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Discussion Starter #1 (Edited)
I bought a sdx15 a few months ago with the intention to build a sub for my home theatre that is currently under construction

the theatre has been delayed ( due to life getting in the way ) so it is now at almost finished electrical ... insulation coming tomorrow and drywall asap ... the theatre is part of a complete basement development including a 22 X 11 games room, a 13 X 10 gym/5th bedroom and a bathroom

My room dimensions for the Theatre are 23 X 14.5 X 8.5 ... Carada 136" diagonal 2.35:1 with Axiom M80/VP150/QS8 ... walls will be treated at first reflection points and soundproofed as much as possible with this design





My question is ... I have a space under the screen that is roughly 11 X 2 X 2 ... I originally bought the SDX15 to be one of 2 subs under the screen ... I thought of running one first and then deciding if I need ( make that WANT ) to add another sub at some point ... I plan to use either a EP2500 or similar to drive the sub(s) ... I would like bass that makes LFE come alive ! in the room

Is there a optimum LLT design that would fit under the screen either as a single sub or 2 subs ?

Thanks
 

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Re: CSS SDX15 EBS in 13cu. ft. ,15Hz tune.

My question is ... I have a space under the screen that is roughly 11 X 2 X 2 ... I originally bought the SDX15 to be one of 2 subs under the screen ... I thought of running one first and then deciding if I need ( make that WANT ) to add another sub at some point ... I plan to use either a EP2500 or similar to drive the sub(s) ... I would like bass that makes LFE come alive ! in the room

Is there a optimum LLT design that would fit under the screen either as a single sub or 2 subs ?

Thanks
Anywhere between 10.5-13ft works well with the SDX-15 in an EBS alignment. You have ~40ft? If you wanted, you could even go with three SDX's...but powering them would be a bit difficult.
 

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Discussion Starter #3
Re: CSS SDX15 EBS in 13cu. ft. ,15Hz tune.

Anywhere between 10.5-13ft works well with the SDX-15 in an EBS alignment. You have ~40ft? If you wanted, you could even go with three SDX's...but powering them would be a bit difficult.

A few questions then since I am a total noob

- is there a problem with making a enclosure larger ( say 20 cu ft each sub ) and doing 2 instead of 3 subs ?

- I have d/l both unibox and winsid and neither have the sdx15 sub in their database ... does anyone have the sub parameters that I can add to either sub software ?

- is there a preference between those 2 sub software programs - the subs will be rectangular in shape front firing/ported

- how much bracing is needed ( every foot or so ? )

- fiberglass insulation on inside ?

- can I just make a rectangular port instead of a circular one out of mdf ? ... is there any disadvantages in doing this ?

- how thick a mdf box should I make ? ... 3/4" ? ... 1.5" ?

here is a rough drawing of the proposed screenwall




Thanks for your help
 

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This is what's listed on their site:
Re: 3.6 (1.8 ohms per coil), Le:1.8, Fs: 19.2, Qms: 3.65, Qes: 0.44, Qts: 0.39, Vas: 218.44, Cms: 0.25, SD: 790, Xmax 30, BL: 16.5, Mms: 274.8, SPL: 87.3
 

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Discussion Starter #5
Thanks ... I saw that ... however not all the parameters that winisd is needing is provided so I get errors trying to input it ... thats why I was wondering if somebody had a copy of the parameters in the format that Winsid and unibox needs that I could just add to the driver database
 

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I had them but after buying the Tempest-X lost them.(the ones missing for WinISD)
You are going to have to go hunting through threads on it here and at avs.
 

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I modelled this driver in Unibox some months ago using the CSS supplied parameters and don't recall having any problems (other than lacking Re2/Le2 which most people happily ignore anyway). What's missing?
 

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Discussion Starter #8
If it works in unibox then that is what I will try ... I started with winisd as it did not look as intimidating a program as unibox and then got stuck on entering the parameters ... thanks for letting me know

any pointers on using unibox given that I will be modelling ~ 20 cu ft boxes ?
 

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Elite Shackster
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WinISD can be tricky. Read through this toutorial and it'll help with getting all of the numbers to line up and work properly.


- fiberglass insulation on inside ?

- can I just make a rectangular port instead of a circular one out of mdf ? ... is there any disadvantages in doing this ?

- how thick a mdf box should I make ? ... 3/4" ? ... 1.5" ?

here is a rough drawing of the proposed screenwall
I'm not at home so I can't model anything at the moment but I'll answer what I can.

Fiberglass - A-Okay :T You'll get differing opinions on this but I used it in mine and it's been just fine. Not to mention effective and cheap.

