Transmission-line speakers

[sergeauckland]

My question contains word "vent", so closed boxes (including B&W Nautilus) are out of question.
I asked which TL loudspeaker with vent has no output from the vent?

No idea of current production, but the Bailey designs of the 1970s were claimed to be indifferent to vent being open or closed.

I suspect that all modern so called TLs except for the Nautilus use the vent for bass reinforcement as that makes them smaller and easier to sell.

Just because something is called a Transmission Line in a marketing brochure, doesn't make it one.
S

 

[Vladimir Filevski]

No idea of current production, but the Bailey designs of the 1970s were claimed to be indifferent to vent being open or closed

The important word is "claimed"! No, Bailey TL is very different with vent open or closed!

Just because something is called a Transmission Line in a marketing brochure, doesn't make it one.

Until the B&W Nautilus come out, all loudspeakers based on 1/4 lambda resonance were called Transmission Line, including Bailey's loudspeaker. So, please stop trying to be more Catholic than Pope (i.e. Bailey) and accept the name which all world accepted long time ago.

Besides, I am not convinced at all that B&W Nautilus (snail) is a true Transmission Line. Do you have any evidence (measurements) for supporting the idea the Nautilus is true TL? Otherwise, you are believing in pure marketing ferry tales.

 

[Emlin]

The important word is "claimed"! No, Bailey TL is very different with vent open or closed!


Until the B&W Nautilus come out, all loudspeakers based on 1/4 lambda resonance were called Transmission Line, including Bailey's loudspeaker. So, please stop trying to be more Catholic than Pope (i.e. Bailey) and accept the name which all world accepted long time ago.

Besides, I am not convinced at all that B&W Nautilus (snail) is a true Transmission Line. Do you have any evidence (measurements) for supporting the idea the Nautilus is true TL? Otherwise, your "evidence" is pure marketing ferry tale.

So you accept that there is such a thing as a true transmission line speaker, yet want to use the term for non-transmission line speakers as well. Crazy!

 

[sergeauckland]

I'll call things by their technically correct name, regardless of how anyone else may use the words. A 1/4 wave resonant column is NOT a Transmission line.

As to the Nautilus, the snail is long, tapered and internally damped, with no vent, so a real TL. As far as I know , there have been no independant measurements published.

S

 

[Vladimir Filevski]

So you accept that there is such a thing as a true transmission line speaker, yet want to use the term for non-transmission line speakers as well. Crazy!

No, I never said that! On the contrary - I am confident that real Transmission Line loudspeaker is not possible at all!

 

[Vladimir Filevski]

A 1/4 wave resonant column is NOT a Transmission line.

So you are saying Bailey got it wrong?

 

[Vladimir Filevski]

As to the Nautilus, the snail is long, tapered and internally damped, with no vent, so a real TL. As far as I know , there have been no independant measurements published.

Being long, tapered and damped does not make it real TL! Evidence (measurements), please!

 

[Emlin]

No, I never said that! On the contrary - I am confident that real Transmission Line loudspeaker is not possible at all!

Ah well, you against reality then.

 

[Vladimir Filevski]

Ah well, you against reality then.

Show me the reality then - where are the measurements?

 

[Emlin]

Show me the reality then - where are the measurements?

Where are yours?

 

[ryanosaur]

Like all other threads here... here we are at that vital moment where puerile responses overtake mature conversation.

Bye.

 

[Vladimir Filevski]

Where are yours?

You wrote that real TL loudspeaker is a real thing before I claimed it not exists - burden of evidence is yours, because it is impossible to prove that something do not exist:
https://www.logicallyfallacious.com/logicalfallacies/Proving-Non-Existence

 

[Salt]

Last attempt doing some clarification, as the discussion's now running circles because of different interpretations of terms, so I asked Wiki:

... "Although the result may require a lot of modeling and testing, the starting point is usually based on one of three basic principles.

- Filling the entire tube treats the TL as a damper, aiming at completely eliminating the rear wave.
- Filling half the cross section throughout the line's entire length treats the TL as an infinite baffle, basically damping high frequencies and wall-to-wall resonances.
- Filling the tube from the driver to half the tube's length aims at a quarter-wave resonator, leaving the fundamental tone with its velocity maxima at the open end of the tube intact, while damping all the overtones."....

