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post #1 of 36 Old 03-15-2017, 07:39 AM - Thread Starter
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Changing from sealed to ported DIY design

Hi all,

I have been running a 10" CSS SDX10 driver with a BASH300 amp in a 12" sealed cube for a few months. Sounds pretty good to me, but when I model it on WinISD (first time modeling anything, learning as I go) it looks like I am losing a lot in the lower frequency range (as is expected with sealed vs ported...but I didn't think it would be that profound).

I built a sealed sub as my first DIY build for simplicity's sake. I would like to attempt to build a ported design to get the most bang for my buck out of my driver and amp though.

In WinISD, they suggest a ported design with the following specs:

65 L
Tuned to 24.5 Hz
Port size 4 x 4 inch x 29 inch long...this is the only thing that is concerning to me. That means the sub has to be 29" long....unless I put the port at the top of the sub? I was hoping I could make it a tall sub.

However, in the manufacturers PDF, they suggest a 43L box with a 3x17" flared port. Not sure why, because when I model that, it doesn't perform as well. Perhaps they are doing this just for the sake of space? Please let me know if you can think of any other possible reasons.

So I guess my other question is, once I decide on the enclosure based on the program, is there anything additional I need to do or consider other than building it, and installing the amp and driver? I know the amp has a 20 Hz HPF built in.

Looking forward to your responses.
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post #2 of 36 Old 03-15-2017, 08:43 AM
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The port only needs to be 29" in length. Instead of making it 24" in a straight line, consider putting in a slow bend elbow or two. This way you can still make your box whatever size you want. Here's a picture of one I did for my Sprite build which you can see here: Paul Carmody Sprite Build - Carbon Fiber and Blue LED's



You could also consider a slot port.
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post #3 of 36 Old 03-15-2017, 05:10 PM - Thread Starter
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The port only needs to be 29" in length. Instead of making it 24" in a straight line, consider putting in a slow bend elbow or two. This way you can still make your box whatever size you want. Here's a picture of one I did for my Sprite build which you can see here: Paul Carmody Sprite Build - Carbon Fiber and Blue LED's



You could also consider a slot port.
I like the idea for sure. So I guess it doesn't matter if it's bent eh? It just needs to be that certain length.

I actually wanted to do a slot port. How would that help though? The model is telling me I still need it 29" long.

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post #4 of 36 Old 03-15-2017, 05:47 PM
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I like the idea for sure. So I guess it doesn't matter if it's bent eh? It just needs to be that certain length.

I actually wanted to do a slot port. How would that help though? The model is telling me I still need it 29" long.
As long as you do slow bend you will be fine. You never want to do a sharp 90, as that can affect the flow of air. Then you buy your pipe, they have slow bends and sharp bends.

A slot port is sometimes easier for some people, especially to figure our total box volume. I posted a picture to show what I mean. With a slot port you can slot it out the front and then do a 90 along the back. Whatever space is left in the box, is your total box volume. So in your case 65L. So just to be clear, your box would be 65L plus whatever the port is.

Most people who do a slot port try to make it as close to the total width of the box. Or divide it by two and do two slot ports. That is completely up to your design.

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post #5 of 36 Old 03-15-2017, 05:53 PM
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Not sure if your T/S parameters are entered correctly, so you'll want to double check them. You need to make sure that the units are set the same as the manufacturers or you will be way off. Just click on the units in the driver editor to change them.

The Bash 300 is defaulted with a high-pass filter of 17.7Hz with a Q of 1. This can be modified by following the instructions here:
http://www.parts-express.com/pedocs/...tion-guide.pdf

So what you will want to do while modeling is add a high-pass filter (sub-type SOS) and enter the cutoff and Q as per the charts.

Increase the signal to the wattage your sub will play at. If you are going to play it balls out just put 300W. When you start playing around with the box, tuning frequency, vents, and HPF boost keep an eye on the cone excursion and port air velocity.
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post #6 of 36 Old 03-15-2017, 06:09 PM
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By my calculations with the SDX10 a 60.40L box tuned to 24.99hz would yield a very flat response. You could do 2 slot ports each 6" wide and total length of 22.13". So you would basically make the box 12"+1.5" (two sides of the box+0.75" (for a center brace down the middle of the two ports) = 14.25" wide. Then whatever depth and length you need to get to 60L.



