Transmission line speakers and related

[rwnano]

Anyone who has experienced these speakers? Feedback on the above mentioned? Thank you

 

[reignofchaos]

Had a PMC - now sold. Couldn't get used to the bass. Sounded really unnatural. Other than that it was a really good speaker.

 

[Yelamanchili manohar]

I like transmission line bass. Have PMC's again. And like what they do in the bass. Then when it was time for my next speakers, got a transmission line DIY'ed for me. But difficult to get it working well, design wise.

 

[rwnano]

I have fried transmission line speakers and focal 706 v2. Both are two way speakers.The transmission line speakers have deep tight bass. They also literally soak up the current and volume . The dial on the amplifier at which the Focals would be very loud....those volumes are just sponged up by the transmission line speakers

 

[grindstone]

Good and bad examples like any other speaker, but, done-well, I prefer TL's over "normal" reflex or sealed designs. If I never heard big front loaded horns, I might still be listening to TL's and ribbons. They roll-off shallower than reflex, are almost always damped well, and can energize a room to achieve an effortlessness that comes from a terminus near a corner. Definitely sensitive to resistive material filling density/locations.

The tradeoff is usually using low-sensitivity drivers (so they go low) and most often people try to get too much low-low out of them (because they can). I wish everyone would experiment with a small single driver and DIY every kind of enclosure for it...once you play with this stuff, it's formative. Loading-up a pipe with polyfill sort of "homogenizes" and knocks-down the lower impedance peaks of the box that the amp sees at it's terminals, too. There are degrees of this stuff, depending on how dense the filling is (and how literally "stuffy" it sounds)--it goes from the double-humped reflex signature to a single-lower-Q hump and ultimately can almost wash-out completely aperiodic if (over-)damped.

The other thing is the way the language/jargon has been abused in the last maybe 30 years. To engineers, "transmission line" has a very specific intent regarding termination of the lines. In audio anymore (esp DIY), it's best to not trust the semantics/labels. Some people still think TL means only what Bailey was talking about ages ago. My point is to not be romanced by one person/vendor's specific manifestation to be the same as everyone else's in 2024.

There's a place in pipes where they indeed can sound that way (when they're too long, damped insufficiently, and/or made of ringing materials)--hollow, echoey, closed, megaphone-ey. That can make me crazy, too. It's when you're trying to beat physics with little drivers and long pipes that it's clear that nothing is free They can also be very open--much more open than a sealed box unless the sealed tends toward infinite-baffle-big.

With big, sensitive drivers, they can be clean and effortless and huge in presentation--at a cost of a bigger cabinet. WIth the right big-box reflex designs and abnormally large ports and additional internal damping (so it's less-pure-reflex), a smaller box (than folded pipe/TL) can approximate the same presentation. With little (think 3-6") drivers, pipe designs can be a sort of "parlor trick" to enhance not just frequency but the body of large soundbodies. (The fullrange driver people use that to advantage in many things.)

But yeah, if you are a fan of OB, it's going to be objectionable. Most will never be confused wtih OB. Here's a YT video of a small 2-way (6.5" W) with a bunch of different program material selections that IMO gives a really solid demonstration of both the good and the bad--depending on what's playing. It's a great example of nothing in audio being free. Maybe the largest indictment(s) are attributable to the compact-sized 2-way topology itself in this particular case. If the LF is separated into an actual pipe/TL woofer in a 3-way, it's easy to entertain a different level of performance as well.

 

[keith_correa]

Here's a YT video of a small 2-way (6.5" W) with a bunch of different program material selections that IMO gives a really solid demonstration of both the good and the bad--depending on what's playing. It's a great example of nothing in audio being free. Maybe the largest indictment(s) are attributable to the compact-sized 2-way topology itself in this particular case. If the LF is separated into an actual pipe/TL woofer in a 3-way, it's easy to entertain a different level of performance as well.

In the video that you linked to (thanks!), the speaker is built as a folded TL and hence IS a transmission line. Built as a 2 way or 3 way, given the same woofer, the physics of the TL enclosure and type of line employed remains the same for both topologies. The thing with that video/build is that the TL was originally built/optimized for a different driver and for the video, a different driver was retrofitted in the same line so the original line may not be optimal for the retrofitted driver.

