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  1. #1
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    what is transmission line speaker

    What is it, how is it different than conventional speakers, and how much do they cost?

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    RGA
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    PMC is one of the best known for Transmission line loudspeakers, but many other speakers utilize the technology in some of their speakers -- simply it can be used to get more bass depth out of the speaker - Audio Note is another off my head that uses transmission line technology to get more bass depth from some of the speakers in their line-up. It is not new and it does not mean better - it all depends how it is used...but I personally think PMC does a good job. http://www.pmcloudspeaker.com/transmission.html

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    SuperPoser Rock789's Avatar
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    is that what bose does with their wave radio?
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    RGA
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    It may very well be and Bose may call it by a different name -- many do. The difference is PMC knows what they are doing when designing and building loudspeakers - Bose knows what they are doing marketing and selling loudspeakers.

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    Loving This kexodusc's Avatar
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    Transmission lines are technically suppose to be a speaker with an enclosure that routs the back-wave of a speaker through a long tunnel that eventually exits via the front of the speaker (though I've seen other, oddball designs that have the "port" elsewhere with much success). The theory of the transmission line is to make a line length equal to 1/4 or 3/4 of a wavelength, therefore the front and rear waves will add to each other upon exiting the front of the line, instead of subtracting...this is good...Awesome bass accuracy, realism, tightness, phase, etc...!!!
    Resonance (Helmoltz) gets to be a problem problem in the low end of T-Lines though, and is very difficult to predict even with good software programs, which makes these designs quite difficult to produce. But when they're done right, there's no substitute IMO, it's as close to reproducing the soundwaves an instrument makes (ie: low bass frequency cancellation, better attack/decay, response, etc...).

    You can typically use the T-Line design with a less "bass-heavy" woofer that perhaps has much more pleasant midrange response and a higher F3 to save some costs. This improves performance as well.

    Inexpensive T-lines sound terrible, and there aren't many out there because T-lines are quite difficult to make properly, no sense in going cheap on the drivers, crossover parts, etc...a cheap T-line probably won't compete with other budget speakers, but once you get above the $3000 range, they really start stealing the show...

    Real T-Line enthusiasts will tell you not to judge the T-Line design by PMC's offerings as they're the so-called "mass production version" of this design, but I think that's a bit harsh, PMC's sound as good or better than most other speakers you'll hear for the money.

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    Quote Originally Posted by RGA
    It may very well be and Bose may call it by a different name -- many do. The difference is PMC knows what they are doing when designing and building loudspeakers - Bose knows what they are doing marketing and selling loudspeakers.
    Bose knows what they are doing designing building and marketing their radio. I don't know if there is any other company out there that could make $50 dollars worth of plastic and electronics sound as good as bose does. I think bose is a case of excellent engineering and very low quality components.

  7. #7
    RGA
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    Beckman -- you can read reviews of the bose Wave radio out of Britain -- several other manufacturers have apparently built far better for much less money -- but their name isn't Bose -- The Wave radio scored the worst in the group tests of similar devices.

    kex

    Who else makes great audiophile calibur T-lines -- I'm surprised by the comment against PMC which is first and foremost a Professional Monitoring company who decided to throw their hat into the hi-fi ring -- that alone may be seen as a cop-out amongst DIY crowds -- but that doesn't mean it's reality -- note there is room for improvement with PMC but that;s true of everyone's products.

  8. #8
    M.P.S.E /AES/SMPTE member Sir Terrence the Terrible's Avatar
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    Quote Originally Posted by Beckman
    Bose knows what they are doing designing building and marketing their radio. I don't know if there is any other company out there that could make $50 dollars worth of plastic and electronics sound as good as bose does. I think bose is a case of excellent engineering and very low quality components.
    What good is excellent engineering when it is lost on cheap parts? That is like saying a woman has got a great body, but ugly face.
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  9. #9
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    Quote Originally Posted by Sir Terrence the Terrible
    What good is excellent engineering when it is lost on cheap parts? That is like saying a woman has got a great body, but ugly face.
    $$$$$ More profit for bose. Not saying the wave radio is worth the money. However, it would be worth the money if it was sold at cost($50).
    Last edited by Beckman; 04-07-2005 at 03:16 PM.

