# Sdx15 sonotube design



## beolson

I bought an CSS SDX-15 a while back. I built a ported rectangular prism shaped box and was unhappy with it. I got rid of that and am now looking to build a Sonotube design with the help of a friend.

The issue I am having when looking at other threads is that they are all tuning at like 15hz. I will use this for movies but I really want to design it to have peak performance for music. From what I understand the max SPL will come at approximately 30hz(Not sure but I was told this). Anyways, I need a design that will work for both, Size is not a real issue but Sonotube is a must. I like that it can stand up tall without taking much floor space. 

I have seen on other threads that the best volume would be 400L which is fine.

What size should the sonotube be? 24" inside diameter? 20" ? How long does it need to be? 

For the Port, what size sonotube should be used? how long? and what can I use for flairing it? I can never find the right material to use for porting.

I understand that the MDF will be cut to fit the ID of the big Sonotube but what about the plate that sits on the outside of the sonotube? is there a standard such as 1" extra diameter or 2"?

How far away does the floor plate get mounted from the subwoofer? 

Any other things that you can think of to help the build would be greatly appreciated.

I have the EP2500 Behringer Amplifier and a Harman Kardon AVR 435 as the receiver. I use an optical input from my computer, usually. 

As a side note. I will be building 2 of these sonotube enclosures but I only plan on running 1 for at least a year or two before I get another SDX15 to put in the other one. Right now I'm in an apartment so 1 is more than my neighbors can take as they already complain about my 10" pre-built powered sub.:crying::hsd::crying:


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## Mike P.

> I built a ported rectangular prism shaped box and was unhappy with it.


​ 
Sealed or ported, and what size was it?


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## beolson

Lets put it this way, it was not designed using software or any intelligent design. It was ported and it was a cube that was about 27" cubed.

I really am curious what would be the best frequency to tune the box to for the music/movie combo.

Thanks for the quick reply.


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## Mike P.

I know where you want to go with the sub but in order for me to figure anything out I need to know where you were. I'll guess the 27" cube is an external measurement so the internal net volume would be about 8.5 cu.ft. What was the tuning frequency? Are you using any kind of Hi-Pass filter with the amp, like the Reckhorn B1 or B2 or the Elemental Designs EQ.2?


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## beolson

correct, that is the outside measurement. I didn't really tune it. I just built a big box with a slot port because I thought it looked better. I think I was getting a lot of vibration within the box. I don't remember the details. If I need a filter I can use one but I would like to plan the build without one and if it needs it at the end I can add one. Not sure if that is a good plan but that was what I was thinking. I know you like to tell people to use the HP filter so they won't blow up their sub but I have a pretty good ear for distortion and I tend to not turn the volume up to the point of distortion.

Let me know what you think. Thanks


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## Mike P.

This is 8.5 cu.ft. tuned to 20 hz compared to 12.5 cu.ft. tuned to 15 hz, both with 1000 watts input and no Hi-Pass filter. The larger cabinet gets much more low end extension at the expense of a few db in the 20 - 40 hz range, which is great for movies. I'm not sure what your expectations are for music though.


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## beolson

Well, I'm really looking for an opinion from someone who knows more about this than myself. I have been told that for music 30hz is the best frequency. This might not be true but it is what I've been told. Again I'm looking for the opinion of a more knowledgable person. So if you think tuning to 20hz is best I'll take your word for it. I understand the graphs but I don't have any way to compare the results to real life output.

HELP PLEASE!!

Thanks


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## Mike P.

Let's guess that your original sub was tuned to 20 hz, what about it were you unhappy with?


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## beolson

Well, it had decent low end bass but for my music it seemed like the volume output was much lower. If I played sign sweep type tracks it did great down in the 15-20ish Hz range but not as well at higher frequencies like 30 Hz. 

Thank you for being patient with my lack of knowledge and description. I appreciate all of the help.


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## Mike P.

I'm thinking there may have been a room interaction issue causing a null. How big is the room, is it open yo otherr areas or sealed off? Did you try different room placements? Did you have the sub in a corner?


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## beolson

Well, I was at college and did not have a lot of area in my room to place such a big box. It was along one of the walls toward the center of the room. The room was closed off until I opened the door which I did many times. It may have been bad construction that caused the issue as well. I did not tr ymoving the box to different areas because of the constraint of floorspace.

Out of curiosity ... Why so much focus on the previous box? It is gone with no possibility of getting it back. I am just looking for the best design from this point on. I would think we could start as if I never had another box and still come out with a good sonosub design.

Also, I need to design the box not really considering the room as I live in an apartment and will most likely move at least once every year or two until I find a house to buy.

Respectfully, beolson
:hsd::help::hsd:


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## beolson

AutoCAD drawing of previous design,

unfortunately measurements were not there


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## Mike P.

> Why so much focus on the previous box?


I just needed to understand what you had and why you were unhappy with it so I can make a recommendation for what you want. I'll do some figuring when I get off work.


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## Endesereth

Ive been thinking about making a CSS SDX15x2diver design tuned to 11hz in a 16ft3 box which would be awesome for movies. 
Since your looking for a movie/music design I would say 15ft3 with it tuned to 18hz with a highpass of 17hz 3rd order with 1000watts. This would give you some good extension and:hsd:
By the way do you have size constrictions? how much money you willing to spend on the amp?


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## Mike P.

12 cu.ft. tuned to 17 hz would give the most low end output and 30 hz output. You'll need a Hi-Pass filter at 15 hz to protect the sub from over excursion. The Reckhorn B1 from CSS would be the cheapest solution.


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## beolson

great, that sounds wonderful. Now how do I turn that 12 ft^3 17Hz tune into a reality with the sonotube design? I was thinking like 24" main tube with like 7" port tube. If that needs to change let me know but I need help with sizes and lengths of the parts. Thanks for all the help.


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## knobert

google sonusub.exe

it is a great program to help you with your dimensions and cut sheet. Also note, you can adjust your sizes and thickness of the endcaps and you can delete the bottom peiece entirely if you waant to, just make sure you put on legs tall enough for proper clearance


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## Mike P.

Here are the numbers you need for a 24" diameter tube. Shown is with a 8" diameter port, a much better choice for air speed control. The base plate legs should be 4" high.


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## beolson

Perfect, this is exactly what I was looking for. My next question will be about flaring the port. Do I buy something pre-made? Do I router some edge? if so what type of bit? and so on. 

Also can I add the HP filter later as long as I don't turn it up to high? I'm not broke but not rolling in dough right now either.

What type, how much, and where do I put any filler like polyfiber or whatever

Thanks again for all the help.


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## Mike P.

1. With a 8" diameter port in this design a 3/4" round over bit will be fine for the port ends. 

2. Yes, a HPF can be added at a later time.

3. No need for poly fiber in a ported design. 

4. You are required to take lots of pics of the build process and start a build thread.


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## beolson

lol, sounds good. I won't be starting it for a couple weeks but I will post lots of pictures. I did just get a new camera for xmas.

I'll write back when I am going to start the build. hopefully toward the middle of march.


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