IMO most of us are after the resonator for bass enhancement.

Besides, there is a new approach with a concept that looks like classic BR but behaves like TML, available for DYI.

Peace

 

[Vladimir Filevski]

Actually, definition for Transmission Line loudspeaker is very simple, if we don't forget the key word "Transmission".
Well, if there is transmission, then it should go from the source to the end exit (port), shouldn't it? The sole purpose of Transmission Line is to transfer energy from the start to the end of the same Transmission Line - just think about how electric power (230 or 110Vac) comes in your house - along the electric transmission line, no? Or how the high power radio frequency signal go from radio transmitter to the antenna. For the initiated - both examples can be accurately computed with the "Telegrapher's equations" (Oliver Heaviside, in 1876).
So, could the traditional vented loudspeaker TL (based on ¼ wave resonance) be called Transmission Line? Yes, because it literally transmits energy from the woofer to the port, although there is dominant ¼ wave resonance. On the other hand - can the real Radio Frequency Transmission Lines exhibit ¼ resonance? Yes, happens all the time. Have you ever heard of ¼ wave antenna?
Now, could Nautilus (snail) be called true “closed Transmission line”, which have not any resonance? No, because the physics laws can’t be broken. Nautilus must exhibits ½ wave resonance, although attenuated. So, it is not-ideal Transmission Line (closed), much in the same way traditional vented TL loudspeakers are not-ideal TL even if they are heavily stuffed.
I have to quote Martin J. King, which opinion is that Nautilus (snail) is more marketing than technical advance in speaker design, with no advantage over the simple closed box.

 

[ElJaimito]

I have followed TL designs ever since Dr. Bailey's original '72 papers in Wireless World. I found several uses for long-fibre wool, but so did moths.
The original Bailey design, which I heard in person, did manage very remarkable LF response, but, do we need to go that way now? Let's recall that Thiele and Small's publications were roughly contemporaneous with Bailey's designs. We now have a much more systematised set of guidelines.

I have never heard a modern TL speaker that I felt happy with, but then there's loads I have not heard. These TL are only really loosely analogous with an electrical TL, where the aim is to have an impedance match, the characteristic impedance, so that all power entering is eventually discharged in the load and not the line. An electrical TL is usually vastly longer than the wavelength being transmitted, and as with so many other aspects of acoustics, that is rarely - probably never - the case with any LF "TL" design. The long-fibre wool was supposed to reduce the speed of transmitted pressure waves by some 70%, shortening the required tunnel length.

I am certain that as with every other design framework, it is possible to make a "TL" speaker sound very good. I cannot see that the cost and complexity is justified nowadays. I have not liked any PMC speakers I have heard, and can't see/hear how they justify the price. Yes they put a lot of fiddly work into them, but that's not my problem. The original Bailey design did manage very remarkable LF response, but again, do we need to go that way now?

 

[ElJaimito]

Wrong. If you close vent of such TL, the low frequency output will drop. If it didn't matter, why Baliey left vents open?

I think you are correct. The vent was part of the terminating impedance matching in the original Bailey design, AFAIR (it's many years since I read the articles). Although there was no actual output, if the vent was sealed there would have been as it caused a mismatch. Sort of Zen really...

 

[MartinV56]

Pioneer B20FU20-51FW Full Range
"Bofu" Nelson Pass design

 

[Everett T]

Pioneer B20FU20-51FW Full Range
"Bofu" Nelson Pass design

Ok? The drawings note "tweeters", any other information as the way it looks now its just 'another' average full range speaker?

 

[Salt]

Pioneer B20FU20-51FW Full Range
"Bofu" Nelson Pass design

Obsolete design of TML and desastrous measurement (where is the output of the line below 70 Hz? or is it that skinny?).

 

[Salt]

Ok? The drawings note "tweeters", any other information as the way it looks now its just 'another' average full range speaker?

The drawings note w/ tweeters. Not that into it, but is it not to meant without?