*I did not factor in the Bash high pass filter.
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post #7 of 36 Old 03-16-2017, 04:21 PM - Thread Starter
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Originally Posted by Funkeye View Post
Not sure if your T/S parameters are entered correctly, so you'll want to double check them. You need to make sure that the units are set the same as the manufacturers or you will be way off. Just click on the units in the driver editor to change them.

The Bash 300 is defaulted with a high-pass filter of 17.7Hz with a Q of 1. This can be modified by following the instructions here:
http://www.parts-express.com/pedocs/...tion-guide.pdf

So what you will want to do while modeling is add a high-pass filter (sub-type SOS) and enter the cutoff and Q as per the charts.

Increase the signal to the wattage your sub will play at. If you are going to play it balls out just put 300W. When you start playing around with the box, tuning frequency, vents, and HPF boost keep an eye on the cone excursion and port air velocity.
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Originally Posted by Al Toid View Post
By my calculations with the SDX10 a 60.40L box tuned to 24.99hz would yield a very flat response. You could do 2 slot ports each 6" wide and total length of 22.13". So you would basically make the box 12"+1.5" (two sides of the box+0.75" (for a center brace down the middle of the two ports) = 14.25" wide. Then whatever depth and length you need to get to 60L.

*I did not factor in the Bash high pass filter.

As far as I can tell, I am inputing them correctly. I double checked the values and the units. See images below. However, I am still getting "driver fails integrity check" message. The only thing I changed that I wasn't sure about was the Znom from 6 to 4. In one of the tutorial links that someone sent me, it said that this should be done, as most sub drivers are either 4 or 2 ohms. Let me know if I messed up here. I did not put any dimensions in. Please see attached images.

I added a HPF as instructed, and put 1.0 as the Q and 17.7 Hz as the Fc. Question....why are these the values that I am choosing from these charts?

However, the cone excursion and air velocity are super high with this configuration.

When I add the 20 Hz butterworth HPF, everything looks good.

I am not sure which one is correct for the BASH amp? I always thought it was a 20 Hz HPF.
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post #8 of 36 Old 03-16-2017, 07:38 PM
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Originally Posted by Al Toid View Post
As long as you do slow bend you will be fine. You never want to do a sharp 90, as that can affect the flow of air. Then you buy your pipe, they have slow bends and sharp bends.

A slot port is sometimes easier for some people, especially to figure our total box volume. I posted a picture to show what I mean. With a slot port you can slot it out the front and then do a 90 along the back. Whatever space is left in the box, is your total box volume. So in your case 65L. So just to be clear, your box would be 65L plus whatever the port is.

Most people who do a slot port try to make it as close to the total width of the box. Or divide it by two and do two slot ports. That is completely up to your design.

Measure the port length down the center of the port, not the inside or outside.
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post #9 of 36 Old 03-16-2017, 10:14 PM
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Quote:
Originally Posted by Spectre55 View Post
As far as I can tell, I am inputing them correctly. I double checked the values and the units. See images below. However, I am still getting "driver fails integrity check" message. The only thing I changed that I wasn't sure about was the Znom from 6 to 4. In one of the tutorial links that someone sent me, it said that this should be done, as most sub drivers are either 4 or 2 ohms. Let me know if I messed up here. I did not put any dimensions in. Please see attached images.

I added a HPF as instructed, and put 1.0 as the Q and 17.7 Hz as the Fc. Question....why are these the values that I am choosing from these charts?
I made a YouTube video that shows how to input a driver correctly in WinISD. It'll fix your driver Integrity Check. You do have something a little off if it states that. It may not affect it much, but the video will help make sure you put them in correctly from here on out. Just clear out the data you have and start over fresh. I hope this helps:


As far as the port goes, right now you are making a square port that is 4.02 inches wide by 4.02 inches high x 28 inches long. That will be a hard port to make. It usually helps to make the port wider and shorter. Also, you can help with air velocity by adding more ports or making the port bigger (ie this will lengthen the port). Some subwoofers have to have very long ports in order to cut down on port noise.
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post #10 of 36 Old 03-17-2017, 11:45 AM
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I have extensive experience with this sub driver in both sealed and ported. I found the parameters dictated a ported that was shorter than what was actually needed. ie, If winisd said a tuning of 22hz and I build the box and port according to winisd, the tuning was actually 25hz. So in the end I added several more inches to get the tuning required. I cant remember specifically how much longer I had to make the port, but it is something to keep in mind. Err on the long side if you can. It does need quite a long port. Making the box bigger helps reduce the required port length. I really enjoy mine. Its in our living room for music and tv. Dual opposed ported sdx10 and I use a dayton SA1000 to power it. Its perfect for our needs in that room.