Rectangular ports are fine, though you may want to consider rounding the edges to prevent chuffing. WinISD has options for port sizing and shape.

3/4" MDF also just fine. More bracing is always a good thing but no need to get too carried away. A brace every foot or so would be enough. You made want to consider doubling up on the face you mount the drivers to. This dampens vibration and also gives the ability to recess the driver if you want. Good luck with the build, keep us posted!
 

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Although you have 20 cu.ft available for each SDX15, you will only need 13 cu.ft. net volume for each. This does not include the volume of the sub, port and bracing, which must be added to the net volume. With 13 cu.ft tuned to 15 hz, it will take 1000 watts input power and still be within Xmax if a 4th order subsonic filter is applied at 13hz. The port would need to be 8 inches diameter and 40.25 inches long to keep the air speed within acceptable limits.

SDX15.JPG


Here is a copy of the above modelling. Click on the file and it will open in WinISD Pro.

View attachment SDX15.zip

Here is the parameter file for the SDX15. Drag and drop the file into the Driver Database in WinISD Pro. Note: The "A.C." at the end of the file means the "Auto Calculate" feature in WinISD was used to create the file.

View attachment Creative Sound SDX15 (A.C.).zip
 

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Re: CSS SDX15 EBS in 13cu. ft. ,15Hz tune.

20 ft is too big for the SDX. If you want to use 20ft/driver, I'd look into the Malstrom-X, RL-p18, or even the Tempest-X.
 

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But wouldn't the 2 - 15's already be quite a bit in a 3000^3 room in a LLT configuration....
You don't have to make the boxes fit the space, how about just something smaller as suggested for the SDX's and fill the space in between the 2 boxes...

Nice theater BTW... I wish I had a dedicated space for my HT... Maybe someday...
 

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Discussion Starter #14
WOW ! ... thanks Mike & thx ... thanks fellas

Quick question ... what is a 4th order subsonic filter applied at 13hz ?


also given my 2' depth limitation but a 40.25" port ... should I port it straight to the side like towards the L & R speakers or can I put a 90 degree bend in the port and vent it forwards like my sketch ?


I roughed in 2 X Coax/RCA cables to the screen wall ... will that be OK to hook up the subs ?

also I have sen mention on here that a bfd is sometimes used with subs ... do you have to run rew first to determine the room modes as to whether you need a bfd or just more bass trapping ?

Thanks again
 

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A subsonic filter stops the lowest frequencies from reaching the sub, in your case it needs to block all frequencies lower than 13 hz. Some amps have a subsonic filter built in, the EP2500 does not. An example of an add on subsonic filter is the Reckhorn B1

http://www.reckhorn.com/index.php?ln=en&prod=b1

which can be bought from Creative Sound Solutions for $109.

http://creativesound.ca/details.php?model=B-1

Another example is the Elemental Designs eQ.2. $100 plus shipping.

http://www.edesignaudio.com/product_info.php?cPath=2_123&products_id=657

You can port out the sides as long as there is nothing blocking the exit. You can also use a 90 degree bend and vent out the front. A slot port along the bottom and part way up the back wall would give you the required length. If you use a slot port make sure you round over the edges to smooth the airflow.

Will you be using a EP2500 for each sub or one amp for both subs?

Running REW first is a must to determine what the BDF needs to do to smooth out the frequency response.

As for are the subs going to be enough, in a 23 X 14.5 X 8.5 room I think the subs will do just fine. You won't be lacking.
 

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Discussion Starter #17
Thanks Mike ... I had planned to use just one ep2500 ... can one filter do both subs or will I need one for each sub ?

since the ep2500 does not have a subsonic filter is there another amp in that price range that has one built in ?

Thanks
 

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One filter will do it. It connects between the receiver and the amp. I've read good reviews of the Reckhorn B1. I've also read that the ED eQ.2 has problems working with pro amps due to a voltage mismatch. The EP2500 is a good value for the money. Adding an adjustable subsonic filter gives you the ability to fine tune your setup to get the most out of it. I'm not aware of any pro amp with a SSF filter at the frequency you need.

Since the EP2500 will be feeding each sub 650 watts, the filter should be set to 12 hz to keep the sub within Xmax.
 

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Discussion Starter #19
You modeled the sdx @ 1000 watts and if the ep2500 is only pushing 650 watts per channel is it better to bridge a ep1500 for each sub instead ?

what would you recommend ?
 

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You certainly could. I can't see how to wire these subs effectively to get a 4 ohm load for a 2500 to run bridged. I don't think you'd notice a a whole lot of difference either way. In this case the extra 400 watts only equates to about 2 db, and that's continuous output. Peak output should be sufficient to 1000 watts. I wouldn't worry either way.
 
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