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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
g_m_c
443 posts
 
I have had a pair of Meadowlark Blue heron 2's for over 4 years now. They are time coherent, use first-order crossovers, and are transmission-line-loaded bass. I am not skilled in the art of audiophile bs and I have not owned that many speakers. I can tell you the subtlety and nuance these speakers offer are amazing to me. The placement and clarity of instruments and voices, the decay of notes and the general sense of presence can transport me or punch me in the gut. I am still surprised by their sound. Too bad they went out of business.
volvosound
17 posts
 
Anybody familiar with the PMC versions of the transmission line? FB1?
lrsky OP
1,118 posts
 
Unsound,
You lost me, I had to reread my post...your talking about Jim Thiel's comments, right?
He's not the only person to take exception to the efficacy of the TL in loudspeakers, as I understand it. (One reason for the post actually).
Reading a bit, I hear things such as, "Since a bass wave that we're talking about is longer than the line itself, how can this work...." being one of the more popular nay sayer comments.
Then, I read again, as it's been years since I did so with enough interest to remember such...that the wool, (that Bud Fried used) and I prefer for sound dampening in speakers, causes the speed of the bass to change internally to approxiamately (too many factors to be specific), 85% of it's original speed, and that depending on the methods used, the bass tone is 'tricked' (not my words) into thinking the line is actually longer than it is, by an amount of distance which is significant.
Now you see why I posed the question.
I'm about to use a TL in a simple form, and compare it to just ported bass, in a bookshelf--and I'll be happy to pass on my subjective impressions of the quality of bass. (May take a little while).
So, I'd like to hear more of your opinions about the qualitative, (subjective of course)differences.
I do remember my IMF's having some of the most 'musical' bass I'd ever heard...especially given the cabinet size of the speaker I was listening to.

Larry
g_m_c
443 posts
 
intersting comment about the wool. Pat McGinty of Meadowlark used 5/8" wool felt in his front bass firing ports. he also tuned each speaker's ports with instrumentation as the final step before shipping.
bdgregory
1,712 posts
 
the most satisfying bass performance I've heard is from my vintage 1975 Infinity Monitor IIa's. The bass is deep and full without being overwhelming. They are rated flat to 22hz. I still have those speakers but also now have Von Schweikert VR4genIII's which are also said to be TL's. I like them top to bottom, though the bass isn't as full as the monitor IIa's I believe it's more of a room issue than the speaker.
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