Ryan
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post #11 of 36 Old 03-18-2017, 03:51 PM - Thread Starter
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Originally Posted by Al Toid View Post
I made a YouTube video that shows how to input a driver correctly in WinISD. It'll fix your driver Integrity Check. You do have something a little off if it states that. It may not affect it much, but the video will help make sure you put them in correctly from here on out. Just clear out the data you have and start over fresh. I hope this helps:

https://www.youtube.com/watch?v=Ol7K...h1mTZK&index=1

As far as the port goes, right now you are making a square port that is 4.02 inches wide by 4.02 inches high x 28 inches long. That will be a hard port to make. It usually helps to make the port wider and shorter. Also, you can help with air velocity by adding more ports or making the port bigger (ie this will lengthen the port). Some subwoofers have to have very long ports in order to cut down on port noise.
Amazing!! I will check this out later tonight or tomorrow morning. Have been swamped with work and life the last couple of days.

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Originally Posted by tuxedocivic View Post
I have extensive experience with this sub driver in both sealed and ported. I found the parameters dictated a ported that was shorter than what was actually needed. ie, If winisd said a tuning of 22hz and I build the box and port according to winisd, the tuning was actually 25hz. So in the end I added several more inches to get the tuning required. I cant remember specifically how much longer I had to make the port, but it is something to keep in mind. Err on the long side if you can. It does need quite a long port. Making the box bigger helps reduce the required port length. I really enjoy mine. Its in our living room for music and tv. Dual opposed ported sdx10 and I use a dayton SA1000 to power it. Its perfect for our needs in that room.
That's interesting and good to know! What are your thoughts on this driver in a sealed vs ported setup? Another member of this site told me that they felt it sounded a lot better in a sealed design. Not sure why that would be. Perhaps the ported setup wasn't designed properly?
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post #12 of 36 Old 03-18-2017, 03:56 PM
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I like both for different reasons. Dual opposed sealed is in my HT and I really enjoy it. The ported does have more SPL and can shake your guts but it cuts off to early for my movie watching tastes. I like extension, even if low SPL.

Ryan
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post #13 of 36 Old 03-18-2017, 08:04 PM - Thread Starter
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I like both for different reasons. Dual opposed sealed is in my HT and I really enjoy it. The ported does have more SPL and can shake your guts but it cuts off to early for my movie watching tastes. I like extension, even if low SPL.
Fair enough! How low does your dual opposed seal extend? Same drivers? I wonder if I could buy another one and try that as well.
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post #14 of 36 Old 03-18-2017, 09:33 PM
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The sealed has a typical sealed roll off around 12db/oct from about 40hz and down, but in my room it doesnt roll off until about 15hz and below 10hz Im not getting much. I have it matched up with a minidsp pwr-ice250 and use the dsp to correct for the room. I really like having the dsp and amp all built into a plate amp. But its not a cheap amp for how little of power.

BTW, its an 18" cube and yes the drivers are also the sdx10. The ported gets to 22hz strong but then takes a dive quick below that.
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post #15 of 36 Old 03-20-2017, 06:41 PM - Thread Starter
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Originally Posted by Al Toid View Post
I made a YouTube video that shows how to input a driver correctly in WinISD. It'll fix your driver Integrity Check. You do have something a little off if it states that. It may not affect it much, but the video will help make sure you put them in correctly from here on out. Just clear out the data you have and start over fresh. I hope this helps:

