Need Help on TDC Speakers

I have in my possession two main speakers. They are quite large each speaker has two 10" woofers, two 4 1/2" mids, and two tweeters. The only label on them shows them to be manufactured in Massachusets and it states "TDC-20". In the research I've done I discovered they may be proto-type speakers from the late 70's or early 80's and they may have some link to the Tannoy company. Please help me identify and possible assign a value to them. Thank You.
I owned a pair of TDC speakers in the early 70s while still in high school. Don't remember the model number but I do remember they were purchased from Tech Hifi which was an audio retailer in New England at the time. Don't know if they are still in business or not. I believe the TDC line was produced exclusively for Tech Hifi but don't quote me on that. When I purchased (actually my father purchased) the speakers we auditioned JBL, Advent and BIC along with the TDC. The TDC was much less expensive so that's how we went. I thought they were great at the time but haven't seen or heard them in years.
I've seen questions about TDC here before so you might search the archives. Good luck.
I used to own a pair of TDC 1 speakers. Actually, I guess you could say it was my first entry level mid-end system and consisted of the TDC model ones, a Cambridge Audio receiver (probably no more than 10 Watts RMS into 8 Ohms; in college I tried to drive a dorm-mate's new Advent 1s and no cigar, the amp just couldn't deliver the current quickly crapped out when we pushed the volume!), along with Garrard turntable with a Shure MM cartridge, all the for the rather high system price (for a student anyway) of $199 for the whole kitten kaboodle; they included the lamp cord speaker wire too!

The TDCs were a two way, sealed (no port) enclosure and they were soft at the top end, in fact I had to run the treble at 3 O'clock just to begin to get them to tweet.

But I discovered many new bands on that system from 1973 to about 1979 when I upgraded and gave away that system to a friend.

Anyway they probably aren't worth much now but I would be curious to know what became of TDC, a local Boston area manufacturer that really tried to get locally into the nascent "high-end" market in the early 70's. Tech HiFi, a local dealer chain carried the entire TDC line. Whatever happened to Tech HiFi?

I doubt very much that TDC had anything to do with British manufacturer Tannoy.
TDC was a Tech Hi-Fi house brand manufactured by AAL in Chicago. AAL eventually became MTX.
I owned a pair of TDC speakers during the early 70s while in high school. They were purchased at Tech Hifi to replace my home made speakers. My father bought them for me after we listened to JBL, Advent, BIC and probably a few others. The TDC were made exclusively for Tech Hifi and were an inexpensive alterative to the previously mentioned brands. I enjoyed the heck out of them back then. Don't remember what happened to mine and wouldn't expect them to be worth a lot of $.
I still have a set and love them dearly. They are 350 watts a piece and had 2 10" subs, 2 6" mids, and 2 horns. I too purchased them from Tech-HiFi in the 80's.