# Dual CSS SDX10 Subs Query



## Westy (Sep 5, 2010)

Hello good people. I am in need of some advice and I believe I've found the right place! Plenty of knowledgeable people kicking around here. I'm going to throw all the relevant information out there so that someone can help me. So..........

I'm building some of Zaph's SB3 3" fullrange drivers for a stereo system at my desktop which will be crossed over using an active unit (the model of which is yet to be decided) at 150hz(ish) to dual subs run in stereo. 

Now I know this is a *hometheater *forum but with a wealth of knowledge in these products I'm hoping advice will still be forthcoming despite this system being designed for %100 music. You never know, with the cost of building these satalites I might be tempted to make up enough to use as a 5.2 system!

Anyway, onto the exciting stuff, I've recently purchased two SDX10" subs and they should be on their way soon :clap:. But.....I need some advice on constructing enclosures for them. I've dabbled in car audio before, I've got access to a good workshop and I'm comfortable constucting things with MDF so the actual construction isn't a problem. My real dilemna is whether to go ported or sealed. Could anyone give me a rundown of the basic pros/cons of each, keeping in mind that this will be used as a nearfield stereo system? I'll be running them in stereo and the relatively high x-over neccessitates seperate enclosures. 

Once I've established which *type* of box to go with I'll be able to narrow things down a bit more and ask some more specific questions. 

Thanks for sticking with me (if you've read this) I hope to get some responses soon :T

Oh, nice forum that you all have going here :wave: seems like a good place to be.

Cheers, Westy.


----------



## Mike P. (Apr 6, 2007)

Hi Westy, welcome to the Shack! Not knowing what kind of music you listen to, ported would have a fuller bottom end and is what I personally would do. Here's a comparison.


----------



## Westy (Sep 5, 2010)

Thanks for that mate. In most of the modelling I've seen, ported boxes seem to have a much better bass extension. Is there some sort of trade off involved here? What does a sealed box give that a ported can't?


----------



## mwmkravchenko (Jul 11, 2009)

> Is there some sort of trade off involved here? What does a sealed box give that a ported can't?
> http://www.hometheatershack.com/forums/32925-dual-css-sdx10-subs-query.html#ixzz0ynRB1Ksr ​


As Mikes great graph shows you. The driver you have chosen is designed for a vented enclosure. A driver that works well in a sealed box will have a much higher Qts closer to .7 or even higher. 

The drawback in sealed enclosures is that they will give you a little less low end. But other than that the sound is quite similar between a well designed vented or sealed enclosure.

Mark


----------



## Westy (Sep 5, 2010)

Ok so ported it is then  - 50l tuned to 25hz seems to be the consensus. A couple of questions then.....

I'm thinking a slot port would be easiest for me to construct and I like the aesthetic. winISD tells me that to use a circular vent it needs a diameter of 10.2cm and length of 69.55cm.

The cross section area of such a diameter is 81.71cm^2 - (5.1x5.1)x pi = 81.71

To use a slot port instead can I just ensure that the cross section area and length remain the same? Or is it more complicated than this?


----------



## Moonfly (Aug 1, 2008)

Once you have put all your parameters into WinISD, change the port form a tube to slot and it will automatically give you the figures, then you will have your answer :T


You can then alter the dims of the slot port (to make it square or more rectangular), and WinISD will adjust the length to suit in order to keep your tune. WinISD will do all the maths for you.


----------



## Westy (Sep 5, 2010)

Moonfly said:


> Once you have put all your parameters into WinISD, change the port form a tube to slot and it will automatically give you the figures, then you will have your answer :T
> 
> 
> You can then alter the dims of the slot port (to make it square or more rectangular), and WinISD will adjust the length to suit in order to keep your tune. WinISD will do all the maths for you.


Duh, Can't believe I didn't realise you could just click it and it would change :scratch:\

Ok next question, I understand that a roundover is preferable to prevent port noise, how do I incorporate this change in the port's shape into the measurements?

Edit: Also how do I go about checking the airspeed of the port?


----------



## Moonfly (Aug 1, 2008)

Check air speed by going to the 'rear port air velocity' graph. You can use a router to create the roundover in the port, you simply calculate half the round overs radius as as part of the port. So if you have say a 2 inch (radius) roundover for example, then it will add an inch to the port length, or remove an inch, which ever way you want to look at it.


----------



## Westy (Sep 5, 2010)

Moonfly said:


> Check air speed by going to the 'rear port air velocity' graph. You can use a router to create the roundover in the port, you simply calculate half the round overs radius as as part of the port. So if you have say a 2 inch (radius) roundover for example, then it will add an inch to the port length, or remove an inch, which ever way you want to look at it.


Thank you again :T I realised I was using the older version of winISD without the port air velocity function. 

Plenty for me to do now. Need to go away and sketch up an enclosure to make sure everything is going to fit/work out bracing and all that jazz. 

Cheers.


----------



## Moonfly (Aug 1, 2008)

Sounds cool. We can help with sketchup models too if you need help there. There are also some sketchup models available for downloads in the stickies, which might be of use. If you do a model, post it up for us and we can check that for you too if you wish, or just share it with the rest of the guys on the forums :T


----------



## Mike P. (Apr 6, 2007)

> I'm thinking a slot port would be easiest for me to construct and I like the aesthetic. winISD tells me that to use a circular vent it needs a diameter of 10.2cm and length of 69.55cm.
> 
> The cross section area of such a diameter is 81.71cm^2 - (5.1x5.1)x pi = 81.71


That would be 5.1 cm x 16 cm to have the same cross sectional area (81.6 cm). The port would be 71 cm long

The sub will handle 300 watts with a Hi-Pass filter at 18 hz, the Bash 300 is perfect for this setup. Port air speed is under 24 m/s. 

There's a link and tutorial on WinISD Pro here:

http://www.hometheatershack.com/for...wnload-detailed-guide-how-use-winisd-pro.html

And here's the project file for your SDX10. Save the file to the "Projects" folder in WinISD.


View attachment Westy SDX10.wpr

 

​
​


----------



## Westy (Sep 5, 2010)

Thanks heaps Mike. 

My project has taken a "slightly" different direction after looking at this site. 

http://www.subwoofer-builder.com/index.htm

Playing around with the flare-it calculator and working out the requirements so there is no chuffing or port compression has been interesting. 

I've managed to find my way around winsid now but thank you anyway for putting up the driver specs there though I found them somewhere else in the forum. 

I'll report back when I've finalised a design for these puppies :T

edit: oh these will be run active, looking at some behringer amps.


----------



## Mike P. (Apr 6, 2007)

If this for music only you will be good down to 20 hz without needing a hi pass filter.


----------