https://www.youtube.com/watch?v=Ol7K...h1mTZK&index=1

As far as the port goes, right now you are making a square port that is 4.02 inches wide by 4.02 inches high x 28 inches long. That will be a hard port to make. It usually helps to make the port wider and shorter. Also, you can help with air velocity by adding more ports or making the port bigger (ie this will lengthen the port). Some subwoofers have to have very long ports in order to cut down on port noise.
So I watched and followed this (great video by the way, looking forward to watching the rest of the WinISD series), and I couldn't follow all of the steps because there is no Cms value for this driver. I still get an error message. I am not sure this is a big deal though? The graphs all seem to make sense to me. Thoughts?
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Originally Posted by Spectre55 View Post
So I watched and followed this (great video by the way, looking forward to watching the rest of the WinISD series), and I couldn't follow all of the steps because there is no Cms value for this driver. I still get an error message. I am not sure this is a big deal though? The graphs all seem to make sense to me. Thoughts?
The graphs will be off. This may be just a little, but could be a lot depending on what is wrong. If you are missing data like Cms, jsut skip it. WinISD will fill in the rest of the data. I have uploaded the data I have. The green is what I inputed, the blue was auto calculated by WinISD.

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The sealed has a typical sealed roll off around 12db/oct from about 40hz and down, but in my room it doesnt roll off until about 15hz and below 10hz Im not getting much. I have it matched up with a minidsp pwr-ice250 and use the dsp to correct for the room. I really like having the dsp and amp all built into a plate amp. But its not a cheap amp for how little of power.

BTW, its an 18" cube and yes the drivers are also the sdx10. The ported gets to 22hz strong but then takes a dive quick below that.

Thanks, sent you a PM
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Quote:
Originally Posted by Spectre55 View Post
So I watched and followed this (great video by the way, looking forward to watching the rest of the WinISD series), and I couldn't follow all of the steps because there is no Cms value for this driver. I still get an error message. I am not sure this is a big deal though? The graphs all seem to make sense to me. Thoughts?
The graphs will be off. This may be just a little, but could be a lot depending on what is wrong. If you are missing data like Cms, jsut skip it. WinISD will fill in the rest of the data. I have uploaded the data I have. The green is what I inputed, the blue was auto calculated by WinISD.

Thank you, will try again when I get home
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To throw another wrench in things. I came across this build online using two passive radiators. Again, this is completely new to me. But seems like it would be easier to build and to get right than a ported design. Especially if I'm hearing that this driver needs a longer port than winISD recommends.

http://www.diyaudio.com/forums/subwo...0-sub-kit.html

I don't see too many PR builds here. Any reason for that?
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Passive radiators add cost to a project without much benefit.

My comment wasnt meant to suggest something was wrong with porting this driver. Its very common for winisd to not give the correct result in the real world by a few hz. Just use winisd to tune lower than desired and build it like that, then you should get close to your desired result. Most people dont check their tuning so you dont hear much about it.

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post #21 of 36 Old 03-21-2017, 06:34 PM - Thread Starter
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The graphs will be off. This may be just a little, but could be a lot depending on what is wrong. If you are missing data like Cms, jsut skip it. WinISD will fill in the rest of the data. I have uploaded the data I have. The green is what I inputed, the blue was auto calculated by WinISD.
Thank you very much for providing. I inputed these and got a green light for integrity check. I checked, and the graphs are the same, but it's good to know that it is in properly now. The Vas in the spec sheet is 53L but WinISD calculates it as 49.6. I guess that's what it wasn't liking that I was putting in as a value. I also added the Xmax value in, and the integrity check is still fine.

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Passive radiators add cost to a project without much benefit.

My comment wasnt meant to suggest something was wrong with porting this driver. Its very common for winisd to not give the correct result in the real world by a few hz. Just use winisd to tune lower than desired and build it like that, then you should get close to your desired result. Most people dont check their tuning so you dont hear much about it.
Thank you for clarifying that.


So it seems after all of this I've pretty much come full circle back to wanting to design a vented setup. I have learned a lot in the process though!!


I am struggling now with the port design. @Al Toid , I tried inputing what you suggested, with the 6" wide ports, but not sure what their height should be? I also get too much cone excursion and air velocity when I play around with these. I am not going to be playing the sub at max levels, so I don't know if 300W would be the right power to put for signal. Maybe 200?

I also have a question about the HPF I am putting into the program. What is the difference between Butterworth and User SOS?

