details for videologic digitheatre dts sub driver please

[m1c]

hi all,
I'm completely new to this stuff. Just decided to construct my own sub using an old driver. As title really, I'm hoping I can make a small ht sub from it. But I cannot find any info about it. Any help would be appreciated even if it isn't possible. Thanks
Mic

[mikee55]

http://www.dvdtimes.co.uk/content.php?contentid=5530

Do you have an old driver and you wanna make a sub?
Or, am I barking up the wrong tree? Do you mean you have a driver from the above sub, and you like to make a sub with it?

Mike

[m1c]

hi Mike,
Thanks for the response. You are correct, I have the driver from the sub you link to. I was hoping to make a sub using the driver as I'm a bit strapped for cash. I need some guidance about getting started.
I hope this makes sense.
Mic

[dangus]

Properly, you need to know the Thiele-Small parameters for the driver if you want to design a box for it. That can be done using a computer with sound card and software like Speaker Workshop, or using basic electronics test equipment (signal generator, AC voltmeter, etc). There's also a gizmo called the Woofer Tester that makes it easier; it'd be best if you can find someone locally who's already set up to do that if this is over your head. But, it really isn't worth putting much effort into a driver like this; you'd be better off to just buy a new (or used) driver that is a known quantity.

But if you've got more time than money, you could start by making a box the same dimensions as the original sub: 350x245x400mm It was probably ported, so add a port around 20 to 30 mm diameter, of adjustable length, and see what length sounds right.

[mikee55]

This is simple, but good.
http://www.reaudio.com/speaker_box/LPort_Box_Calc.html

Then in detail
http://sound.westhost.com/tsp.htm

This member, helped me big time. Goes by the name, richie00boy
http://www.readresearch.co.uk/html/utilities.htm

reaudio's slot box was good for car use, loud but quality was a bit boomy. To measure T/S parameters of a driver, requires you to measure with accuracy. richie00boy's technique, checks whether you measured right or not.

http://www.thielesmall.com/
Although they supposed to have 4000 drivers listed, I didn't find mine. I ended up with no box http://home.comcast.net/~infinitelybaffled/index.html
http://ibsubwoofers.proboards51.com/index.cgi
You may need to log in, but interesting.

Mike

[m1c]

cheers for the advice.
if i was to make a box using the same dimensions as the original design (it was ported), what circuitry would i need?
sorry for being such a noob, only decided to do this a couple of days ago.
thanks again
mic

[mikee55]

Active is always the best way to go. You need a signal from your source. Simplest, is to come off of one of your speaker outputs on your main amp, step it down with a resistor divider, ( headphone circuit is good here).

http://sound.westhost.com/project100.htm

You then need a low pass filter and a beefy amp to drive your sub. If your main amp has a 'pre out', you can feed your lowpass filter(crossover) with that. Look at Rod's site, its all there.

http://sound.westhost.com/projects-3.htm
Looking at project 09
http://sound.westhost.com/project09.htm
just use the input and lowpass section, he gives a calculator to download, (Windows), which makes life easy. Choose a frequency where your main speakers roll off. ie if you have small bookshelves, maybe cross about 80hz, see how that sounds.

Mike

[m1c]

thank you so much for you advice. im going to read up on it.
thank you
mic

[mikee55]

If you get stuck, give us a shout.

Good Luck

Mike