Building a T Line Sub

[BrunsDad5]

I am building a T Line Sub for my Home Theater. I am using an 8 inch sub I had laying around. Can anyone give me some rules of thumb on the size of the cabinet? I wan't to build it so it is standing up against the wall, sub at the top of the face plate. Any sugestions on the size of the channels, port, etc! I have purchased a 4 x 8 sheet of MDF to construct the cabinet out of, so should have plenty of material. I have watch some youtube video's on the constructing these and have not noticed anyone using polyfill or insulation, etc, is that right or should I use some and where? Thanks for all your help, Be Blessed, Jim

[Paul K.]

Re: Building a T Line Sub

Can't really answer your questions specifically without knowing what the woofer's T/S values are. Also useful are your approximate size and shape desires as well as how low you want F3 to be.
Paul

I am building a T Line Sub for my Home Theater. I am using an 8 inch sub I had laying around. Can anyone give me some rules of thumb on the size of the cabinet? I wan't to build it so it is standing up against the wall, sub at the top of the face plate. Any sugestions on the size of the channels, port, etc! I have purchased a 4 x 8 sheet of MDF to construct the cabinet out of, so should have plenty of material. I have watch some youtube video's on the constructing these and have not noticed anyone using polyfill or insulation, etc, is that right or should I use some and where? Thanks for all your help, Be Blessed, Jim

[BrunsDad5]

Re: Building a T Line Sub

Can't really answer your questions specifically without knowing what the woofer's T/S values are. Also useful are your approximate size and shape desires as well as how low you want F3 to be.
Paul

[isaeagle4031]

Re: Building a T Line Sub

You aren't going to fit a tline into that box space. It just isn't big enough. What we need are the measured t/s specs on the driver to see if it will even work in a tline. The f3 is basically how low you are wanting this thing to play.

[diy speaker guy]

Re: Building a T Line Sub

You aren't going to fit a tline into that box space. It just isn't big enough.

He only quoted 2 desired dimensions, so if we can choose the third dimension there's plenty of space. (30 x 12 x ???)

[diy speaker guy]

Re: Building a T Line Sub

I am using an 8 inch sub I had laying around. Can anyone give me some rules of thumb on the size of the cabinet?

Sure, the old rule of thumb is to make the line cross sectional area equal to the cone area and make the line length equal to 1/4 wavelength of the driver's resonant frequency. But be advised, this old rule of thumb is a terrible way to design transmission lines.

What Paul and isaeagle are getting at is that we use software to simulate our enclosures instead of using old, tired rules of thumb. That's why we need detailed t/s parameters, which you have not provided. You won't likely be able to get them from the manufacturer either but you can measure them yourself if you are so inclined.

Type: 8" bass reflex, tuned port enclosur e
Maximum Output: 101 dB

It sounds like your sub already has a box, why do you want to change it? Do you think it's going to be louder and/or play lower in a transmission line? With respect to the size/output ratio, the type of box it is in already is the best bang for the buck possible. It can probably play a bit louder and/or lower but to realize any significant gains the new box is going to have to be a lot larger than the original box was. Besides, it could only do 101 db max from the factory and it's not tuned very low so it doesn't sound like a very robust driver to begin with. This little 8 inch driver is probably better, it comes with published specs, and it's usually only $25 if you can find a coupon code. http://www.mcmelectronics.com/produc...-2421-/55-2421 There are other driver options as well. So there's no need to cannibalize your Klipsh sub.

[Paul K.]

Re: Building a T Line Sub

To sum up what everyone has said, there simply is not enough information on the driver, particularly its T/S values, to model it in a TL, and trying to use Rules of Thumbs to do so will most likely be fraught with bad results.
Paul

[zobsky]

Re: Building a T Line Sub

First measure the T/L specs for the driver. I describe an easy / cheap way here http://zobsky.blogspot.com/2008/01/s...t-jig-for.html

[BrunsDad5]

Re: Building a T Line Sub

To sum up what everyone has said, there simply is not enough information on the driver, particularly its T/S values, to model it in a TL, and trying to use Rules of Thumbs to do so will most likely be fraught with bad results.
Paul

Okay, I give! It is not in a box now, so I need to build something. How about a basic box style, any hints! Thanks, Jim

[diy speaker guy]

Re: Building a T Line Sub

Okay, I give! It is not in a box now, so I need to build something. How about a basic box style, any hints! Thanks, Jim

You already posted the dimensions. Right here. I highlighted the parts that describe the original enclosure.

Type: 8" bass reflex, tuned port enclosur e
Amplifier: 100 watts continuous into 4 ohms
Auto Power On: 2 second ON delay, 15 minute OFF delay
Dynamic Headroom: 1 dB (125 watts into 4 ohms)

Maximum Output: 101 dB
Audio/Video Switch: +3 dB over entire frequency range
Low Pass Crossover: Continuously variable from 40-120 Hz,
24 dB/octave slope above 120 Hz.
High Pass Crossover: Main speakers: line level outputs with switchable high pass between 40 and 80 Hz, 6 dB/octave slope above
120 Hz. Speaker level outputs with fixed high pass at 100 Hz,
6 dB/octave slope.
Phase: Switchable 0-180 degrees
Inputs/Outputs: Line level RCA phono jacks. Dedicated LFE
channel input. High level speaker terminals.
Drive Component: K-1048-K 8" (20.32 cm) driver Fiber-composite cone
Weight: 39 lbs. (17.7 kg)
Height: 14.75" (37.47 cm)
Width: 13.5" (34.3 cm)
Depth: 13.5" (34.3 cm)
Cabinet: Medium density fiber board construction (MDF)
Finish: Matte finish black vinyl
Voltage: 110/120 VAC 60 Hz – Dual Voltage Export Version
230/120 VAC 50/60 Hz

You just need to find the port details. If you can't find them just find the port size that in conjunction with the box size produces a helmholtz resonance at 34 hz, the tuning of the original sub.

But note that if you don't have the original amp (which might have built in digital signal processing) it still might not amount to the original Klipsh product.