Transmission Line design

[joetama 5,000+ posts]

whatcha google exactly?

Transmission Line Design... //content.invisioncic.com/y282845/emoticons/rolleyes.gif.c1fef805e9d1464d377451cd5bc18bfb.gif

 

[Megalomaniac 5,000+ posts]

funny man //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif

 

[terra 5,000+ posts]

im interested...

 

[joetama 5,000+ posts]

funny man //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif

I'm serious...

 

[twisztdauthorit 10+ year member]

sorry for the shitty pics, there off my camera. This was my t-line designed for 1x10"

Some calc got messed up and port was 2x as large so im gonna replace the 1x10" with two stronger ones. This is for my room and is tuned to 28hz i believe. first t-line and i used a tapered design because i spent days drawing out other ones but it just didn't work.

It is considerably louder and it hits 26-32 hz like a mofo. My clothes hangers start to rattle in my closet on the other side of the room.

So anyways this is just a cheapy lil 10 off around 120 watts.

The sub bottoms out way to much for me so i need a better handling sub for max potential.

I can take more pics if you like or measurements,

 

[twisztdauthorit 10+ year member]

bump

 

[joetama 5,000+ posts]

Aparently what I posted was wrong.

I posted it because no one else was posting much information. So, since I have no idea I will delete this and hope that the people who do know what they are doing, or say they know what they are doing will enlighten us...

 

[Immacomputer 10+ year member]

Two basic rules...
Ready...

TL area should be equal to or a little greater than the Sd of the drivers.

TL length should be 1/4 the wavelength of the Fs...

Both of those rules are not good to follow and are way over generalized. That is just like saying:

Ported enclosures for 12" subs should be between 2-2.5 cubic feet.

Ported enclosures for 12" subs should be tuned between 32-35hz.

It's a terrible over generalization that may work out occasionally but will very rarely be optimal.

 

[Megalomaniac 5,000+ posts]

Both of those rules are not good to follow and are way over generalized. That is just like saying:
Ported enclosures for 12" subs should be between 2-2.5 cubic feet.

Ported enclosures for 12" subs should be tuned between 32-35hz.

It's a terrible over generalization that may work out occasionally but will very rarely be optimal.

i replied to your pm last night bro

 

[twisztdauthorit 10+ year member]

i agree with the 1/4 wavelength rule but i dunno bout the port area rule

I have read that your port area should be tapperd down to 1/2 to 3/4 of your speaker surface area to reduce some type of backbouncing waves or something.

 

[joetama 5,000+ posts]

Both of those rules are not good to follow and are way over generalized. That is just like saying:
Ported enclosures for 12" subs should be between 2-2.5 cubic feet.

Ported enclosures for 12" subs should be tuned between 32-35hz.

It's a terrible over generalization that may work out occasionally but will very rarely be optimal.

That's why I called them Basic... //content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif

 

[Immacomputer 10+ year member]

But they do more harm than good. //content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif

Spreading around information like that leads to people thinking they know what's going on when they really are just making a pipe organ chamber with a sub that drives it into resonance.

 

[twisztdauthorit 10+ year member]

lets get some more info on these t-line boxes...

 

[joetama 5,000+ posts]

But they do more harm than good. //content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif
Spreading around information like that leads to people thinking they know what's going on when they really are just making a pipe organ chamber with a sub that drives it into resonance.

I admit that I don't know much about TL's. I'm doing reading and trying to understand them. Several places that I have found list these rules as 2 basic principles that make up a TL. Is that wrong?

 

[buildmeabox 10+ year member]

I hope this helps.

I've always found transmission lines intriguing, not only because of their attributes, but also because for so long their design was cloaked in mystery and conjecture, rules of thumb, and sometimes outright bunk. The recent works of Martin King and Augspurger, among others, have removed the veil on proper design-or at least made it somewhat more transparent.

Although their design process can be tricky, transmission lines provide an alternative solution to some basic acoustical challenges. Half of a driver's acoustic energy radiates from the back of the cone. In a sealed design, an attempt is made to dissipate this unwanted energy by absorbing it in stuffing, but in many cases a significant amount of energy reenters the cone- delayed in time, and revealed as response peaks due to internal standing waves. All of these effects cause distortion of the original signal.

A transmission line functions by using this wasted and unwanted acoustic energy in a positive manner. By encouraging standing waves of a single low frequency, and providing an opening (or terminus) out of which these standing waves can escape, the bass response of the driver can be extended. At the same time, the transmission line reduces the energy that reenters the cone and causes distortion. I chose the classic tapered transmission line design for its characteristic nearly linear impedance, uncolored sound, good bass extension, and simplicity of construction.

The first thing I noticed on the TL build was the lack of stuffing, this is the second most important part of the TL, the first is keeping the box linear, the type of material and amount of material affect the sound.

Everything I've read about TL's performance is subjectively superior to that of both sealed and vented enclosures. But Vance Dickason stated in his "Loud Speaker Design Cook Book", "it is evident that TL group delay performance, which is a measure of transience, is very similar to a well-damped sealed box and as with a sealed box, superior to that of a vented enclosure". Martin Colloms, founder of Monitor Audio in England, believes the TL performance is no better than a properly constructed vented enclosure. It seems that everyone has their own opinion on the matter, less filling-tastes great. Currently I haven't seen any kind of 6th or 8th grade mathematically accurate design table as can be found/used for other box designs. You be the judge and audition the Bose Wave radio, its based of a TL design.

I hope this has shone some light, some of the info came from Vance Dickason's book and partsexpress.com projects page.