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    Quote Originally Posted by RGA
    Beckman -- you can read reviews of the bose Wave radio out of Britain -- several other manufacturers have apparently built far better for much less money -- but their name isn't Bose -- The Wave radio scored the worst in the group tests of similar devices.
    Far better for much less money, or far better with a lower retail price to the consumer. I don't know if any audio device could be made with cheaper parts than the wave radio and sound better. Not saying it is worth the money, just saying the engineers at Bose did a good job with the low cost parts they were given to work with.

  11. #11
    RGA
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    Beckman -- ahh sorry I get what you're saying now...yes most Bose stuff if they cut the price by 80% would be not bad.

    Boston acoustics has a good unit but it costs $700.00cdn...and I dunno if it can be called good for $700.00

  12. #12
    SuperPoser Rock789's Avatar
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    Quote Originally Posted by kexodusc
    The theory of the transmission line is to make a line length equal to 1/4 or 3/4 of a wavelength, therefore the front and rear waves will add to each other upon exiting the front of the line, instead of subtracting...
    what frequency do these company's use mostly?
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    Forum Regular FLZapped's Avatar
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    Lightbulb

    Quote Originally Posted by MomurdA
    What is it, how is it different than conventional speakers, and how much do they cost?
    This should answer some of your questions:

    http://www.quarter-wave.com/

    -Bruce

  14. #14
    SuperPoser Rock789's Avatar
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    Quote Originally Posted by Sir Terrence the Terrible
    What good is excellent engineering when it is lost on cheap parts? That is like saying a woman has got a great body, but ugly face.
    although, women can't help if they are born ugly or hot, they can keep themselves in shape rather than becoming fat pigs...lol

    I'de take a fit not hot chick over a fat chick with an ugly face
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  15. #15
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    Rga

    Quote Originally Posted by RGA
    Who else makes great audiophile calibur T-lines -- I'm surprised by the comment against PMC which is first and foremost a Professional Monitoring company who decided to throw their hat into the hi-fi ring -- that alone may be seen as a cop-out amongst DIY crowds -- but that doesn't mean it's reality -- note there is room for improvement with PMC but that;s true of everyone's products.
    Come to think of it, I can't really think of many other T-line manufacturers that are as widely known as PMC, except maybe Von Schweikert and MeadowLark - maybe not in your area? You'd usually see companies like Fostex, Seas, Morel, etc hire some designers to make them (or at least come up with designs to help sell drivers). I've mostly seen or read about T-lines in hi-fi shops, usually designed by small regional companies, hand built etc...I don't think you'll ever see many large T-Line manufacturers until the likes of B&W or Paradigm, or other already-established speaker companies start mass producing them (if they haven't already). I would think start-up costs and having little name-recognition would be pretty hard in a market where the bottom price is $2000 USD. Probably not many people willing to part with $2000 on a whim like you see when people throw their money at some start-up Web-based consumer direct companies like Axiom, Rocket, etc...And I'm not sure I'd want to see someone come out with a $300 T-Line.

    The DIY crowd rarely makes a habbit of saying anything bad about commercial speakers from what I've seen (with the exception of Bose, of course). Usually they find a commercial speaker they like, and try to make something comparable for cheaper. The snobbiness that does exist is usually limited to favorite driver companies.
    I was referring to T-line enthusiasts I've met on the web and in person...It just seems there's two camps: the PMC crowd and the non-PMC crowd. Your assumption could very well be correct, maybe in their eyes PMC has "sold out". Being successful is often the kiss of death.
    I like most PMC speakers I've heard.

  16. #16
    Music Junkie E-Stat's Avatar
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    Quote Originally Posted by RGA
    PMC is one of the best known for Transmission line loudspeakers, but many other speakers utilize the technology in some of their speakers...
    One of the commercial pioneers over thirty years ago of TL speakers was the late Irving M. Fried. He designed and sold many a TL line speaker under the IMF brand name. Later in the 70s, ESS marketed some TL speakers as well.

    When done right, it is a relatively expensive way to get good bass response. I am amused with Bose's notion that somehow they came up with the "acoustic wave" principle. I do admire their marketing expertise, if nothing else.

    rw

  17. #17
    RGA
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    Audio note uses a Quasi horn T-Line in their AZ series floorstanders and the review said it sounded very much like Quad but with bass.

    The original Snells had a Wave Launch system -- hmmm wonder is there is a resemblance?

