# Another CSS SDX10 Build



## cacophonix (Mar 26, 2007)

Hi,

I was looking for a small subwoofer for my living room that could blend well with the furniture and fit in-between the fireplace and the audio stand. Posted a thread a little while back, and based on the response, i decided on the SDX10 in a vented 1.5 cu ft cabinet. I'm not looking for the deepest extension but want good output. It'll be in a 16'x18' room with vaulted ceiling. I have taken the next week off, and am hoping to be done with the project by the end of next week. I have placed the order the sdx10 and bash amp; they should arrive by next Monday.

So before i start cutting MDF/Ply, i have a few questions:
- Is using 17" long, 3" port resulting in a box tuned at ~24hz the way to go? I saw a build by Owen where he increased the length of the port and lowered the tuning at the expense of output. I'm not sure if port noise will be a factor with lower tuning.
- Do you recommend stuffing the cabinet with polyfil or just line the inside with open cell foam? Do they really make a difference?
- I could not figure out how to calculate the port noise and excursion using winisd, as they change depending on the system input power. For box design purposes, do we go with 1.0w as the default input power?

Any tips are very welcome. Please keep in mind that 1.5 cuft is about the max i build while keeping peace at home.


----------



## dougc (Dec 19, 2009)

If that was the tuning for your box size with ok air speed, the box would need to be bigger most likely to lower tuning, and the vent length would change also. Use the rated watts for the sub. When I built my first ported subs, I was advised to use some sort of dampening material on the back wall of the sub to help with any internal resonances. I used household insulation because it was available, although messy. You can use a fine mesh or like material to cover the insulation to keep the glass dust out of your driver.


----------



## Mike P. (Apr 6, 2007)

The port air speed of a 3" port tuned to 24 hz in 1.5 cu.ft is simply too high at 40 m/s, there's no way around that. Since box size is a priority I would suggest a SDX12 in 1 cu.ft. powered by a iNuke 1000. That will give you the "good output" you're looking for in your room size.


----------



## cacophonix (Mar 26, 2007)

Ouch ... but unfortunately, i've already bought the SDX10 and the BASH amp. They are on their way to me via UPS. What should the port length/diameter be to reduce the port noise? Will having a slot port help?


----------



## Mike P. (Apr 6, 2007)

A slot port will do it to increase the port area and lower the air speed, I'll need the internal cabinet width to figure it out.


----------



## cacophonix (Mar 26, 2007)

Mike,

The cabinet dimensions i was looking at is about 11.5"(w) x 14.5"(h) x 16.5"(d) [All internal dimensions].


----------



## Mike P. (Apr 6, 2007)

Did you go with the stock Bash 300 (17.7 hz HPF) or did you have the hi-pass filter modified to 20.4 hz?


----------



## cacophonix (Mar 26, 2007)

No, i ordered the amp from PE directly and the driver from meniscus. So the amp is stock.


----------



## Mike P. (Apr 6, 2007)

A slot port 14.5" W x .75" H x 31" L will work. 

The port will be L shaped, the intake, exit, and corner will have to rounded over.

Maximum air speed will be just under 26 m/s peak. 

Using 3/4" material for the port it will displace .4 cu.ft. so you need to increase the depth and/or height to get a total internal volume of 2 cu.ft.


----------



## cacophonix (Mar 26, 2007)

Thanks Mike.
Unfortunately, i cannot go beyond the 13" external width. So can i increase the height or length instead?


----------



## Mike P. (Apr 6, 2007)

My mistake on the width, I'll redo it.


----------



## Mike P. (Apr 6, 2007)

A slot port 11.5" W x 1" H x 33" L will work.

Maximum air speed will be just over 24 m/s peak. 

Using 3/4" material for the port it will displace .4 cu.ft. so you need to increase the depth and/or height to get a total internal volume of 2 cu.ft.





​


----------



## cacophonix (Mar 26, 2007)

Hmm ... wonder how i can fit a 33" slot in a box that is going to be about 18" deep. any way we can reduce the length by increasing the height? If not, any other 10" driver you can recommend that will be a better fit in a 1.5cu ft or less box?
Also, just curious, why are we looking at the volume displaced by the slot, when we don't seem to be doing so for the port? I mean, 17" long 3" port also takes up quite a bit of space ...


----------



## Mike P. (Apr 6, 2007)

> any way we can reduce the length by increasing the height?


No, the port width and height determine the port area for air speed control, the length of the port determines the tuning frequency in relation to the cabinet volume. Increasing the port area increases the length for the same tuning frequency. 11.5" W x 1" H x 33" L is as small as you can go with this sub design.


​
All port volume whether a plastic tube or a slot port needs to be added to the total internal volume. The sub needs to "see" 1.5 cu.ft., the port, driver and any bracing are not part of that.

The port length isn't a problem, determine what the internal dimensions will be for a 2 cu.ft. box and use a L shape (across the bottom and up the back wall) or a U shape across the bottom, up the back wall, and across the top) to get a 33'' long port. 

The front baffle accounts for .75" of the port and the port length is measured through the center of the port.

Let me know what dimensions you come up with for the box and we'll figure the port out.

​


----------



## cacophonix (Mar 26, 2007)

Thanks, Mike!

I measured the area again, and the box will have to be 13"wx17"hx19"d

I'll start cutting plywood come monday ... and am hoping to nail the design by then


----------



## cacophonix (Mar 26, 2007)

Hi Mike,

Ignore my prev post.

13x19x20 will be my external dimensions. Add 2 braces and 1.5" baffle, the total volume should be pretty close to 2 cu ft. The material will be .75" MDF, and i'm thinking of gluing 1/4 hardi-backer on the sides/top to make the cabinet non-resonant.
So i'm guessing we need a U shaped port, with the port exit being located on the rear somewhere in the middle. I can mount the amp near the top of the rear baffle, and the woofer can be mounted at the top so that there is some space for a U shaped slot.
Will this be okay?


----------



## Mike P. (Apr 6, 2007)

That will work fine.


----------



## cacophonix (Mar 26, 2007)

I'm having trouble accommodating the full length of the slot. Can I fold the slot at the bottom of the cabinet such that the mouth is at the bottom of the front/rear baffle?


----------



## Mike P. (Apr 6, 2007)

You lost me. Can you post a drawing?


----------



## cacophonix (Mar 26, 2007)

Sorry for not being clear, Mike. Hopefully the image will explain better. Here's what i'm thinking of doing:


----------



## Mike P. (Apr 6, 2007)

That 180 turn could be a problem, I would suggest going up the back wall part way (to the bottom of the amp) and then coming out again. A U shape would be better for this setup due to the port air speed. All inside and out side corners of the port need to be rounded over, that is essential.

One other advantage of the U shape is it will act as bracing for the sidewalls of the cabinet.


----------

