Custom made Transmission Line Spkrs

Preamble: I had a pair of 3-way bass reflex speakers in 1980 that were capable of handling 100 watts RMS, with a sensitivity of 97 dB @ 1 watt @ 1 meter. These were very pleasing to here all frequencies with only 0.01 watts, yes 1/100th of a watt, and would disturb the neighbors @ 1 watt! Bass response went down and grabbed your feet. At full power (with a 80 watt amp) they would fill a very big dance hall (did that for my 1st wedding), wifey loved to dance.

I am designing my own Transmission Line (TL) speakers... a 3-way capable of handling 100 watts RMS... using a 12" woofer (with 28.5 Hz Fs, 91 dB sensitivity, frequency response 25 Hz to 4500 Hz) and a 5" mid range and a 2" tweeter (each with the same 91 dB sensitivity to match).

This will be Project #1, I am refurbishing and redesigning my son's Pioneer 3-way speaker cabinets... with some modifications I can change his bass reflex cabinets into TLs.

 Project #2 is the real goal, a 2-way TL capable of handling 100 watts RMS. I have the speakers set aside in storage already for Project #2... a 12" woofer (with 16 Hz Fs, 97 dB sensitivity, frequency response 16 Hz to 4500 Hz). After refining Project #1 and making sure the calculations work out, Project #2 cabinets will be made with 2+ inch thick walls (very heavy) and the 2 internal folded baffles required to make the TL, about 5 foot tall.

I have been gathering information, spreadsheets, and formulas for the designing of TLs for the past 10 years. The concept has been stored in my memory for 40 years. The 1st design I saw in the 1970s was using the KEF model B139 woofer, one that is now only available used if you can find it. My 12" woofer choice I believe to be as good.

When I am finished with Project 1 (soon, maybe by August) I will post pictures and results.
Testing with my 60 watt RMS per channel amp and the Proprius 26 watt RMS amps.

I have a clean copies of the vinyl I will be playing to test these as well as some choice CDs.
 Emerson, Lake, and Palmer, vinyl
Pink Floyd, "Dark Side of the Moon", vinyl

BAK wrote: Steppenwolf Earschplittenloudenboomer

Hi, I am a massive Transmission line fan, assuming it is done correctly, there have been relatively few commercial suppliers of any volume, including IMF, TDL and currently PMC (together with a few lower volume ones).  There are others including IPL & AOS in Germany and I think Accoustic Zen in US?

Richardl60 wrote: Finally if you like getting your hands dirty in the construction... Very best wishes with your project, Richard

Thank you Richard.
 I will be modifying my son's Pioneer cabinets for my 1st project... cutting 2 in off the bottom and adding 4 in.
Then placing the woofer @ 1/5 th of the folded TL line to be tuned to the woofer's resonant frequency (with taper, wool stuffing, bracing, and other factors included in the calculations).

My second project will be all hand made by me. I expect project 2 to be very heavy... around 100 pounds, 45.5 kg, or more. I may have to reinforce my floor! 

I can't wait to start... other priorities keep getting in the way!

I have been checking out a recent piece of test gear for measuring direct audio frequency sound output from my speakers.


more to come...


Edited by BAK - 19 Feb 2016 at 11:54am