Many thanks again to everyone for your input.
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I added a HPF as instructed, and put 1.0 as the Q and 17.7 Hz as the Fc. Question....why are these the values that I am choosing from these charts?
Because the document states what the default resistor values are (30K and 120K). Read point 1 under "modifying bass boost". These values make the HPF 17.7Hz, Q=1. I figured it was a safe assumption that the resistors were default, but I suppose it is possible you bought a modified version.

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I also have a question about the HPF I am putting into the program. What is the difference between Butterworth and User SOS?
Many thanks again to everyone for your input.
The butterworth filter has a fixed Q depending on the order.

If you're comfortable changing the resistors it looks like R26=18K and R25=100K should work nice in a box ~60L tuned ~25Hz.
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post #23 of 36 Old 03-22-2017, 07:16 PM - Thread Starter
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Because the document states what the default resistor values are (30K and 120K). Read point 1 under "modifying bass boost". These values make the HPF 17.7Hz, Q=1. I figured it was a safe assumption that the resistors were default, but I suppose it is possible you bought a modified version.



The butterworth filter has a fixed Q depending on the order.

If you're comfortable changing the resistors it looks like R26=18K and R25=100K should work nice in a box ~60L tuned ~25Hz.
Thank you!

I am not comfortable changing the resistors. Too new to try something like that. Thank you for the suggestion though.

Seems that with the BASH factory setup, the driver hits Xmax around 19 Hz. Doesn't the filter stop the sub from playing that low anyways? I am just trying to figure out how to read that graph. That's with a 300W signal. I won't be playing my sub at full volume, but I am assuming during taxing movie scenes it may spike to that or more for short periods of time.

At that frequency, the SPL is -10 dB as well....

So is this something that I need to worry about? Or should this model work fine?

Thanks...
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post #24 of 36 Old 03-22-2017, 09:01 PM
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Originally Posted by Spectre55 View Post
I am struggling now with the port design. @Al Toid , I tried inputing what you suggested, with the 6" wide ports, but not sure what their height should be? I also get too much cone excursion and air velocity when I play around with these. I am not going to be playing the sub at max levels, so I don't know if 300W would be the right power to put for signal. Maybe 200?

I also have a question about the HPF I am putting into the program. What is the difference between Butterworth and User SOS?

Many thanks again to everyone for your input.
I'm glad you got it input correctly. Sometimes, it barely makes a difference and other times it makes a huge difference. I am glad you got it figured out!

As far as the slot port goes, you can put any size you want in there. I just figured 2 6 inch ports would be nice for the width of the cabinet that you would probably build. As far as the size of the ports go, the bigger the port = the longer the port needs to be to be tuned at the same frequency of a smaller port. This same principle holds true for the number of ports. IE 2 ports of equal size will end up being longer than 1 port of the same size (both being tuned to the same frequency. However, the trade off, is the larger ports and or the more ports will have less port noise. In WinISD this is displayed in the graph called rear port air velocity. You will want to keep messing with this until you get something that is an acceptable port length to air velocity.

Finally. to answer your question about the High Pass Once you add the user defined high pass in, it'll change all of your graphs, including cone excursion and transfer function magnitude. So what you see is what you get.
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post #25 of 36 Old Yesterday, 02:27 PM
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Quote:
Originally Posted by Spectre55 View Post
Thank you!

I am not comfortable changing the resistors. Too new to try something like that. Thank you for the suggestion though.

Seems that with the BASH factory setup, the driver hits Xmax around 19 Hz. Doesn't the filter stop the sub from playing that low anyways? I am just trying to figure out how to read that graph. That's with a 300W signal. I won't be playing my sub at full volume, but I am assuming during taxing movie scenes it may spike to that or more for short periods of time.

At that frequency, the SPL is -10 dB as well....

So is this something that I need to worry about? Or should this model work fine?

Thanks...
Your model is using a 2nd order butterworth filter @ 17.7Hz. Not quite factory....

Your SPL will roll off at the cutoff frequency, but the driver is still trying to hit that SPL which may push it beyond xmax.

Whatever you build, start at low volumes and gradually increase it until you hear the driver bottom out at those low frequencies, then immediately back off.

