I've just picked up a pair of 8" sundown subs from the guys at Psychoacoustics and I need a box design for them.

I've heard good things about TL's and their ability to get low so I'd like to give it a try because I listen to a lot of rap and stuff that drops fairly deep...

does anyone have a design kicking around or would you be willing to design a new one for me?

 

pics or didnt hapen

 

Do you have the TS parameters for the subs? How much space are you willing to give up? TL's are large. Do you want subs together or separate?

 

What tunning are you looking for? TL's are tricky to design, but I can calculate the vent length if you need. Do you know if you want a tappered design or straight?

 

There's better loading with a tappered design... if designed right should need little to no fill...

I've got a crap load of reading material from Martin J. King on TL's if you want it Jordy. It's alot to grasp, but you can toy around with it. Everythings there.

Is this for home or in car?

 

lol... i've read a lot about them, but I just haven't got the patience to figure out how to design a setup

I don't have the TS's... let me see if Sundown still has them available.

 

Here we go....

T/S S4 **:

RMS: 200
Re = 3.37 ohms (4 ohm nominal)
Fs = 34.9 hz
Qes = 0.5323
Qms = 6.93
Qts = 0.4943
Vas = 7.6 L
BL = 13.3 N/A
Mms = 127.7 grams
Cms = 162 um/N
Xmax = 12mm one-way linear (70% BL method)

 

What were you planning for LPF frequency and slope? Ballpark.

 

LPF and slope? .. not sure... I'd have to check out the specs of the amp I'm using. It's an MTX Thunder 500D

 

Here are some plots of different TL's using your woofer. The blue broken line is the response that would be expected if the woofer was in a sealed enclosure. The red line is the expected TL performance. The first plot is a tapered tube with the driver at the big end and the opening at the small end. The second is a mass-loaded type where the small end is closed off and a port is added. The mass loaded type will integrate with a midrange easier due to reduced ripple above 110Hz at the expense of a peaky bottom end. The tapered open ended line has a broader gain region but sacrifices the region above 110Hz to ripple. The performance of both these designs can be manipulated to reduce peaking and ripple but at the expense of size and efficiency. Currently they are both in the 60-70 inch length range and a little under a square foot cross section at the big end. The idea is to fold them of course.

For the first plot a LPF of about 100 Hz with a steep slope would be best. It would benefit from the dip immediately after the corner frequency and be well into the stop band before the response kicks back up at 200 Hz. For the second plot a more moderate slope would be fine with a corner frequency as high as 400 Hz. Obviously the closer to the first nasty ripple at 500 Hz, the steeper the slope should be.

The nice thing about a TL is the gain achieved at low frequency (10-15dB!). The problem is the cabinets tend to be very large, especially when getting into drivers 8" and larger. They are really best used to help out systems with small woofers since the cabinet will end up "normal" sized and they can still run with the bigger systems (at moderate power levels).