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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
martykl
3,578 posts
 
Unless the bass is generated adjacent to the wall, in-room cancellations will create the swing in FR you cite in your OP. So....either find a loudspeaker designed for use against a wall, correct bass response with a room correction device (e.g. Audyssey), or drop the objection to subwoofers.

Marty

That said, good luck with the TL hunt - I do like some of these designs, particularly the aforementioned IMF and Fried. Alas, the listening room is a cruel mistress.
lrsky OP
1,118 posts
 
JohnK,
You've stated the very thing that makes this whole debate an ongoing one...
Just wondering, as a 50Hz tone is 25', how would that be possible? (To build a T Line as long as a bass wave). A 25Hz 50'...and so on. This is what Jim Thiel was referring to--whether valid or not, with regard to our ability to build such a device. (I refuse to discuss most theory, as people ususally know, myself included, just enough to argue not convince). What is everyone else missing?
mclsound
159 posts
 
PMC are worth every dime"""USED $$""" but the MRSP is absolutely outrages.
timlub
2,039 posts
 
I have heard very good bass all types of inclosures, including Transmission Lines, as it has been alluded to here already, the line can be quite long and quite frankly, the transmission line enclosure is the toughest to get right. I believe that is the single reason that you don't see alot of transmission lines, but done right, they drive the speaker down...down quite well. This design allows us to get deep bass from smaller drivers.
It is also very difficult to get a great driver that will do very well in a sealed box, but when done correctly, I still prefer a sealed box bass with the proper finished qtc.
Again, "when done correctly" Good Listening, Tim
unsound
7,329 posts
 
It seems to me that though it might be possible to build a TL with the necessary dimensions, with or without "stuffing tricks", for most of us, it would be impractical to house, and even more difficult to market. Of course all designs necessitate compromise, and I suppose one could get some measure of the benefits of a TL in a more manageable package.
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