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    Loving This kexodusc's Avatar
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    I've heard of some odd-ball designs that use T-Line's for the tweeters etc, never actually listened to these.
    I should add that T-lines aren't ONLY a means of improving bass, most T-Line enthusiasts (myself included) would argue the bass improvements are the smallest benefits of a T-Line, though this is often the first thing picked up in initial listening tests because it is such an improvement.

    Some of the rest of the theory (which I'm not even going to pretend to fully comprehend) involves preventing the back wave of the woofer from bouncing off an interior wall so as to radiate back into the room through the thin cone of the woofer as in sealed and ported enclosures. These reflecions or echoes add to coloration quite a bit. Instead this energy is tranferred through the system in an a deliberately organized fashioned "in synch" with the forward wave - I have a book that has some research on harmonic ringing or some such term, but basically it's talking about the back wave radiations spilling over into all frequencies.

    Also, unlike sealed and ported enclosures where resonances can never be fully eliminated (only managed and diminished), a good T-line theoretically removes ALL resonances because there's no pressure in the system to excite the resonances - again, reduced coloration. The result is a more stable, purer mid-range performance. Problem is some less expensive T-Lines make compromises, and this isn't always the case - these shouldn't be called T-Lines IMO, but oh well.

    The T-Line also provides the driver coil with more control (ie: always within the accepted limits of its magnetic field) - less distortion, higher SPL, etc.
    Ever notice how some speaker's sound changes as you crank the volume? Often this is caused by thermal compression on the driver coil as heat builds, which is also reduced in a T-Line (better dissipation).

    Many T-line designs only concentrate on the bass aspects, not the rest of the possible benefits...a well designed T-line should incorporate all the advanatages.

  19. #19
    RGA
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    KEX

    That's interesting because parts of those statements seem to be what the AN boxes are doing the AZ series has a huge cut-out about 3/4 the way up the back of them --- your cat could jump inand get stuck -- there's no port just a big square hole and you can see down and inside them...Though my understanding is they use a semi horn as well to raise sensitivity -- a person more knowledgeable than me basically said it's a Semi horn loaded T-Line. I have not heard the AZ series but next time I'm out there It might be interesting.

    They call it "Two-way folded, parabolic, rear-loaded, quarter-wave quasi-horn-loaded floor-standing loudspeakers" LOL

    Suppose to be very room firendly as well.

    A reviewer said

    "Audio Note AZ-Three is a two-way speaker system of a hybrid transmission line, folded horn, and bass reflex design. Dimensions are 1000*280*344 mm (H*W*D). Crossover frequency is 4 kHz. The tweeter is the 25-mm impregnated cloth dome, and the woofer is the 200-mm paper cone. The speakers are nicely efficient, about 95 dB, according to our measurements. The shape of the bass response is dictated by the cabinet design providing installation versatility of the speakers. The boost at 3.5 kHz is possibly caused by the flexure of the paper cone; the corresponding coloration is virtually inaudible. As a whole, the frequency response looks well-balanced. The harmonic distortion in the essential frequency range is no more than 0.5% both at 0.5 (88 dB) and 1 Pa (94 dB) signal.../...In accurate, deep, and, above all, clear bass is not surprising at all; this is the family feature. In general, the fundamental advantage of AZ-Three is an excellent image clarity, which is due to the low harmonic and intermodulation distortion. The small value of the latter is responsible for the excellent quality of choral vocals, which is a rare and significant advantage even for high-class speakers. The voices in the monolith stream form a well-readable pattern, the ear relaxes listening to the harmony unobstructed by the characteristic dredge. I won't have the heart to speak about genre preferences; both rock and the most complicated classical music are played easily. Treble is very nice; its exhaustiveness, austerity, and the absence of unnecessary accents is to the audiophile's taste. The sound stage imaging is stable across the front. The sound stage is even as if it grows as a single solid wall; the third dimension is not thoroughly elaborated though. Nevertheless, the image is shaped rather eloquently. Note that the spatial effects are strongly dependent on the speaker position in the room. In this connection, we strongly recommend to follow the placement instructions given by the manufacturer.

