Carlspeak

This question is mostly for the AR historians and experts. Below is a dwg. of a tweeter. Based on my knowledge, the foam dots at the side of the dome coincide with the 3 mounting holes in their orientations. 

My question is, as manufactured, is the wire coming out of the left side of the dome (as one looks at the tweeter in the drawing) always the postitive wire?

The answer to my question is somewhat evident in fig. 3.6 of the AR3a restoration document, but not completely clear because fig. does not include the relationship between the + connection and the 3 mounting screws.  

TT? Roy? others?

Anybody have the part number? It doesn't show on the schematic in the LST manual.

If anyone has a spare they want to sell, PM me.

Are these interchangeable in the AR 90? I've run T/S tests on each and they measure differently. 200032 has about 1/2 the resonant freq. of 200028.

I recently did some close mic and far field on axis measurements on a vintage 19,XXX ser. speaker. The measurements were done with the drivers in situ in a 3a cabinet and xover functioning. The woofer was an Alnico version with cloth surround and #7 coil. With one exception, the the roll offs of the drivers were similar to those shown in the library copy of the 3a driver's separate responses http://www.classicsp...requency_resp/. However, it was noted the roll off of the midrange above 5000 hz (red curve in right pic below) was much shallower than shown in the library test. I would have thought the shallower roll off should have been higher in light of the series 50 uF (LP) capacitor and series #1 coil (HP).  
Note also the very good HF extension of the tweeter out to almost 20 kHz. I haven't seen this stellar a performance before in such a vintage (1968) 3a.
 
The second response test shows the 1 meter on axis system response. The measurement is gated @ ~300 hz and each vert. div. is 5 dB. Here we see a gradually declining 6 dB/octave response from 300 hz on up. Not surprising to me is the observation that my measurement looks similar to some of those done by Roy Allison in his co-authored study of numerous home installations of 3a speakers http://www.classicsp...d_in_home_lis/.  

I'm looking for a pair of cabinets for a new project. PM me with details and pricing.

 

Also willing to acquire detail drawings of the LST cabinets so I can get cabs made.