wave boxes

[rco8786 10+ year member]

any of you guys heard of these? the system that is in my truck for the time being(legacy "500"W amp, GodKnowsWhat 10" sub...hey it was free) is in a wavebox. as you can see the equipment is not exactly top of the line, however the guy i got it from had a wavebox made for it and it sounds incredible for being a 120 dollar system(this is when brand new, mind you). But i heard they are hard to make, like the whole inside is a giant maze or something. anyway, just looking for some info on these boxes and why they aren't more popular

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[roots7 10+ year member]

can you get us some pics of the inside? if a shit amp and sub sound good, the setup is worth looking at

 

[rco8786 10+ year member]

ya i'll see if he'll let me take the top piece off tomorrow

 

[rco8786 10+ year member]

ok, instead of tearing up my box to show you guys, i found a diagram on the web:

Here is what the site said about them(the technical name is transmission line)

"Transmission Line

The origin of a transmission line (TL) has roots tracing back to the Stromberg-Carlson acoustic labyrinth, circa 1930. This labyrinth consisted of a long pipe, with the driver mounted at one end while the other end remained open, with a cross-sectional area about the same as that of the driver. In the early 1960's, Dr. AR Bailey experimented with different damping materials and techniques using the same basic concept in these folded labyrinth lines. His work has since become the standard for TL designs. In 1976, AT Bradbury used Dr. AR Bailey's density criteria of 0.5 lb/ft and published his paper describing changes in the speed of sound for different types of damping material such as fiberglass and long fiber wool.

So, what is a transmission line? As the name implies, a transmission line is a long chamber that expends from the back of the loudspeaker. At the opposite end of this line is a vent or opening (generally the size of the driver diaphragm) to the outside of the cabinet. Properly built TL's eliminate the phase cancellation of the driver in any form and make for a nearly perfect sub system. However, TL's are seldom found in car audio because of their size and complexity.

The design of a TL enclosure consists of a taper in the line, making it is possible to eliminate standing waves and resonance common to other speaker enclosures. Eliminating standing waves also protects the driver from harmful back waves that cause distortion and cone breakup. The length of the line does not allow time for air to travel through the chamber and cancel the front-wave. Because of its length, a tuned chamber, much like an open-ended pipe from a pipe organ, is created. This causes a phase shift. It is this phase shift to the rear sound wave (of the woofer) that reinforces the front-wave at the frequencies where the front-wave begins to decrease due to increased air resistance at lower frequencies, very much like a vented enclosure.

The damping of a TL is unlike the "air" spring of a sealed enclosure where the cone has to fight for motion. As a result, the efficiency is better than bass-reflex enclosures, the accuracy is better than acoustic suspension, and the frequency response and linearity is better than all systems.

Designing a transmission line enclosures requires thorough specifications and careful tuning. Suitable drivers for TL's usually have low QTS (0.2 to 0.4), low QES (0.3 to 0.4) and low Fs values. The distance the rear sound wave (of a subwoofer) travels in the enclosure is very specific. Determining the length is based a fraction of the wavelength of the woofers resonant frequency. For example, if the resonate frequency of the woofer used in a TL is 40 Hz, the wavelength of the frequency would be approx. 339 inches (see March 2002 issue, Box Basics II, for formula to determine wavelength). The channel inside the transmission line enclosure must be 1/4, 1/2 or 3/4 of this wavelength, resulting in a channel length of 84.75, 113 and 169.5 inches respectively. Because of the length of the channel, it is often common for a TL to be folded into a labyrinth, making it more compact. If stuffed properly with damping material such as wool, the actual length can decrease due to the resistive effect of the material on the air"

 

[bass_mekanik 10+ year member]

what do you want to know about them the "maze" is just like a big port but don't think that a TL can be used as a port it takes lots of desining to get it right but a TL box can have lots of goods and bads but the best bit is they sound like a ported box with twice as much power as you are giving them and the sq is just like a sealed box with more power

 

[rco8786 10+ year member]

ya, mostly i just wanted to know why they're never used. there's a guy at my school who builds them for people and like everyone wants one. but i guess theyre just too hard to build to be popular

 

[bass_mekanik 10+ year member]

they are hard as hell to build and most subs perform beter in medium sixed ported boxes

 

[Alaxan 5,000+ posts]

Transmission line enclosures are extremely difficult to build properly and take a lot of calculations etc.... the good thing is tho that they are forgiving as far as what type of speaker is in there. The purpose and design of them is specific so that the "length" of the wave is formed properly from the rear of the sub and then projected the same. I built one of these for a house system one time and it was very tedious and massive! The sound tho was WELL worth it. I changed out thru a number of different speakers in the enclosure to see how the sound was and honestly there was not an incredible amount of difference in each other than a slightly louder lower response from the higher end subs I tossed in.