    In addition to the genre neutrality mentioned above, the indifference to the room size should be mentioned as an advantage. The speakers can be safely placed in a very small room without a risk of spoiling the bass. Their high sensitivity gives one a free hand in choosing an amplifier; in particular, a combination with a valve amplifier can be very interesting." ( by Dmitry Dmitrokopulo, Stereo & Video, November 2000, page 56)

    Makes me want to hear it now. (pictures are of the cheaper smaller AZ two - $1kUS so I do want to hear it for the money.
    Attached Thumbnails Attached Thumbnails what is transmission line speaker-az-2-pic.jpg   what is transmission line speaker-az-pic-3.jpg  

  20. #20
    Silence of the spam Site Moderator Geoffcin's Avatar
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    Quote Originally Posted by RGA
    KEX

    That's interesting because parts of those statements seem to be what the AN boxes are doing the AZ series has a huge cut-out about 3/4 the way up the back of them --- your cat could jump inand get stuck -- there's no port just a big square hole and you can see down and inside them
    You've just described a typical open-backed Guitar cab. Not very high-tech, or very good for uncolored music reproduction, as these are DESIGNED to be colored. Highly efficient though.
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  21. #21
    RGA
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    Well I guess we'll have to hear them to be sure -- After all they have been compared to QUAD type of sound (So leading edges and transients will be fast)-- while others compare them to the single driver LOTH??? A little all over -- so I shall have to go and hear a set sometime. If there are say ten aspects of sound and they add 2% colour and gain 40% on the all the others I'll take that...And of course if one is forced to buy SS well that is too much of a disadvantage right off the bat.

  22. #22
    Silence of the spam Site Moderator Geoffcin's Avatar
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    That looks pretty bad

    Quote Originally Posted by RGA

    Makes me want to hear it now. (pictures are of the cheaper smaller AZ two - $1kUS so I do want to hear it for the money.

    With the glue overdrip, and the sharp edges. I would like to say amateurish, but that would be an insult to amateurs. Whoever designed/built these speakers needs to get a different hobby.
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  23. #23
    Silence of the spam Site Moderator Geoffcin's Avatar
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    You can campare them to anthing you want.

    Quote Originally Posted by RGA
    Well I guess we'll have to hear them to be sure -- After all they have been compared to QUAD type of sound (So leading edges and transients will be fast)-- while others compare them to the single driver LOTH??? A little all over -- so I shall have to go and hear a set sometime. If there are say ten aspects of sound and they add 2% colour and gain 40% on the all the others I'll take that...And of course if one is forced to buy SS well that is too much of a disadvantage right off the bat.
    They are still a pair of speakers stuck into the front baffle of a box. The box looks horribly unbraced too, pretty much guaranteed to vibrate pretty badly no matter if you use tubes or SS to drive it.
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  24. #24
    Silence of the spam Site Moderator Geoffcin's Avatar
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    Quote Originally Posted by RGA
    KEX

    A reviewer said

    "Audio Note AZ-Three is a two-way speaker system of a hybrid transmission line, folded horn, and bass reflex design.Dimensions are 1000*280*344 mm (H*W*D). Crossover frequency is 4 kHz. The tweeter is the 25-mm impregnated cloth dome, and the woofer is the 200-mm paper cone.
    An open back speaker box is now a " hybrid transmission line, folded horn, and bass reflex design." What a load of marketing crap!!
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  25. #25
    Loving This kexodusc's Avatar
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    Quote Originally Posted by Geoffcin
    With the glue overdrip, and the sharp edges. I would like to say amateurish, but that would be an insult to amateurs. Whoever designed/built these speakers needs to get a different hobby.
    I dunno, but I've opened up $800 Paradigm's and B&W's that make these look like the Nautilus...the gluing is kind of sloppy...Dado blades really should be used...contact cement works better, and that looks like an inexpensive ply or, worse, particle board.
    Quote Originally Posted by Geoffcin
    The box looks horribly unbraced too, pretty much guaranteed to vibrate pretty badly no matter if you use tubes or SS to drive it.
    I dunno, I can't see much pressurization with a window that big in the back...the front baffle is hopefully 1"thick or more with an 8 " woofer there, but otherwise it should have many problems

    They can call i whatever they wan't...that to me looks like a textbook folded horn design with a tweeter. Fostex has had a lot of designs similar to this available for years...Hmmmm...wonder what drivers are in these speaker...could they be Fostex?.

    Despite the worksmanship in the window (which is only an eyesore if you staring at the back) these probably aren't that poorly constructed at all...the veneer job looks good, that's the toughest part usually. Hopefully there's a brace every 8 to 10 inches if it's particle board or softer ply. These probably have a very unique sound...I'd like to hear them.

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