Transmission Line Bass


As a long time proponent of good bass without subs, I like tinkering with different ways of approching the age old problem of recreating all energy below 100Hz.
Seriously, if you look at loudspeaker responses, everything seems goes to hell just below that point, swinging wildly in output response, almost independent of many of the typical factors that would be indicators of performance.
So, the question.
Who among us has had extensive Transmission Line Bass Experience in listening, (like me with the IMF's in days gone by, with Bud Fried being a wonderful mentor to me).
In Jim Thiel's lab, one time he told me 'candidly' that Transmission Line Designs 'in theory' don't work. (Another discussion for another time). But he, like me was a bass freak of the first order, loving a rich full bottom end, hence some of his equalized designs early on. They were an all out attempt to bend the laws of physics.
So, what do we think of Transmission Line bass--so, if you're familiar with the sonics though actual listening, and can express first hand opinions let us hear your impressions of the differences between ported, passive radiators and transmission.

Thanks in advance...

Larry
lrsky
I have yet to hear a speaker that uses a transmission line enclosure reproduce natural sounding bass. I do think that TL's can produce deep and powerful bass when done correctly, but something about a TL system simply does not sound "right" to me. My current speakers use an aperiodic vent which, it seems, is pretty rare. They produce the most natural bass I've ever heard.
Dodgealum,
Its tough for most people to separate what sounds correct, from what sounds like the thing that they're most used to hearing.
While designing, a tragic error can be to use a previous model, OR another speaker as a reference--don't get me wrong, it's almost impossible not to. However, as Michael Keaton said in Multiplicity, 'a copy of a copy of a copy is just not rignt.' Therin lies the danger. I had to, since I didn't happen to have a live band here, use a speaker, and I used the Sound Lab A-1--and its no surprise that my loudspeakers sound was natural, flat, while still musical, as the Sound Labs sort of set the bar in those areas.
However at some point you have to, in your mind's eye, still be able to hear/know what that bass being bowed or plucked, really sounds like, and have a really good sonic memory. All this is my way of asking, 'Does it sound like music, or what you're used to hearing from speakers'...and THAT is a distinction with a difference to me.
Then there's the 'Transmission Line Bass' has its unique sound,' camp. I agree, and I like that sound, and think that in some ways its more natural sounding.
The funny part about bass is that, bass gets its character from the midrange--2,3,4,5 and more octaves above the dominant tone that's expressed by the instrument.
When a double bass's open E string is plucked and 41.6Hz is put out there, it's really 83. whaever, then 166.whatever Hz and 332.Hz then 664Hz thats giving it so much of its tonality. Bass is curiously, or maybe not curiously the most complex aspect of music--partly because it's centered in our human hearing curves center--kind of.
Whatever, just rambling now.
More thoughts...your input(s) have been great!

Larry
I have a transmission line speaker built by Serious Stereo which uses the Altec 604 duplex driver and 2 bottom vents. I must say that the bass is much better than the other ported speakers I have had in the past. It goes down into the mid 20hz before starting to roll off. It is very tight and nuanced. The downside is that the enclosure is 11 cubic feet so the speaker has a rather low WAF.
I have Fried Studio 7's. I love the transmission line bass. It just sounds more authentic, not bloated or artificial in any way. Some here cite size as limiter and my Fried's are pretty substantial, but you can get good TL bass with smaller enclosures and folding of the transmission line. Another plus for TL enclosures, is because the internal transmission line construction naturally lends itself to a stiffer cabinet.

Ben