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Can someone tell me how many octaves a transmission line can cover? Does it reinforce more frequencies than a port? In other words, if I asked, "Will a TL with a full range speaker shift the phase of all frequencies 180 degrees?" ie from 20-20000
Thanks!
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Posts: 3 | From: Fort Washington MD 20744 | Registered: Jun 2000
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posted
I would suggest that it would depend on the length of the TL . There is a good amount of info regarding the issue, as a matter of fact I hope to update my web page regarding the issue. Here's another link http://www.aspen-media.com/transmis.htm#Transmission Line Solution There is more info through the links page on my web site, such as this one http://www.spiceisle.com/audiodiy/
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E.C. Wuz here
Posts: 1057 | From: Vancouver, British Columbia, Canada 'eh | Registered: May 1999
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posted
well i wouldn't call myself an expert on this but i will try my best. phase of the line is totally dependent on the number of turns. i know when it comes to a sign waves when it hits a reflection it changes its phase. by 90 degrees i believe (someone correct me there if i am wrong.) so if you are refering to a transmission line sub enclosure. it all depends on the number of bends in your labrynth. that will determine the phase of the exiting wave. so if you have 4 changes of direction you will be 360 degrees out of phase. i tried........
hopefully this is helpfull. let me know if i can help some more.
posted
I built a TL before. What you do is design the TL around one specific frequency. The length of the tube will be equal to that frequency's 1/2 wave length. In other words, a transmission line enclosure designed to reinforce 60Hz will be one half of 1100/60 (1100ft/sec is the speed of sound) or 9.17 feet. A TL 9.17 feet long will cause a speaker playing a 60Hz tone to constructively interfere with other end of the tube which vents beside the speaker. TL's have a bandwidth of 1/2 octave (1/4 octave above the tuned frequency and 1/4 octave below the tuned frequency). So for a TL designed for 60 Hz, the frequency response will be down by 3dB at 45Hz and 75Hz.
Remember that at every octave above the tuned frequency, there will be a bump in the response. The response of a TL looks like a comb filter.
The Tl that I built worked very well. They are not good for full range. They are well suited for limited bandwidth bass reproduction.
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Posts: 76 | From: Quispamsis, New Brunswick, Canada | Registered: Oct 1999
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I find this interesting my installer was talking about this isnt it suppose to give huge bass peak in the vehicle?? especially if you hit your cabin resonance???????
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