Last edited by Funkeye; Yesterday at 02:35 PM.
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post #26 of 36 Old Yesterday, 03:15 PM
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Originally Posted by tuxedocivic View Post
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My comment wasnt meant to suggest something was wrong with porting this driver. Its very common for winisd to not give the correct result in the real world by a few hz. Just use winisd to tune lower than desired and build it like that, then you should get close to your desired result. Most people dont check their tuning so you dont hear much about it.
WinISD was pretty much dead on for all the subs I've put together using slot ports. I kept hearing how it was off by like 20% before one of my builds, so I started with a short port that I was able to extend. Ended up right where WinISD said in the first place.
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post #27 of 36 Old Yesterday, 03:31 PM
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Originally Posted by notnyt View Post
WinISD was pretty much dead on for all the subs I've put together using slot ports. I kept hearing how it was off by like 20% before one of my builds, so I started with a short port that I was able to extend. Ended up right where WinISD said in the first place.
Id say you've been lucky. I probably worded it wrong. Winisd isnt ever wrong. Its just a glorified calculator. Unless the programming is wrong, it isnt. But the TS parameters can be off a bit. In my experience with this driver, a longer port was needed. The JBL 2226 Ive used have needed much shorter ports than expected. AndIve experienced other drivers that exhibit this behaviour. I suppose it could be that Im not taking driver displacement or bracing properly into account. Aftrr all, I am only talking about a few hz. Nothing like 20%!

Ryan
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post #28 of 36 Old Yesterday, 03:37 PM
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Originally Posted by tuxedocivic View Post
Id say you've been lucky. I probably worded it wrong. Winisd isnt ever wrong. Its just a glorified calculator. Unless the programming is wrong, it isnt. But the TS parameters can be off a bit. In my experience with this driver, a longer port was needed. The JBL 2226 Ive used have needed much shorter ports than expected. AndIve experienced other drivers that exhibit this behaviour. I suppose it could be that Im not taking driver displacement or bracing properly into account. Aftrr all, I am only talking about a few hz. Nothing like 20%!
After doing all the math and taking the side walls where the port ends into consideration (effective port length), bracing, driver displacement, etc, it's been within 0.5hz each time for me. That said, with bigger boxes, the difference in calculating something slightly wrong, say .1 cubic feet for driver displacement, or bracing, won't play as large of a roll. I know others have had issues with it, I just haven't run into them myself.
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most of the subs that i have seen measurements for come in under winisd tuning targets.
i can't recall any that have come in with a higher tuning.
also, at low tunings, the length of the port adjustment is large relative to what seems like a small change in tuning.
for a 9 cubic foot enclosure tuned to around 17hz, a single hz can be the difference in port length of 6" on a 42" port.
add to that the "adjustment" for how a slot port gets extended out past the end of the cab by 1/2 port height on both the inside and the out of the cab and a 3" tall port adds another 3" to effective length vs. measured length.
the slot port extension might be slightly higher for ports that fire along the floor vs. ports that fire in 'free air' (like not's build), but the difference is likely small. I'm not sure if anybody ever quantified the impact of a right angle bend, so that may be figuring in a hair as well.
6" + 3" = 9"; 9" difference in a port that is about 45" long is about 20%.
the takeway is that if the port length is off target by a couple inches one way or another, nobody is going to notice.
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post #30 of 36 Old Yesterday, 06:34 PM - Thread Starter
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Quote:
Originally Posted by Funkeye View Post
Your model is using a 2nd order butterworth filter @ 17.7Hz. Not quite factory....

Your SPL will roll off at the cutoff frequency, but the driver is still trying to hit that SPL which may push it beyond xmax.

Whatever you build, start at low volumes and gradually increase it until you hear the driver bottom out at those low frequencies, then immediately back off.
If I use "User SOS" filter and use 2nd order, 17.7 Hz and Q=1 (which I think is what I should be putting for the BASH) I get similar results.

Okay so this is my last shot at it or I'm just going to say f*** it and use the 43 L vented box with the 17" flared port as suggested in the driver PDF...

I select the driver....add User SOS filter with above specs....change signal to 300W.

Have to change the tuning from 24.99 Hz to 23 Hz to get back to a flat response with the transfer function magnitude graph.

Aaaaaaand I can't get the port air velocity and cone excursion to behave....changing the port dimensions, number, shape...changing box size....etc...ugh.

I give up
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