Offered for your consideration is one (1) CTS Alnico magnet 1½ inch dome tweeter that was original equipment in an Audio Dynamics’ ADC 303A speaker, USA-manufactured in 1967.  As you probably know, CTS was a major supplier to the domestic speaker industry from the late 1950’s through the 1970’s. Based on the EIA source/date code on the large magnet cover, “137 706”, this tweeter was made by CTS (137) in the 6th week of 1967.

I had never seen a CTS dome tweeter from the 1960's, so I believe this is fairly rare. I’ve owned ADC 303A’s made a few years later and they used CTS paper cone tweeters.  So, if you're buying it to replace a blown tweeter in your ADC 303A, be certain this is the version that you need.

Please see my large photos and read the remaining description to decide if this interesting CTS dome tweeter should be yours.

This CTS tweeter is in clean, very good condition. The clear poly dome with poly suspension ring is in great shape with no dents or dimples, just some errant factory assembly adhesive visible. Also, the upper faceplate had a bit of rust so I carefully unscrewed it from the frame, cleaned it, and then neatly applied a few spray coats of matte black enamel before re-attaching.

In addition, the anodized steel basket and magnet cover have only light oxidation and there’s some factory assembly glue visible. Plus, the magnet cover has aluminum dust shields which adds a nice touch. And, I’ve left a good, usable length of the factory +/- terminal input wires for the new owner’s convenience when splicing-in to their speaker. Overall, this early CTS dome tweeter is quite well preserved.

Most importantly, it’s been fully tested and sounds very clear and detailed with crisp highs rated to a sparkly 20kHz by ADC. Plus, I tested its DC resistance at 6.9Ω consistent with a nominal 8 ohm driver rating. And, the black faceplate measures 3½” in diameter, the galvanized steel flange is 4” diameter, and the whole assembly stands just over 1⅝” tall.

Lastly, there are no mount holes on this tweeter design—it is secured from the rear of the ADC 303A cabinet with steel retention clips. For anyone considering this tweeter for a speaker-building project, I still have those cabinet mount clips and will include them.

So, as pictured and described, this early CTS dome tweeter made for ADC is offered at a competitive price.

I encourage interested parties to ask any questions they may have about this listing before committing to purchase. Payment is due at checkout by PayPal or other accepted methods. U.S. mailing addresses will pay $9.95 for very carefully packed shipping via U.S. Postal Service, FedEx, or UPS with tracking and delivery confirmation. International purchases accepted only from those who are able to pay with PayPal including shipping by U.S. Postal Service First Class Parcel Air Mail.

Thanks for looking!