Mint condition pair of Acoustic Research AR-3st supertweeters. They are in perfect working condition and have no nicks or damage. For use with AR-1 and AR-2. General Product Description of the Acoustic Research AR-3st 1-inch Super Tweeter. The AR-3 st used the Acoustic Research AR-3. Was designed originally to add a super-tweeter to the AR-1 or AR-2a system. It included a beautiful, solid-walnut, lacquer-finished cabinet with the AR-2-type grill cloth material (it could be ordered with the AR-1 saran-type grill material as well) and the famous solid-brass AR logo plate attached to the bottom-left corner (horizontal view). The system could be used in either a horizontal or vertical position. The AR-3 st included the standard AR-3 7,500 Hz crossover network. The AR-3 st tweeter was a new phenolic-dome tweeter, AR Part No. ST-0375 , and it was the first dome tweeter ever used in a commercially available loudspeaker. The AR-3st tweeter is probably the most recognized tweeter ever designed. With nearly perfect impulse response and excellent off-axis response, it is still to this day considered to be among the best-performing tweeters ever put in a loudspeaker. This tweeter design was first used in the famous AR-3 loudspeaker, introduced in October, 1958, and put into production in January 1959. This hard-dome tweeter was designed for the AR-3 by Edgar Villchur, and it was considered to be among the finest high-frequency transducers ever designed, both from the standpoint of its nearly ideal on-and off-axis frequency response and low distortion and coloration. Many experts and engineers considered this tweeter to be the equal of any electrostatic driver from the standpoint of transient behavior and linear, smooth response. 1-inch aluminum voice coil (this tweeter uses a free-form voice coil with no bobbin). Voice coil suspended in polyurethane-foam suspension. Voice coil sealed with butyl-latex coating around gap. Voice coil lead-out wires are aluminum. Top plate is -inch machined steel. Magnetic structure is 3.3 lbs Alnico-5 and Armco Iron. Mounting flange is specific to AR loudspeakers. Frequency response is ±1½ dB 7.5-20kHz. Sensitivity is approximately 86 dB. Tweeter used in AR-3, AR-3t, AR-3st, AR-2a and early models of the AR-2ax prior to 1969. This AR-3 st belonged to Acoustic Researchs export organization, Delrama International, and this tweeter has never been used, other than to be tested at Acoustic Research. It is NOS (new-old stock), and it has been stored since 1960. This beautiful speaker is in nearly perfect, like-new condition, and is pretty much as it was when it left the AR factory at 24 Thorndike Street in Cambridge, Massachusetts in late 1959. The item “Acoustic Research AR3-ST Supertweeters Mint Condition Speakers” is in sale since Sunday, October 02, 2016. This item is in the category “Consumer Electronics\Vintage Electronics\Vintage Audio & Video\Vintage Speakers”. The seller is “moesizzle.md-6″ and is located in McLean, Virginia. This item can be shipped worldwide.