CSS SDX10 T-line design help

[stochastic]

Hey, I'm in the process of designing a box for my SDX10 and am leaning toward a t-line design. I don't have math cad as I run a linux system so if anyone could help me throw an ideal design together that would be wonderful. The ideal range for the sub in my system is ~20-100Hz (maybe slightly higher).

 

[bjorno]

..a box for my SDX10 and am leaning toward a t-line design..

http://www.diyaudio.com/forums/subw...s-sdx-10-ported-bash-300-a-3.html#post2935166

b

 

[stochastic]

Thanks, I knew this would be the place to ask for a starting point. If I was to do a mock-up box diagram for this driver would you mind giving it to the software to see the results?

 

[bjorno]

Thanks, I knew this would be the place to ask for a starting point. If I was to do a mock-up box diagram for this driver would you mind giving it to the software to see the results?

A mock-up box, if unseen, could be like to agree in advance of making a sweet dessert of a pig in a poke.. Lets first see what you got to offer...

b

 

[stochastic]

Okay, so don't laugh at me, but I'm trying to fit a t-line into the centre console of my car (i.e. rebuild it entirely as a speaker enclosure). I hear from all the car audio sound quality experts that moving the sub up front (instead of in the rear) vastly improves the feel and I'd love the concept of a t-line (provided there aren't too many acoustic drawbacks).

I've done some sketches and think I can make it work with a length around the 7ft mark - maybe more, but the cross sectional area and the speaker's rear chamber are both going to be fairly small. What acoustical disadvantage does this put me in? Would it be smarter to do a shorter t-line with bigger cross section to the pipe, just stuff it more to reduce sound speed?

 

[bjorno]

Okay, so don't laugh at me

No I'm + This is really a turnaround: Yet another disguised sub-woofer question I could have avoided if I in advance had known it was about Car audio. Why place a question in Sub Woofers when there is a Car audio forum?

..the concept of a t-line (provided there aren't too many acoustic drawbacks)..

You might tell us..BTW:Ever heard of cabin gain to start with? My previous link to the TL design using the SDX10 driver was IMO a miss-guiding.

You fooled everyone here by entering a sub-woofer driver of good quality for normal use in homes..Hence why I pointed at a TL for home use not relying on cabin gain that for sure is a key parameter when designing a sub for use in a car.

There is a forum for Car audio..

So let's maximally derate the possible performance of this IMO very good driver to be used in a Car:

Take a look at the submitted picture and note: the more you fold the given example the worst performance is expected as a function of increasing number of folds 3(more than 3 bends).

Stuffing should be placed evenly in 2/3 of the TL line counted from the closed end.

I've done some sketches and think I can make it work with a length around the 7ft mark - maybe more, but the cross sectional area and the speaker's rear chamber are both going to be fairly small.

Really,So you have decided on the engineering part how it would look like?
What's left for us to contribute?

What acoustical disadvantage does this put me in?

I guess anything that isn't in agreement with your wishful thinkings.

Would it be smarter to do a shorter t-line with bigger cross section to the pipe, just stuff it more to reduce sound speed?

More leading questions..Could sometimes be done until you hit diminishing returns but stuff it more to reduce the speed is a dead end and a delusion on how a TL is working.

b

 

[stochastic]

Hey Bjorno, I'm sorry if I posted in the wrong forum area, this is my second posting since joining this site (I realize post count isn't advertised here, but I'm a newbie to speaker design). Please feel free to flag me to the moderators and suggest this thread be moved to car audio, but I didn't realize the 'subwoofer' section was limited to home audio only. Is there also a pro-audio section as I've got a few questions about some JBL and Altec speakers I have in storage?

As for cabin gain, I was aware of it, but had honestly not realized it would influence the output of the speaker - the correlation hadn't crossed my mind. Furthermore, from what I know it's a very complex subject to factor in, but one I should be keeping in mind along the way.

I didn't want to throw all the details out in my first posting as I know almost all aspects of the system will effect the perfect subwoofer design choice but too much info in the first post deters people from reading/replying in most circumstances. I find an inquisitive approach to understanding the design functionality to be the best method. If you want to know more about my system, here's my build log: 2010 Hyundai Elantra Touring build - DIYMA.com - Scientific Car Audio - Truth in Sound Quality

Just to clarify, my sketches of possible T-Line boxes are merely starting points to see what would fit - this is one of my limiting factors. I'd really like to understand more about this type of box design on a basic level if possible (i.e. what compromises/factors are good and what ruin the design - such has bends, extra stuffing, directionality of the port, etc..) so that I can design a better box.

Can you elaborate on that design you've thrown together?

I do realize that this project has a number of acoustical faults, but I'm not attempting to create a mastering studio inside my car, I'm merely looking for an improvement over the current state. I realize the CSS SDX10 is a great driver, especially for the price, and that's why I bought it. I know that it would perform better in a different environment, but I have other subs for those environments. Thank you for all the feedback/info so far and hopefully you can teach me a thing or two about t-lines.

Sorry if my lack of info in previous threads pissed you off I'll gladly fill you in as I go, but I'm really just feeling out design options at this point. I plan on building this very professionally so it's just silly if I don't do the research ahead of time.

 

[bjorno]

Okay, so don't laugh at me, but I'm trying to fit a t-line into the centre console of my car (i.e. rebuild it entirely as a speaker enclosure). I hear from all the car audio sound quality experts that moving the sub up front (instead of in the rear) vastly improves the feel and I'd love the concept of a t-line (provided there aren't too many acoustic drawbacks).

I've done some sketches and think I can make it work with a length around the 7ft mark - maybe more, but the cross sectional area and the speaker's rear chamber are both going to be fairly small. What acoustical disadvantage does this put me in? Would it be smarter to do a shorter t-line with bigger cross section to the pipe, just stuff it more to reduce sound speed?

Hi,

Sorry for late posting...
Thank you for posting the link of your IMO very interesting Hi-Fi Car project using the Alpair10 as the main speakers...

No offense at all if it's the first time you've posted here at Subwoofers: You have probably already noticed that this forum seem to have a misnomer name as many of the threads covers High SPL/High Power Subs needing at least a sophisticated multi-band parametric EQ and/ or High order HP/LP filter FR slopes sometimes exceeding 24 dB/octave...and are not like the normal target for a sub= to be a reproducer with a flat or slightly sloping FR but rather barely cover the mathematical mid-bass octave.

BTW,Here's a picture(submitted) I've picked up here at DIYaudio showing the 'passive' gain in a couple of different car cabins (I made an overlay with my suggestion including the Alpair10) and a link to Tom Nousaine's CabinGain.pdf :

http://www.nousaine.com/pdfs/Cabin Gain.pdf

Have you worked out a practical design on paper yet?

b