 

[grindstone]

Apology for confusion, but I don't understand the notion of using the same woofer in the same line for mids and then another one for bass (?)--there would be little benefit to that. You'd use a proper woofer in a similarly-tuned line, and the 6.5 would have a different rear load (if a pipe too, a shorter one). All I was trying to say is that, if you get the lows off the mids by using a 3-way, mids are cleaner and you can use a real woofer that's not straining to do lows so it's cleaner, too. Three-way necessarily becomes a bigger box.

 

[keith_correa]

Apology for confusion, but I don't understand the notion of using the same woofer in the same line for mids and then another one for bass (?)--there would be little benefit to that.

I wasn't trying to say that at all.

You'd use a proper woofer in a similarly-tuned line, and the 6.5 would have a different rear load (if a pipe too, a shorter one).

IF the 6.5 were to be used as a mid [which I THINK is what you are saying], I see little to no benefit to use it in its own TL for the typical mid frequencies it would be needed to do. Of course, sealed TL's are very much possible but again...

All I was trying to say is that, if you get the lows off the mids by using a 3-way, mids are cleaner

Not necessarily true always, but that is food/fodder for a separate discussion.

and you can use a real woofer that's not straining to do lows so it's cleaner, too. Three-way necessarily becomes a bigger box.

There's no "strain" if the TL is tuned properly using modern TL mathematical models unlike the old Bailey models.

 

[Passive_audio_enthusiast]

PMC is the first brand that comes to mind when it’s about transmission line. However after listening to several old speakers and new ones from different brands to me T+A is another great option. British brands have lot of positive press and to me German brands really are lot behind in terms of marketing however they are really well engineered.

 

[grindstone]

I wasn't trying to say that at all.

IF the 6.5 were to be used as a mid [which I THINK is what you are saying], I see little to no benefit to use it in its own TL for the typical mid frequencies it would be needed to do. Of course, sealed TL's are very much possible but again...

Not necessarily true always, but that is food/fodder for a separate discussion.

There's no "strain" if the TL is tuned properly using modern TL mathematical models unlike the old Bailey models.

OK, this seems to spiral ever-outward from my point My point is, that I _like_ the YT speaker experiment but the faults I find in it are about half due to it being a 2-way asked to play everything but the bottom of the piano. Take that same thing, shorten the pipe for the 6.5, put a pipe with a bigger driver under it, cross it someplace near the top of the modal region, and it'll fix half of what I have problems with (detectable through device chains of YT, anyway). I like the speaker experiment, it showed enough promise to listen to IMO. It also sounds a bit wooly and yes strained to me when it's trying to deliver low-low bass and vocals on certain tracks. You can hear the driver is crowded and you can hear some box mud--even through YT (but not near as much as some other, lesser implementations). While completely open to having to modify that impression given an in-person audition, I'm sticking to it absent that.

Excepting limited operating ranges of a couple recent manufacturers of advanced driver motors, it's been a truism for around 90 years of direct radiators now that excursion is just about proportional to distortion--as PWK taught us all in the 60's and hammered-home afterward. Again, absent the special case expensive driver motors and limited operating ranges, if it moves, it distorts. Volume displacement equal, little drivers have to move more than big ones. That's the benefit to not flogging little drivers for the bottom 5 keys of a piano and trying to have it also reproduce the vocal range. If you're just having fun being argumentative with corner cases, OK--you got me. Otherwise, I'm at a loss for why you're bringing all the impedance. It's become pretty-much no longer a worthwhile way to spend time for me.

And if you've not tried a small pipe on a low-mid (~200+), try it. It's another thing worth hearing and experimenting with, IMO.

 

[keith_correa]

If you're just having fun being argumentative with corner cases, OK--you got me. Otherwise, I'm at a loss for why you're bringing all the impedance. It's become pretty-much no longer a worthwhile way to spend time for me.

What is prompting a response like this? Argumentative? So your point of view is a pov and my counter/response to that is an argument? Really? Even if were an argument, so what? You argue, I argue - that's part of life in a forum.
Impedance? To what? I really don't see what I am obstructing.

And if you've not tried a small pipe on a low-mid (~200+), try it. It's another thing worth hearing and experimenting with, IMO.

Maybe I will someday. Thanks for the pointer but my opinion is that a small (depending on your definition of small) pipe is just the same as a regular box - sealed or ported and we are talking TL's here.