good at the same time ported box is the (easier) way to go.

I don't really design enclosures for other people since I need the car in front of me to do measurements.

I can help you design yours though.

Aim for a good amount of port area,100- 120sq inches of port area.

Model the enclosure for getting a decent peak but not too big (5-6dB) compared to the frequencies you would like to get, you'll probably have to tune around 30Hz if you want to go really low, but you might lose some top end.

What are the specifications on your current box?