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So I found these kinda rare original owner transmission line speakers over in Washington last week. Sound very good. Small company out of Portland in the 70's that also had nice amps I guess. Became eventually Rockford Fosgate. The speaker was designed by lynn Olson of the Aerial speaker fame. Came with the original owners manual.






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Nice find! How do they sound?
My first surround sound processor was a Fosgate Audionics DSL Two. Very high end at the time.



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Your speakers seems to be in very nice condition.

IMF and TDL speakers do have cult like following due TL principle. Size is also relative issue as TL-50´s do no occupy more area than AR2 or AR3 on stands... and stands are not needed.

I do have friend who made TL sub woofers to be used with Martin Logan electrostatics. He used old Richard Allan drive units and full length line loading instead more usual 1/4 length line. I suppose there is not too much sound on end of the line. Back wave most likely get absorbed almost completely in the stuffing of the line. And these sub woofers are not small.

You may find this interesting too http://www.imf-electronics.com/Home

Best Regards


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They really do sound nice. They can go low when the material does and the imaging seems particularly good. They remond me of my small Epos speakes, but a larger variety. Smooth and detailed. I initially had them hooked up to my Tube gear and I liked the warmth but felt they could use a little more oomph. Seems like they have a stronger presentation with the Adcom 5500 powering them but not as warm of course. I will go back to the tubes and see if I am correct.

In the literature it says the goal of the design was to provide an exceedingly linear response curves commensurate with their philosophy of producing wide range, accurate systems.

Here is the response curve measure 40Hz to 16kHz


http://www.nutshellhifi.com/ Here is where teh designer Lynn Olson went and some interesting info on speaker design can be found. I am going to email him today to see if I get a response.

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