Well I owned a pair of TDC speakers in the early 70s that were purchased at Tech Hifi. Tech Hifi was a New England audio chain store at that time. I thought the TDC name brand was the stores own because they were significantly cheaper than other more recognizable names. I don't remember the model number or driver configuration but at the time they were great sounding speakers for a high school student. Wow, I can't believe I remember all that. Been at this hobby a long time. I'll have to follow thisthread to see if anyone else has similar recollections.