Transmission line speakers!

Khorn. A transmission line with a fold or two. Just my interpretation, as I am no speaker designer. PWK could have ported it, but would not get the efficiency of a true horn, nor the quality of output. Transmission loaded, ime, always had folds within the cabinets, otherwise, it was simply ported.

The K-Horn does have some folds, but is not functioning as a true 1/4 wave T-Line. It’s more like a wave guide or horn to help amplify certain ranges of the bass for efficiency gains, as opposed to absorbing resonance and allowing deeper bass from a given driver. Very different principles with different purpose and execution of the folds.

...as opposed to absorbing resonance and allowing deeper bass from a given driver. 

Bingo.

@roxy54  thanks, i lifted it from Wiki. i should have been more clear about that. Best to you !

Jim

My mains speakers are some transmission line IMF RSPM mark IV. 

I bought them in great condition from a junk shop a year or so ago.

My magnepan .7's and Dalhquist dqm9 have been pushed into a corner ever since. 

The IMF's are huge and heavy but are so easy on the ear. 

I am sure that design difficulty, cost of manufacture and shipping, and shear size are the reasons speaker like this became rarities.

I’m still using a pair of KEF Transmission Lines that my late father and I built in the mid ’70s.

They are made of 1’’ ply and are a CJ Rogers design with a KEF B139 bass, KEF B110 mid, KEF T27 tweeter and an ITT-STC 4001G Super tweeter.

They sound really nice with any amp but could probably do with a crossover rebuild. And a refinish as the original glued laminate hasn’t aged well and has been removed.

I have tried to include a picture but it won’t stick for some reason.